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[GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329071] Mon, 12 February 2018 01:25 Go to next message
BobDunahugh is currently offline  BobDunahugh   United States
Messages: 1690
Registered: October 2010
Location: Cedar Rapids, IA
Karma: 12
Senior Member
You can calibrate them to meaningful numbers.

For the temp gauge. Drive the coach to reach it's normal operating temp on the stock gauge. Pull to the side of the road. Raise the engine lid. Point an infred temp sensor on the thermostat housing. ( These temp sensors are a must tool to own, and travel with. ) Then use a fine tip Sharpie to put a dot on the face of the temp gauge IF the temp reading looks right. Now you'll know normal, and the temp for your GMC while on the road. A side benefit of this is. That this reading just might tell you that you do have a cooling issue now. Most long term over heating issues are from radiator problems.

For oil pressure. This can all be done in the driveway. Remove the stock oil pressure sender. Located close to, and left of the thermostat housing. Install a mechanical oil pressure gauge were you removed the stock sending unit. Get to normal running temps. Then run engine up to 2,000 RPM's while in park. Make note of the mechanical gauge reading. Then idle engine. Note this idle pressure reading. Then put the stock oil pressure sender back in . Start engine. Put dots on your stock pressure gauge lens at the idle, and the 2000 RPM readings. Idle reading as low as 10 PSI are fine. For GM cars, and trucks that only had low pressure lights. GM had those lights come on at 7 PSI as a rule. Remember that GM felt that anything above 7 PSI at idle was adequate to protect their factory warranty. 22 PSI was felt as an acceptable driving low pressure. Again to protect their warranty.

If you do fined your oil pressure readings AT GM's low limits. A cheep, dirty way to put off an engine rebuild for awhile. ( This will NOT fix your worn out engine. ) Is to install a high volume oil pump. They're 50% longer then stock oil pump. Thus 50% more volume. They DO NOT put out more pressure. As both stock, and high volume pumps have relief valves in them that are generally set at around 35 PSI. The reason your oil pressure can be low comes from excess bearing clearance due to wear of the bearings, crank, and oil pump. The high volume pump simply puts out more oil to overtake the oil requirement of worn out bearings. The GM engineers over sized the original oil pump to start with to deal with future engine wear for the life of the engines.

If you really want to protect your engine. Get the Digi Panel from Jim K at Applied GMC that has the sound alarm if there's troubles under the bonnet. ( The bonnet term is meant to make Rob M happy ) GRIN. Bob Dunahugh 78 Royale
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Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329074 is a reply to message #329071] Mon, 12 February 2018 07:47 Go to previous messageGo to next message
Johnny Bridges is currently offline  Johnny Bridges   United States
Messages: 6402
Registered: May 2011
Location: Braselton ga
Karma: 34
Senior Member
Then 22PSI running is adequate for my coach? I feel much better if that's correct. It starts over 40PSI cold idle but drops drastically when it comes up to temp. This with 15-45 Rotella. It does, however hold 30 or so at a minimum. Tell me that's safe and I'll quit worrying over it.

--johnny


76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. "I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased
Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329076 is a reply to message #329074] Mon, 12 February 2018 08:02 Go to previous messageGo to next message
Kingsley Coach is currently offline  Kingsley Coach   United States
Messages: 2533
Registered: March 2009
Karma: 2
Senior Member
Johnny
You aren't the only one waiting for more info on this. I've been mentally
doing a rebuild for 6 months now..if I could put it off one more year......

