Home » Public Forums » GMCnet » Engine Temperature Too Hot? (Engine Water Temperature)
| Engine Temperature Too Hot? [message #196740] |
Tue, 29 January 2013 08:23  |
Clark76
Messages: 62
Registered: February 2010
Karma: -2
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Question: 208 degrees seems too hot to be running the engine. Since I am not used to seeing the temps with my new gauges what should normal?
NEW GAUGE READINGS: I recently installed new high quality analog gauges and matched senders to replace the “Idiot” OEM gauges on the dash – Engine Temp, Trans Temp, Voltage, Oil Pressure, Air Tank Pressure. I recently drove over 1,000 miles and noticed that my Engine Temp did not change from 208 degrees and the Transmission Temperature varied from 180 to 195 degrees (I was towing a Geo Tracker). On one long steep grade it did get up to 220 degrees and the fan clutch kicked in. On the downhill side it cooled back to 208 degrees. Drove mostly on flat land a few hills, the fan did kick in when going up a few long steep grades. Outside ambient temperature 40 to 70 degrees in January. Drove 10 hours one day with a 1 hour lunch stop, 1 gas fill-up stop and two short dog stops. This summer in a few months it will get to the 90-105 degree ambient temps.
BACKGROUND: 76 GMC 455 engine, Mobil 1 Oil (new oil and filter before trip), New Water Pump before trip, Green Radiator Fluid 50/50 (held level nicely in reservoir), original headers and fairly new exhaust system, new heavy duty fan clutch installed 6 months ago, rebuild transmission 1 year ago. New oil sending unit replaced the old sending unit. There is a supplemental small transmission radiator cooler in front of the A/C cooler which is in front of the Radiator Cooler (And yes, the transmission cooler is tied into the transmission cooler that is in the big OEM radiator so heat transfer takes place). There is a 9# radiator cap on the unit.
OTHER POSTS OF INTEREST:
I do not know what the thermostat is in the radiator, but I have seen the posts on using a Robet Shaw 330-195 balanced flow thermostat 195 degree or the 330-180 is preferred. I understand that the 9# cap raises the boiling temperature to 250 degrees with
Reference Temperature Sender: http://www.gmcmotorhome.info/engine.html
Engine Temp Discussion Threads on GMCnet: http://gmc.mybirdfeeder.net/GMCforum/index.php?rid=0&t=msg&th=17989
http://gmc.mybirdfeeder.net/GMCforum/index.php?rid=0&t=msg&th=22412
http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&goto=129002&rid=0
http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&rid=0&th=19404&goto=147642
http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&rid=0&th=22163&goto=173055
http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&rid=0&th=20462&goto=157344
http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&rid=0&th=20239&goto=155354
GMC Cooling Issues (Installing Air Flow Modifications with Mud Flap Material) http://minniebiz.com/gmcmotorhome/2011/05/20/gmc-engine-cooling-issues/
GMC Engine Cooling System: http://www.gmcmotorhomeinfo.com/radiator.html
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| Re: Engine Temperature Too Hot? [message #196742 is a reply to message #196740] |
Tue, 29 January 2013 08:46  |
gbarrow2
Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...
Karma: 3
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Do you have any reason to believe the temp is or is not correct? What was the reading with your OEM sender and guage before you changed it out?
Why not get an IR thermometer and verify the temp before you change anything. The new matched set sending unit and gauge could be inaccurate.
Or devise a way to test the set against a good thermometer in water on your stove.
Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach
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| Re: [GMCnet] Engine Temperature Too Hot? [message #196746 is a reply to message #196740] |
Tue, 29 January 2013 09:53 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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I wouldn't worry for one moment about those temperatures, given the details
and conditions you stated. You still have a good safety margin before the
9 psi radiator cap allows boiling and your cooling fan seems to be
operating just as it should.
Even your "new high quality analog gauges" probably are spec'd at 5%
accuracy. If you have a 195*F thermostat and it's controlling the MINIMUM
temperature to exactly that, you could still have an allowable gauge
reading of 185*F to 205*F.
And if the thermostat also had a 5% accuracy (doubtful), your maximum
normal temperature reading might be as high as 215*F (or as low as 176*F).
Just consider what you're seeing as normal and watch for significant
deviations from that -- that's all the OEM gauges were ever good for.
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
On Tue, Jan 29, 2013 at 9:23 AM, Southmayd wrote:
>
>
> Question: 208 degrees seems too hot to be running the engine. Since I
> am not used to seeing the temps with my new gauges what should normal?
>
> NEW GAUGE READINGS: I recently installed new high quality analog gauges
> and matched senders to replace the “Idiot” OEM gauges on the
> dash – Engine Temp, Trans Temp, Voltage, Oil Pressure, Air Tank
> Pressure. I recently drove over 1,000 miles and noticed that my Engine
> Temp did not change from 208 degrees and the Transmission Temperature
> varied from 180 to 195 degrees (I was towing a Geo Tracker). On one long
> steep grade it did get up to 220 degrees and the fan clutch kicked in. On
> the downhill side it cooled back to 208 degrees. Drove mostly on flat land
> a few hills, the fan did kick in when going up a few long steep grades.
