Home » Public Forums » GMCnet » S & J Oil Temp (Low Oil Pressure When Warm)
| S & J Oil Temp [message #366091] |
Thu, 12 August 2021 17:52  |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Senior Member |
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When I put in my S&J, I bypassed the radiator lube oil cooler and used an external 16 pass Drerale cooler.
My problem is poopy oil pressure when the engine get warm. 21 lbs at 2400 RPMs. If I go into a hill, I can visibly see the pressure drop to 17. When I crest a hill, and start down it will go to 25 lbs. When the pressure is under 25, the engine has a "tick" at 2300-2600 that can't be good. It has been doing this for 1000+ miles, so it doesn't seem to be tearing things apart, but is troublesome at 2 AM.
I have run 3 other 455 engines and always had 37 lbs when pulling. I have no intention of pulling this engine to see why it has poopy oil pressure. Is there resistance in the radiator oil cooler?
I am putting in a "boat engine" external liquid-cooled oil cooler before the Derale. How do I plumb it for the coolest "heater hose" water. I know the lower radiator hose is coolest, but under suction from the water pump. The "heater hose" connection on the water pump is also a low pressure point.
If I steal water at the lower hose, I have a feeling it will stagnate between the two low points.
After the water heater? That seems like pretty hot water. One of you fluid dynamics types must have some ideas.
Thanks in advance
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| [GMCnet] Re: S & J Oil Temp [message #366092 is a reply to message #366091] |
Thu, 12 August 2021 18:33  |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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George,
Going up hills the engine does get warmer so the pressure will drop.You
might examin the filter mounting bracket and see if the valve there is
sealing properly.
On Thu, Aug 12, 2021 at 3:52 PM George Beckman
wrote:
> When I put in my S&J, I bypassed the radiator lube oil cooler and used an
> external 16 pass Drerale cooler.
>
> My problem is poopy oil pressure when the engine get warm. 21 lbs at 2400
> RPMs. If I go into a hill, I can visibly see the pressure drop to 17. When I
> crest a hill, and start down it will go to 25 lbs. When the pressure is
> under 25, the engine has a "tick" at 2300-2600 that can't be good. It has
> been
> doing this for 1000+ miles, so it doesn't seem to be tearing things apart,
> but is troublesome at 2 AM.
>
> I have run 3 other 455 engines and always had 37 lbs when pulling. I have
> no intention of pulling this engine to see why it has poopy oil pressure. Is
> there resistance in the radiator oil cooler?
>
> I am putting in a "boat engine" external liquid-cooled oil cooler before
> the Derale. How do I plumb it for the coolest "heater hose" water. I know
> the
> lower radiator hose is coolest, but under suction from the water pump. The
> "heater hose" connection on the water pump is also a low pressure point.
>
> If I steal water at the lower hose, I have a feeling it will stagnate
> between the two low points.
>
> After the water heater? That seems like pretty hot water. One of you fluid
> dynamics types must have some ideas.
>
> Thanks in advance
> --
> '74 Eleganza, SE, Howell + EBL
> Best Wishes,
> George
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| [GMCnet] Re: S & J Oil Temp [message #366093 is a reply to message #366091] |
Thu, 12 August 2021 18:35 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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A number of factors influence pressure. The size of the tubing is a big
one, number of restrictions in a tubing system is another. So, if you used
larger oil lines, routed them with gentle curves, used a less restrictive
oil cooler, you could reduce the pressure in a system.
On the other hand, if engine bearing clearances are too large, or an
oil pump has an early relief spring, etc. you could have low oil pressure
as well. Probably prudent to see which it is.
I have installed more than 10 S & J engines in GMC's, and have yet to
encounter low oil pressure like you are describing in any of them. Those
values you are describing would send me looking for another very reliable
pressure gage, and verify that I had enough viscosity in my oil supply.
Just where I would start. Verify the complaint. Is that pressure
really that low? Or, is that just what your gage is telling you?
Jim Hupy
Salem, Oregon
On Thu, Aug 12, 2021, 3:52 PM George Beckman wrote:
> When I put in my S&J, I bypassed the radiator lube oil cooler and used an
> external 16 pass Drerale cooler.
>
> My problem is poopy oil pressure when the engine get warm. 21 lbs at 2400
> RPMs. If I go into a hill, I can visibly see the pressure drop to 17. When I
> crest a hill, and start down it will go to 25 lbs. When the pressure is
> under 25, the engine has a "tick" at 2300-2600 that can't be good. It has
> been
> doing this for 1000+ miles, so it doesn't seem to be tearing things apart,
> but is troublesome at 2 AM.
>
> I have run 3 other 455 engines and always had 37 lbs when pulling. I have
> no intention of pulling this engine to see why it has poopy oil pressure. Is
> there resistance in the radiator oil cooler?
>
> I am putting in a "boat engine" external liquid-cooled oil cooler before
> the Derale. How do I plumb it for the coolest "heater hose" water. I know
> the
> lower radiator hose is coolest, but under suction from the water pump. The
> "heater hose" connection on the water pump is also a low pressure point.
>
> If I steal water at the lower hose, I have a feeling it will stagnate
> between the two low points.
>
> After the water heater? That seems like pretty hot water. One of you fluid
> dynamics types must have some ideas.
>
> Thanks in advance
> --
> '74 Eleganza, SE, Howell + EBL
> Best Wishes,
> George
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
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| Re: S & J Oil Temp [message #366094 is a reply to message #366091] |
Thu, 12 August 2021 19:07 |
6cuda6
Messages: 975
Registered: June 2019
Karma: -6
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Senior Member |
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What are you running for oil? As Jim said, have you put a real gauge on it?
Ive been told over the years that 10psi for every 1000rpm is ok (doesnt mean i like it or agree).
As far as were to connect a liquid cooled oil cooler, my thoughts are your just displacing the heat from the oil back into the motor really.... i think personnaly i would look into an external reservoir or have a bigger sump pan made for more oil capacity if changing oil viscousity didnt help.
Rich Mondor,
Brockville, ON
77 Hughes 2600
[Updated on: Thu, 12 August 2021 19:10] Report message to a moderator |
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| Re: [GMCnet] Re: S & J Oil Temp [message #366095 is a reply to message #366093] |
Thu, 12 August 2021 19:20 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Senior Member |
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James Hupy wrote on Thu, 12 August 2021 16:35
Just where I would start. Verify the complaint. Is that pressure
really that low? Or, is that just what your gage is telling you?
Jim Hupy
Salem, Oregon
Thanks, Jim. The gauge reads around 42 at cold start-up idle. it goes higher at any RPM. In 5-8 miles, the pressure begins to drop.
I am using Quaker Full Synthetic 10-30. I have a couple of bottles of my standby Delo 15-40 and will change as soon as my Blackstone kit arrives.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: [GMCnet] Re: S & J Oil Temp [message #366096 is a reply to message #366092] |
Thu, 12 August 2021 19:22 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Senior Member |
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jimk wrote on Thu, 12 August 2021 16:33George,
Going up hills the engine does get warmer so the pressure will drop.You
might examin the filter mounting bracket and see if the valve there is
sealing properly.
--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
Thanks, Jim.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: S & J Oil Temp [message #366134 is a reply to message #366091] |
Sat, 14 August 2021 13:39 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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I would remove filter and adaptor nut and cooler adaptor and secure the cooler adaptor out of the way. Screw same filter back on and add more same 10w-30 as needed. Drive same route. This will tell you if your cooler rig is restrictive.
John Lebetski
Woodstock, IL
77 Eleganza II
[Updated on: Sat, 14 August 2021 13:41] Report message to a moderator |
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