Mike in NS


Virus-free.
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On Mon, Feb 12, 2018 at 9:47 AM, Johnny Bridges via Gmclist <
gmclist-AT-list-DOT-gmcnet-DOT-org> wrote:

> Then 22PSI running is adequate for my coach? I feel much better if that's
> correct. It starts over 40PSI cold idle but drops drastically when it
> comes up to temp. This with 15-45 Rotella. It does, however hold 30 or
> so at a minimum. Tell me that's safe and I'll quit worrying over it.
>
> --johnny
> --
> 76 26' Eleganza(?) with beaucoup mods and add - ons.
> Braselton, Ga.
> "I forgive them all, save those who hurt the dogs. They must answer to me
> in hell" - ol Andy, paraphrased
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>



--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS

Life is too short to hold a grudge; slash some tires and call it even !
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Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329079 is a reply to message #329076] Mon, 12 February 2018 09:43 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
Messages: 6562
Registered: March 2007
Location: S.E. Michigan
Karma: 33
Senior Member
Johnny Bridges wrote on Mon, 12 February 2018 08:47
Then 22PSI running is adequate for my coach? I feel much better if that's correct. It starts over 40PSI cold idle but drops drastically when it comes up to temp. This with 15-45 Rotella. It does, however hold 30 or so at a minimum. Tell me that's safe and I'll quit worrying over it.

--johnny

Kingsley Coach wrote on Mon, 12 February 2018 09:02
Johnny You aren't the only one waiting for more info on this. I've been mentally
doing a rebuild for 6 months now..if I could put it off one more year......

Mike in NS

Neither of you should worry.

Lube oil pressure is only required to get the lube oil where it needs to be and still have it do its jobs.
What are its Jobs?? (More or less in order of accepted importance)
Cooling, things like bottoms of piston crowns
Flushing, the debris from wear and combustion so it will not interfere
Damping, keeping metal parts from banging in each other
Working fluid, for things like lash adjusters and chain tensioners
Metal surface isolation, preventing metal parts from working on each other
Lubrication, forming the hydraulic wedge that actually is the bearing in rotating parts

Notice I got to six before hydraulic lubrication?
Does the pressure of lubricating oil as it is delivered to the bearing of a plain bearing system matter?
Not really, all the oil has to do is get there and the rotating journal will pull it into the load areas.

In an engine such as a BB Olds, you really only need enough lubricating oil pressure to deliver it to the lash adjuster (cam followers) for everything to be good. Everything else (we don't have a chain tensioner), can be handled by the lube oil that is thrown around by the crank. So, regardless of what the oil pressure gauge says, if the engine is not making nasty noises at road load, it is probably good and will be for some time to come.

All that said, low lube oil pressure at idle is an indicator of wear. But is it wear of the bearing, the lash adjusters and bores or the lubrication oil pump itself. There is just no way to know. The best one I have personally known was an engine that was shut down on low lube oil pressure and the problem was a seized valve. That seized valve cause the pushrod to couple and that took the load off the cam follower that popped out of the bore and so there went the lube oil pressure. We got a new pushrod, cleaned the valve stem and screwed the cylinder had back down and put it back in service for another few years.

Matt


Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329088 is a reply to message #329071] Mon, 12 February 2018 12:28 Go to previous messageGo to next message
Johnny Bridges is currently offline  Johnny Bridges   United States
Messages: 6402
Registered: May 2011
Location: Braselton ga
Karma: 34
Senior Member
Aweright, Matt. I feel better, I'll get more time out of it. It doesn't use oil to any amount, but drinks gas like there's no tomorrow. It has too much cam at idle but will spin the wheels on request. I hafta sort the injector this spring, therein may be the mileage problem. However if it lunches on the way to Bean Station, it's On you Smile

--johnny


76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. "I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased
Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329089 is a reply to message #329088] Mon, 12 February 2018 12:32 Go to previous messageGo to next message
James Hupy is currently offline  James Hupy   United States
Messages: 4680
Registered: May 2010
Karma: 34
Senior Member
Spinning wheels might have sumthin to do with drinking gas. Jus sayin.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

On Feb 12, 2018 10:29 AM, "Johnny Bridges via Gmclist" <
gmclist-AT-list-DOT-gmcnet-DOT-org> wrote:

> Aweright, Matt. I feel better, I'll get more time out of it. It doesn't
> use oil to any amount, but drinks gas like there's no tomorrow. It has too
> much cam at idle but will spin the wheels on request. I hafta sort the
> injector this spring, therein may be the mileage problem. However if it
> lunches on the way to Bean Station, it's On you :)
>
> --johnny
> --
> 76 26' Eleganza(?) with beaucoup mods and add - ons.
> Braselton, Ga.
> "I forgive them all, save those who hurt the dogs. They must answer to me
> in hell" - ol Andy, paraphrased
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329091 is a reply to message #329089] Mon, 12 February 2018 13:39 Go to previous messageGo to next message
Kingsley Coach is currently offline  Kingsley Coach   United States
Messages: 2533
Registered: March 2009
Karma: 2
Senior Member
Having read that, I think I'll put it off for two more years !

Mike in NS


Virus-free.
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On Mon, Feb 12, 2018 at 2:32 PM, James Hupy wrote:

> Spinning wheels might have sumthin to do with drinking gas. Jus sayin.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>
> On Feb 12, 2018 10:29 AM, "Johnny Bridges via Gmclist" gmclist-AT-list-DOT-gmcnet-DOT-org> wrote:
>
>> Aweright, Matt. I feel better, I'll get more time out of it. It doesn't
>> use oil to any amount, but drinks gas like there's no tomorrow. It has
> too
>> much cam at idle but will spin the wheels on request. I hafta sort the
>> injector this spring, therein may be the mileage problem. However if it
>> lunches on the way to Bean Station, it's On you :)
>>
>> --johnny
>> --
>> 76 26' Eleganza(?) with beaucoup mods and add - ons.
>> Braselton, Ga.
>> "I forgive them all, save those who hurt the dogs. They must answer to
> me
>> in hell" - ol Andy, paraphrased
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>



--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS

Life is too short to hold a grudge; slash some tires and call it even !
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Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329095 is a reply to message #329071] Tue, 13 February 2018 07:54 Go to previous messageGo to next message
Johnny Bridges is currently offline  Johnny Bridges   United States
Messages: 6402
Registered: May 2011
Location: Braselton ga
Karma: 34
Senior Member
Can't agree, Jim. Road speeds of 60 - 65 per on cruise. The spinning at startup if you aren't careful is due I believe to a lack of traction in front coupled with a breathed-on engine. To the degree that it wouldn't go up a slight grade on a wet gravel county road in MO. I had to fall back and get a running start. This with a no slip differential which simply means both front wheels spin when there's no traction.

--johnny


76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. "I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased
Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329100 is a reply to message #329095] Tue, 13 February 2018 08:52 Go to previous messageGo to next message
James Hupy is currently offline  James Hupy   United States
Messages: 4680
Registered: May 2010
Karma: 34
Senior Member
Johnny, 65 pushes a bunch of air in front of the coach. Something like "
inversely proportional to the square of the speed" or some other axiom.
When I was a teenager, my mother bought me a subscription to Mechanix
Illustrated. There was a monthly contributor called "Uncle Tom" McHale.
(sp) who did automobile tests. Once a year they did the Mobilgas Economy
Run, and he revealed all the secret tricks they used to improve fuel
economy. One was inflating the bias ply tires to 50 psi. Another was to
place a piece of wood under the accelerator. Swapping thermostats,
maximizing ignition timing, coasting with the engine off on downhills,
driving like you had a balloon under the foot feed was one of his
favorites. Anyway, he always drove under 50 bring the tests. Steady speed,
no jack rabbit starts. You get the picture. If you or I am following
someone who drives like that, it is sure to cause road rage. But it does
save gas.
Jim Hupy
Salem, Or

On Feb 13, 2018 5:55 AM, "Johnny Bridges via Gmclist" <
gmclist-AT-list-DOT-gmcnet-DOT-org> wrote:

> Can't agree, Jim. Road speeds of 60 - 65 per on cruise. The spinning at
> startup if you aren't careful is due I believe to a lack of traction in
> front coupled with a breathed-on engine. To the degree that it wouldn't
> go up a slight grade on a wet gravel county road in MO. I had to fall back
> and get a running start. This with a no slip differential which simply
> means both front wheels spin when there's no traction.
>
> --johnny
> --
> 76 26' Eleganza(?) with beaucoup mods and add - ons.
> Braselton, Ga.
> "I forgive them all, save those who hurt the dogs. They must answer to me
> in hell" - ol Andy, paraphrased
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
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Unsubscribe or Change List Options:
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Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329101 is a reply to message #329100] Tue, 13 February 2018 09:22 Go to previous messageGo to next message
Keith V is currently offline  Keith V   United States
Messages: 1963
Registered: March 2008
Location: Mounds View,MN
Karma: 5
Senior Member
> Something like "inversely proportional to the square of the speed"
Ha ha do we wish!

Wind resistance is the Coefficient of Drag(CD) times the frontal area (A) times the speed squared (v^2)

https://en.wikipedia.org/wiki/Drag_(physics)

Drag depends on the properties of the fluid and on the size, shape, and speed of the object. One way to express this is by means of the drag equation:

F D = 1 2 ρ v 2 C D A {\displaystyle F_{D}\,=\,{\tfrac {1}{2}}\,\rho \,v^{2}\,C_{D}\,A} [F_{D}\,=\,{\tfrac {1}{2}}\,\rho \,v^{2}\,C_{D}\,A]

where

F D {\displaystyle F_{D}} [F_{D}] is the drag force,
ρ {\displaystyle \rho } [\rho] is the density of the fluid,[11]
v {\displaystyle v} [v] is the speed of the object relative to the fluid,
A {\displaystyle A} [A] is the cross sectional area, and
C D {\displaystyle C_{D}} [C_{D}] is the drag coefficient – a dimensionless number.


since CD p and A are fixed all you can do is reduce v^2
________________________________
From: Gmclist on behalf of James Hupy
Sent: Tuesday, February 13, 2018 8:52 AM
To: gmclist-AT-list-DOT-gmcnet-DOT-org
Subject: Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers.

Johnny, 65 pushes a bunch of air in front of the coach. Something like "
inversely proportional to the square of the speed" or some other axiom.
When I was a teenager, my mother bought me a subscription to Mechanix
Illustrated. There was a monthly contributor called "Uncle Tom" McHale.
(sp) who did automobile tests. Once a year they did the Mobilgas Economy
Run, and he revealed all the secret tricks they used to improve fuel
economy. One was inflating the bias ply tires to 50 psi. Another was to
place a piece of wood under the accelerator. Swapping thermostats,
maximizing ignition timing, coasting with the engine off on downhills,
driving like you had a balloon under the foot feed was one of his
favorites. Anyway, he always drove under 50 bring the tests. Steady speed,
no jack rabbit starts. You get the picture. If you or I am following
someone who drives like that, it is sure to cause road rage. But it does
save gas.
Jim Hupy
Salem, Or

On Feb 13, 2018 5:55 AM, "Johnny Bridges via Gmclist" <
gmclist-AT-list-DOT-gmcnet-DOT-org> wrote:

> Can't agree, Jim. Road speeds of 60 - 65 per on cruise. The spinning at
> startup if you aren't careful is due I believe to a lack of traction in
> front coupled with a breathed-on engine. To the degree that it wouldn't
> go up a slight grade on a wet gravel county road in MO. I had to fall back
> and get a running start. This with a no slip differential which simply
> means both front wheels spin when there's no traction.
>
> --johnny
> --
> 76 26' Eleganza(?) with beaucoup mods and add - ons.
> Braselton, Ga.
> "I forgive them all, save those who hurt the dogs. They must answer to me
> in hell" - ol Andy, paraphrased
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
69 Vette
29 Dodge
Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329102 is a reply to message #329101] Tue, 13 February 2018 10:08 Go to previous messageGo to next message
Marsh Wilkes is currently offline  Marsh Wilkes   United States
Messages: 105
Registered: January 2004
Karma: 0
Senior Member
I grew up reading Tom McCahill, hell of a guy!

https://en.wikipedia.org/wiki/Tom_McCahill

https://en.wikipedia.org/wiki/Tom_McCahill

Don't know if these links are working, but you can copy and paste.