> Outside ambient temperature 40 to 70 degrees in January. Drove 10 hours
> one day with a 1 hour lunch stop, 1 gas fill-up stop and two short dog
> stops. This summer in a few months it will get to the 90-105 degree
> ambient temps..
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Engine Temperature Too Hot? [message #196755 is a reply to message #196746] |
Tue, 29 January 2013 11:32 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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I've a question, since I haven't put my DigiPanel in yet. I note the temp sender has a probe in the coolant flow, while the thermocouple for the DigiPanel is under a bolt on the metal of the engine.. so, which will read higher? Or will they stabilize to the same?
--johnny
'76 23' transmode norris
'76 palm beach
From: Ken Henderson <hend4800@bellsouth.net>
To: gmclist <gmclist@temp.gmcnet.org>
Sent: Tuesday, January 29, 2013 10:53 AM
Subject: Re: [GMCnet] Engine Temperature Too Hot?
I wouldn't worry for one moment about those temperatures, given the details
and conditions you stated. You still have a good safety margin before the
9 psi radiator cap allows boiling and your cooling fan seems to be
operating just as it should.
Even your "new high quality analog gauges" probably are spec'd at 5%
accuracy. If you have a 195*F thermostat and it's controlling the MINIMUM
temperature to exactly that, you could still have an allowable gauge
reading of 185*F to 205*F.
And if the thermostat also had a 5% accuracy (doubtful), your maximum
normal temperature reading might be as high as 215*F (or as low as 176*F).
Just consider what you're seeing as normal and watch for significant
deviations from that -- that's all the OEM gauges were ever good for.
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
http://www.gmcwipersetc.com/
On Tue, Jan 29, 2013 at 9:23 AM, Southmayd wrote:
>
>
> Question: 208 degrees seems too hot to be running the engine. Since I
> am not used to seeing the temps with my new gauges what should normal?
>
> NEW GAUGE READINGS: I recently installed new high quality analog gauges
> and matched senders to replace the “Idiot” OEM gauges on the
> dash – Engine Temp, Trans Temp, Voltage, Oil Pressure, Air Tank
> Pressure. I recently drove over 1,000 miles and noticed that my Engine
> Temp did not change from 208 degrees and the Transmission Temperature
> varied from 180 to 195 degrees (I was towing a Geo Tracker). On one long
> steep grade it did get up to 220 degrees and the fan clutch kicked in. On
> the downhill side it cooled back to 208 degrees. Drove mostly on flat land
> a few hills, the fan did kick in when going up a few long steep grades.
> Outside ambient temperature 40 to 70 degrees in January. Drove 10 hours
> one day with a 1 hour lunch stop, 1 gas fill-up stop and two short dog
> stops. This summer in a few months it will get to the 90-105 degree
> ambient temps..
>
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Foolish Carriage, 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
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| Re: [GMCnet] Engine Temperature Too Hot? [message #196758 is a reply to message #196755] |
Tue, 29 January 2013 12:01 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Johnny,
Unless the design of the Digipanel includes an offset for its sensor's
non-submersed location, it will definitely read lower than the coolant
temperature. The question that I can't answer (nor can anyone else, IMHO)
is, "How much lower?" The conductivity of the iron and of the various
junctions between the H20 and the sensor, the temperatures of the coolant
and the ambient air, and perhaps other parameters, all come into play.
They will not stabilize to the same unless the ambient temperature
equalizes with the coolant temperature. So the only rational answer is, as
always, "Figure out normal and watch for deviations."
Ken H.
On Tue, Jan 29, 2013 at 12:32 PM, Johnny Bridges wrote:
> I've a question, since I haven't put my DigiPanel in yet. I note the temp
> sender has a probe in the coolant flow, while the thermocouple for the
> DigiPanel is under a bolt on the metal of the engine.. so, which will
> read higher? Or will they stabilize to the same?
>
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Engine Temperature Too Hot? [message #196759 is a reply to message #196746] |
Tue, 29 January 2013 12:25 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Since your temperature is steady except when pulling a heavy load up hill, I have to assume that you have one of two things going on.
1. The gauge is incorrect or,
2. The thermostat is opening late at a higher temperature.
So you need to determine if you have a measurement or an operational problem.
I subscribe to the Dick Paterson idea of a cooler,NOT COLD, engine (and trans) is a happy engine and trans. Because your trans temp also reads higher, I have to assume that both of your gauges are either correct or both are reading high. More than likely they are correct. The trans and it's fluid gets its heat from two main sources. The running engine it is bolted to, and the torque converter. Is some cases the trans fluid is also warmed by the trans cooler in the radiator as it's fluid is circulated by the warmer coolant in the radiator. So trans temperature is indirectly affected by engine temperature and more directly affected by the torque converter and trans internals.
I have an external oil cooler and an external transmission cooler. When driving on flat terrain my engine coolant temperature varies between 178 and 184 as the thermostat opens and closes. My trans temp normally stays below 150 so I do not really watch it much.