Marsh (rarely post) Wilkes




-----Original Message-----
From: Keith V
Sent: Tuesday, February 13, 2018 10:22 AM
To: James Hupy ; gmclist-AT-list-DOT-gmcnet-DOT-org
Subject: Re: [GMCnet] Stock gauges. How to calibrate. As you just don't
really know the real temp, or oil pressure numbers.

> Something like "inversely proportional to the square of the speed"
Ha ha do we wish!

Wind resistance is the Coefficient of Drag(CD) times the frontal area (A)
times the speed squared (v^2)

https://en.wikipedia.org/wiki/Drag_(physics)

Drag depends on the properties of the fluid and on the size, shape, and
speed of the object. One way to express this is by means of the drag
equation:

F D = 1 2 ρ v 2 C D A {\displaystyle F_{D}\,=\,{\tfrac {1}{2}}\,\rho
\,v^{2}\,C_{D}\,A} [F_{D}\,=\,{\tfrac {1}{2}}\,\rho \,v^{2}\,C_{D}\,A]

where

F D {\displaystyle F_{D}} [F_{D}] is the drag force,
ρ {\displaystyle \rho } [\rho] is the
density of the
fluid,[11]
v {\displaystyle v} [v] is the speed of the object relative to the fluid,
A {\displaystyle A} [A] is the cross sectional
area, and
C D {\displaystyle C_{D}} [C_{D}] is the drag
coefficient – a
dimensionless number.


since CD p and A are fixed all you can do is reduce v^2
________________________________
From: Gmclist on behalf of James Hupy

Sent: Tuesday, February 13, 2018 8:52 AM
To: gmclist-AT-list-DOT-gmcnet-DOT-org
Subject: Re: [GMCnet] Stock gauges. How to calibrate. As you just don't
really know the real temp, or oil pressure numbers.

Johnny, 65 pushes a bunch of air in front of the coach. Something like "
inversely proportional to the square of the speed" or some other axiom.
When I was a teenager, my mother bought me a subscription to Mechanix
Illustrated. There was a monthly contributor called "Uncle Tom" McHale.
(sp) who did automobile tests. Once a year they did the Mobilgas Economy
Run, and he revealed all the secret tricks they used to improve fuel
economy. One was inflating the bias ply tires to 50 psi. Another was to
place a piece of wood under the accelerator. Swapping thermostats,
maximizing ignition timing, coasting with the engine off on downhills,
driving like you had a balloon under the foot feed was one of his
favorites. Anyway, he always drove under 50 bring the tests. Steady speed,
no jack rabbit starts. You get the picture. If you or I am following
someone who drives like that, it is sure to cause road rage. But it does
save gas.
Jim Hupy
Salem, Or

On Feb 13, 2018 5:55 AM, "Johnny Bridges via Gmclist" <
gmclist-AT-list-DOT-gmcnet-DOT-org> wrote:

> Can't agree, Jim. Road speeds of 60 - 65 per on cruise. The spinning at
> startup if you aren't careful is due I believe to a lack of traction in
> front coupled with a breathed-on engine. To the degree that it wouldn't
> go up a slight grade on a wet gravel county road in MO. I had to fall
> back
> and get a running start. This with a no slip differential which simply
> means both front wheels spin when there's no traction.
>
> --johnny
> --
> 76 26' Eleganza(?) with beaucoup mods and add - ons.
> Braselton, Ga.
> "I forgive them all, save those who hurt the dogs. They must answer to me
> in hell" - ol Andy, paraphrased
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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[GMCnet] Sure got this way off topic. Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329105 is a reply to message #329071] Tue, 13 February 2018 11:21 Go to previous messageGo to next message
BobDunahugh is currently offline  BobDunahugh   United States
Messages: 1690
Registered: October 2010
Location: Cedar Rapids, IA
Karma: 12
Senior Member
I started this topic in hopes of helping lurkers, and those new to our GMC's. What it's change to is also important to those owns. But as it's posted. It's more likely to be missed. My thought. Bob Dunahugh


________________________________
From: Bob Dunahugh
Sent: Monday, February 12, 2018 1:25 AM
To: gmclist-AT-list-DOT-gmcnet-DOT-org
Subject: Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers.


You can calibrate them to meaningful numbers.

For the temp gauge. Drive the coach to reach it's normal operating temp on the stock gauge. Pull to the side of the road. Raise the engine lid. Point an infred temp sensor on the thermostat housing. ( These temp sensors are a must tool to own, and travel with. ) Then use a fine tip Sharpie to put a dot on the face of the temp gauge IF the temp reading looks right. Now you'll know normal, and the temp for your GMC while on the road. A side benefit of this is. That this reading just might tell you that you do have a cooling issue now. Most long term over heating issues are from radiator problems.

For oil pressure. This can all be done in the driveway. Remove the stock oil pressure sender. Located close to, and left of the thermostat housing. Install a mechanical oil pressure gauge were you removed the stock sending unit. Get to normal running temps. Then run engine up to 2,000 RPM's while in park. Make note of the mechanical gauge reading. Then idle engine. Note this idle pressure reading. Then put the stock oil pressure sender back in . Start engine. Put dots on your stock pressure gauge lens at the idle, and the 2000 RPM readings. Idle reading as low as 10 PSI are fine. For GM cars, and trucks that only had low pressure lights. GM had those lights come on at 7 PSI as a rule. Remember that GM felt that anything above 7 PSI at idle was adequate to protect their factory warranty. 22 PSI was felt as an acceptable driving low pressure. Again to protect their warranty.

If you do fined your oil pressure readings AT GM's low limits. A cheep, dirty way to put off an engine rebuild for awhile. ( This will NOT fix your worn out engine. ) Is to install a high volume oil pump. They're 50% longer then stock oil pump. Thus 50% more volume. They DO NOT put out more pressure. As both stock, and high volume pumps have relief valves in them that are generally set at around 35 PSI. The reason your oil pressure can be low comes from excess bearing clearance due to wear of the bearings, crank, and oil pump. The high volume pump simply puts out more oil to overtake the oil requirement of worn out bearings. The GM engineers over sized the original oil pump to start with to deal with future engine wear for the life of the engines.

If you really want to protect your engine. Get the Digi Panel from Jim K at Applied GMC that has the sound alarm if there's troubles under the bonnet. ( The bonnet term is meant to make Rob M happy ) GRIN. Bob Dunahugh 78 Royale
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Re: [GMCnet] Sure got this way off topic. Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329107 is a reply to message #329105] Tue, 13 February 2018 11:39 Go to previous messageGo to next message
James Hupy is currently offline  James Hupy   United States
Messages: 4680
Registered: May 2010
Karma: 34
Senior Member
Sorry Bob, I am probably the principal offender for getting us off topic.
Anytime you have instruments, you need calibration to be absolutely
precise. Automotive gages are notorious for being inaccurate. Too many
variables to count. But, the IR thermometer and marking pen trick is not
bad for a S.W.A.G. method. Personally, I look for readings outside what I
normally see while driving. Low oil pressure, high temperature, fluid Temps
out of ordinary ranges, etc. I have a tachometer, vacuum gage, transmission
temperature, final drive fluid temperature, oil pressure, water
temperature, speedometer, and charge indicator. Thats enough to distract me
more than I like. More gages, more stuff to worry about. I guess that is a
point in favor of alarms and flashing lights like the digipanel. Live in
ignorance until an alarm goes off and jars you back into reality. Just my
take on it. Some of you airplane jockeys out there won't agree.
Jim Hupy
Salem, Or

On Feb 13, 2018 9:22 AM, "Bob Dunahugh" wrote:

I started this topic in hopes of helping lurkers, and those new to our
GMC's. What it's change to is also important to those owns. But as it's
posted. It's more likely to be missed. My thought. Bob Dunahugh


________________________________
From: Bob Dunahugh
Sent: Monday, February 12, 2018 1:25 AM
To: gmclist-AT-list-DOT-gmcnet-DOT-org
Subject: Stock gauges. How to calibrate. As you just don't really know the
real temp, or oil pressure numbers.