Based on all of this I suggest you change your thermostat. I prefer a 180 degree one in my GMC but if you insist you could install a 195. Keep in mind that the 180 or 195 number is the start to open point. The thermostat will not be fully open for a few more degrees. Also the thermostat opening and closing is NOT an instant thing. So there will be some small delay in opening and closing as the coolant temperature changes. If you want to watch this happen, take a thermostat and put it in a pan of water. Heat the water (and thermostat) on a stove with a thermometer in the water. I do this to any thermostat I am going to install in any vehicle just to make sure it is a good one.
I do not think your temperatures are disastrous but I like mine running cooler.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Engine Temperature Too Hot? [message #196772 is a reply to message #196755] |
Tue, 29 January 2013 15:35 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Johnny,
I have the H2O thermocouple for the DigiPanel under one of the thermostat housing bolts and the cheap Harbor Freight gauge tracks it
pretty damn close. Double Trouble has an aluminum radiator and at highway speeds on a 90F day the Harbor Freight reads 160F and
the DigiPanel reads as pictured in this link:
http://www.digi-panel.com/photo.htm
Regards,
Rob M.
Sydney, Australia
AUS '75Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: Johnny Bridges
I've a question, since I haven't put my DigiPanel in yet. I note the temp sender has a probe in the coolant flow, while the
thermocouple for the DigiPanel is under a bolt on the metal of the engine.. so, which will read higher? Or will they stabilize to
the same?
--johnny
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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
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| Re: [GMCnet] Engine Temperature Too Hot? [message #196777 is a reply to message #196772] |
Tue, 29 January 2013 16:25 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Johnny,
Damn!
I shouldn't respond to questions until AFTER I have my morning coffee!
Change the 90F to 60F.
I believe I have a 180F thermostat installed and the reason the temp runs below 180 is because the amount of water that flows
through the thermostat bypass is enough to cool the engine down.
Regards,
Rob M.
Sydney, Australia
AUS '75Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Robert Mueller
Sent: Wednesday, 30 January 2013 8:36 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Engine Temperature Too Hot?
Johnny,
I have the H2O thermocouple for the DigiPanel under one of the thermostat housing bolts and the cheap Harbor Freight gauge tracks it
pretty damn close. Double Trouble has an aluminum radiator and at highway speeds on a 90F day the Harbor Freight reads 160F and
the DigiPanel reads as pictured in this link:
http://www.digi-panel.com/photo.htm
Regards,
Rob M.
Sydney, Australia
AUS '75Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: Johnny Bridges
I've a question, since I haven't put my DigiPanel in yet. I note the temp sender has a probe in the coolant flow, while the
thermocouple for the DigiPanel is under a bolt on the metal of the engine.. so, which will read higher? Or will they stabilize to
the same?
--johnny
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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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
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| Re: [GMCnet] Engine Temperature Too Hot? [message #196821 is a reply to message #196758] |
Wed, 30 January 2013 06:26 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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Thanks, what I wantwed to know. "Gonna read a bit lower" is the gist of it. The reason I usually use an analog multimeter is to catch deviations and direction as opposed to deadnuts accuracy.
--johnny
'76 23' transmode norris
'76 palm beach
From: Ken Henderson <hend4800@bellsouth.net>
To: gmclist <gmclist@temp.gmcnet.org>
Sent: Tuesday, January 29, 2013 1:01 PM
Subject: Re: [GMCnet] Engine Temperature Too Hot?
Johnny,
Unless the design of the Digipanel includes an offset for its sensor's
non-submersed location, it will definitely read lower than the coolant
temperature. The question that I can't answer (nor can anyone else, IMHO)
is, "How much lower?" The conductivity of the iron and of the various
junctions between the H20 and the sensor, the temperatures of the coolant
and the ambient air, and perhaps other parameters, all come into play.
They will not stabilize to the same unless the ambient temperature
equalizes with the coolant temperature. So the only rational answer is, as
always, "Figure out normal and watch for deviations."
Ken H.
On Tue, Jan 29, 2013 at 12:32 PM, Johnny Bridges wrote:
> I've a question, since I haven't put my DigiPanel in yet. I note the temp
> sender has a probe in the coolant flow, while the thermocouple for the
> DigiPanel is under a bolt on the metal of the engine.. so, which will
> read higher? Or will they stabilize to the same?
>
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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Foolish Carriage, 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
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| Re: Engine Temperature Too Hot? [message #196839 is a reply to message #196740] |
Wed, 30 January 2013 09:20 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Did not quote what Clark76 wrote on Tue, 29 January 2013 09:23
Question: 208 degrees seems too hot to be running the engine. Since I am not used to seeing the temps with my new gauges what should normal?
Clark,
Even if you are actually running at the temperatures you are reporting, it will not harm the hardware.
As KenH said, the accuracy of automotive instruments leaves a lot to be desired. Even at the expected maximum error, you are still not in any trouble. It is worrisome - Yes, but not a big issue.
I will suggest that you do find out where the variation is. Automotive thermostats VERY rarely develop an offset high, but electric instruments can do it easily.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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