You can calibrate them to meaningful numbers.

For the temp gauge. Drive the coach to reach it's normal operating
temp on the stock gauge. Pull to the side of the road. Raise the engine
lid. Point an infred temp sensor on the thermostat housing. ( These temp
sensors are a must tool to own, and travel with. ) Then use a fine tip
Sharpie to put a dot on the face of the temp gauge IF the temp reading
looks right. Now you'll know normal, and the temp for your GMC while on the
road. A side benefit of this is. That this reading just might tell you that
you do have a cooling issue now. Most long term over heating issues are
from radiator problems.

For oil pressure. This can all be done in the driveway. Remove the
stock oil pressure sender. Located close to, and left of the thermostat
housing. Install a mechanical oil pressure gauge were you removed the stock
sending unit. Get to normal running temps. Then run engine up to 2,000
RPM's while in park. Make note of the mechanical gauge reading. Then idle
engine. Note this idle pressure reading. Then put the stock oil pressure
sender back in . Start engine. Put dots on your stock pressure gauge lens
at the idle, and the 2000 RPM readings. Idle reading as low as 10 PSI are
fine. For GM cars, and trucks that only had low pressure lights. GM had
those lights come on at 7 PSI as a rule. Remember that GM felt that
anything above 7 PSI at idle was adequate to protect their factory
warranty. 22 PSI was felt as an acceptable driving low pressure. Again to
protect their warranty.

If you do fined your oil pressure readings AT GM's low limits. A cheep,
dirty way to put off an engine rebuild for awhile. ( This will NOT fix
your worn out engine. ) Is to install a high volume oil pump. They're 50%
longer then stock oil pump. Thus 50% more volume. They DO NOT put out more
pressure. As both stock, and high volume pumps have relief valves in them
that are generally set at around 35 PSI. The reason your oil pressure can
be low comes from excess bearing clearance due to wear of the bearings,
crank, and oil pump. The high volume pump simply puts out more oil to
overtake the oil requirement of worn out bearings. The GM engineers over
sized the original oil pump to start with to deal with future engine wear
for the life of the engines.

If you really want to protect your engine. Get the Digi Panel from Jim K
at Applied GMC that has the sound alarm if there's troubles under the
bonnet. ( The bonnet term is meant to make Rob M happy ) GRIN. Bob
Dunahugh 78 Royale
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Re: [GMCnet] Sure got this way off topic. Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329110 is a reply to message #329107] Tue, 13 February 2018 15:37 Go to previous messageGo to next message
Jim Galbavy is currently offline  Jim Galbavy   United States
Messages: 1380
Registered: August 2007
Karma: 5
Senior Member
JimH, I'm like you. Too many gauges and I'm not watching the road. I use the same
gauges as you looking for changes from my norm. Plus I listen to the coach, feel for
changes in the ride and watch out for changes of smells. After 15 years, you know when
something has changed before the lights and gauges yell at you. Wink

jim Galbavy
'73 x-CL ANNIE
lake Mary, FL
Re: [GMCnet] Sure got this way off topic. Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329121 is a reply to message #329110] Wed, 14 February 2018 05:00 Go to previous messageGo to next message
SpookyEng is currently offline  SpookyEng   United States
Messages: 143
Registered: June 2016
Location: Navarre, FL
Karma: 1
Senior Member
Years of monitoring Aircraft Flight Engineer panels has made scanning guages second nature. Once you have confidence that your cruise indications are in the normal range (Bob's idea to verify gauge accuracy is a good one) you just have to notice the deltas fast enough to avert damage. If you have the stock guages the digi panel is a great way to let the coach tell you a parameter is out off limits. It also helps if your significant other drives, and is maybe less diligent about guage monitoring. That said, I prefer a full set of quality gauges so I can monitor exactly what is going on.

JD Lisenby- USAF Ret 1978 Royale-455 Electromotive Tec2 FI & ignition Navarre, FL
Re: [GMCnet] Sure got this way off topic. Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329122 is a reply to message #329121] Wed, 14 February 2018 05:18 Go to previous messageGo to next message
USAussie is currently offline  USAussie   United States
Messages: 15587
Registered: July 2007
Location: Sydney, Australia
Karma: 42
Senior Member
G'day,

I'm a big fan of the Digi-Panel:

http://www.appliedgmc.com/level.itml/icOid/451

Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808



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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426
Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329126 is a reply to message #329071] Wed, 14 February 2018 08:12 Go to previous messageGo to next message
Johnny Bridges is currently offline  Johnny Bridges   United States
Messages: 6402
Registered: May 2011
Location: Braselton ga
Karma: 34
Senior Member
Absolute precision in engine istruments is substantially less of a concern than change. When you mark the gauge, you're not nearly as interested in the absolute - though you can measure it for peace of mind - as you are in change. i.e. if the needle is off the dot, >why< is it off the dot. I've a nice set of digital gauges I'll likely put in the Ratrod if I ever make an instrument panel. They give absolute readings very well, but they're basically useless to see change unless you scan them long enough to digest the number and ask is it bigger, littler, or the same. That borders on the useless for the coach. Take Bob's approach. And as many of us do, ad the DigiPanel. It will get your attention if you're freeway fixated and something changes.

And if you want to see what the electrics are doing, put an ammeter - or two - in the coach. So it says 13.9 volts at highway speed. Cool. Is that 13.9 the float voltage of a charged chassis battery drawing maybe 4 -5 Amps at float, or a battery with a dead cell drawing 40 Amps? You'll find out when next you try to start the coach. Better to know ahead of time.

--johnny


76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. "I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased

[Updated on: Wed, 14 February 2018 08:14]

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Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329127 is a reply to message #329126] Wed, 14 February 2018 08:43 Go to previous messageGo to next message
Bullitthead is currently offline  Bullitthead   United States
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Registered: November 2013
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Senior Member
10-4 on the ammeter, Johnny...most people don't realize the value of that particular instrument, but you explained it well with few words.

Terry Kelpien ASE Master Technician 73 Glacier 260 Smithfield, Va.
Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329140 is a reply to message #329127] Wed, 14 February 2018 11:26 Go to previous messageGo to next message
emerystora is currently offline  emerystora   United States
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Registered: January 2004
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Senior Member
However, I don’t know if he meant a volltmeter or an ammeter. He said he wanted to read 13.39 volts and that would take a voltmeter.

Emery Stora

> On Feb 14, 2018, at 7:43 AM, Terry wrote:
>
> 10-4 on the ammeter, Johnny...most people don't realize the value of that particular instrument, but you explained it well with few words.
> --
> Terry Kelpien
>
> ASE Master Technician
>
> 73 Glacier 260
>
> Smithfield, Va.
>
>
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Re: [GMCnet] Stock gauges. How to calibrate. As you just don't really know the real temp, or oil pressure numbers. [message #329164 is a reply to message #329071] Thu, 15 February 2018 08:39 Go to previous messageGo to previous message
Johnny Bridges is currently offline  Johnny Bridges   United States
Messages: 6402
Registered: May 2011
Location: Braselton ga
Karma: 34
Senior Member
well, you can hardly resolve one decimal, much less two with an analog meter. Which begs the question, where in the GMC do you need this resolution?

--johnny


76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. "I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased
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