Home » Public Forums » GMCnet » Engine High Temp
Engine High Temp [message #370215] |
Wed, 27 July 2022 20:53 |
Tom Katzenberger
Messages: 399 Registered: June 2019 Location: Kingsville, MD
Karma: 4
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Gentlemen,
I just road tested my GMC. It had sat for 30 years and had 8,000 original miles. The engine is running great, but hot. The analogue guage indicated 225 degrees and steady. Up hill and down, all the way to 60 MPH and coasting. The Digi panel reports High engine temp, alarm and red emer. light.
The coach has a new 195 degree thermostat, new water pump, re-cored radiator and all new lines and hoses. I spun the fan clutch and got less than 1/2 rotation. Dash temp guage indicates first 1/4.
Do you guys think this is a result of running in a 45 year old engine with low milage? Maybe surface friction from an old stored engine or perhaps something else?
Thanks in advance for any tips.
Take care,
Tom K
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D., Micro Level, Howell EBL-EFI Spark Control, Macerator, York Air Compressor, 6 Wheel Disc, Quadra Bag, Onan W/Bovee Ignition
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Re: Engine High Temp [message #370221 is a reply to message #370215] |
Thu, 28 July 2022 10:23 |
JohnL455
Messages: 4447 Registered: October 2006 Location: Woodstock, IL
Karma: 12
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1) New thermostat. New thermostats are often junk. I highly recommend the Flowkooler 195.
2) fan clutch test. Your “spin test” tells really nothing valuable other than not frozen or not 100% free wheeling
A) at cold start after sitting and high idle, you must hear FAN ROAR for at least 2 mins that then subsides. Overnight gravity puts the silicone fluid into the working chamber causing fan engagement roar. Cold, the valve is set to pump fluid into the non working chamber. Takes a couple mins as fluid cold. This test shows that there is sufficient fluid in the clutch. If no fan roar at cold start, replace clutch. If it passes go on to B.
B) this test is fairly involved with restricting air and timing results (see manual) but in simple terms you should hear fan roar at the temps you are getting. If not then the bimetalic spring may be caked with road grime and not rotating. I have sprayed with WD-40, waited then sprayed again to flush grime away successfully. Or the clutch could be getting poor heat signal from underfilled coolant or not fully opening stat. Of course a missing or missalligned shroud will dilute the heat signal with cold air and prevent clutch action. Lastly a bad cap return valve or porous hose to overflow can pump coolant out hot, then return air during cool down. This misleads you into thinking cooling system is full but it is not. Again giving poor heat signal to clutch.
After all that sitting, there is a very very good chance your distributor vacuum and mechanical advance is gummed up. Retarded timing will cause overheat for sure.
I’m assuming you have fresh 50/50 Ethylene glycol coolant as you did rad work.
John Lebetski
Woodstock, IL
77 Eleganza II
[Updated on: Thu, 28 July 2022 10:35] Report message to a moderator
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Re: Engine High Temp [message #370222 is a reply to message #370215] |
Thu, 28 July 2022 12:16 |
Tom Katzenberger
Messages: 399 Registered: June 2019 Location: Kingsville, MD
Karma: 4
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Senior Member |
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John and Matt,
I will follow both instructions and get back. I don't hear the clutch fan roar and I will shoot the thermostat with the digital thermometer. I do feel the same as both the analog and Digi panel are probably more accurate then the dash gauge.
Thanks guys.
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D., Micro Level, Howell EBL-EFI Spark Control, Macerator, York Air Compressor, 6 Wheel Disc, Quadra Bag, Onan W/Bovee Ignition
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Re: Engine High Temp [message #370228 is a reply to message #370215] |
Fri, 29 July 2022 15:03 |
Greg C.
Messages: 224 Registered: October 2019 Location: Knoxville, TN
Karma: 0
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I would second checking the mechanical advance mechanism. I drove my coach 1000 miles back from Texas in July 2020 when I purchased it. It ran warmish the whole way, with ambient 90's temps and not a lot of power. While working on it when I got it home I discovered the mechanical advance weights were worn with elongated holes, and the shaft was gummed up with oil deposits and not advancing at all. I worked some Kroil down the shaft while manually moving the advance shaft until it loosened up. It now seems to run better and cooler. Of course, a new radiator core and Flow Kooler t stat helps I'm sure.
Greg Crawford
KM4ZCR
Knoxville, TN
"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
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Re: Engine High Temp [message #370231 is a reply to message #370215] |
Fri, 29 July 2022 23:09 |
Tom Katzenberger
Messages: 399 Registered: June 2019 Location: Kingsville, MD
Karma: 4
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Senior Member |
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Guys,
I should mention that the engine has EFI with EBL. I did shoot the thermostat housing with the digital thermometer and the analog gauge and digi panel gages are accurate as Matt said.
I purchased a new fan clutch. I will install it this weekend as well as a 9 pound cap. If the new fan clutch does not correct the issue, I will at least have a spare.
Thank you guys for your help I will let you know how Thing's work out.
Have a wonderful weekend,
Tom K.
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D., Micro Level, Howell EBL-EFI Spark Control, Macerator, York Air Compressor, 6 Wheel Disc, Quadra Bag, Onan W/Bovee Ignition
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Re: Engine High Temp [message #370234 is a reply to message #370215] |
Sat, 30 July 2022 19:50 |
Tom Katzenberger
Messages: 399 Registered: June 2019 Location: Kingsville, MD
Karma: 4
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Senior Member |
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Bruce,
I have not brought the EBL up yet. I came out of the EBL with USB male adapter going into USB-C port on the tablet. I think I have to go into the tablet with A USB port instead of the USB C port. I will play with the EBL tomorrow to see if I can bring it up and I really appreciate the information on the additional data points that the EBL can give me. I'm going to replace the fan clutch. If that doesn't work, I will reinspect the whole system.. I'm hoping that the new re-cored radiator is functioning properly as everything else is new. I was also wondering if the new fiberglass fan shroud would cover the whole radiator and may help the system perform better. Also, if the fan clutch is defective I may split the fan shroud when I install the new clutch as it appears that the clutch are frequently a failure point.
Thanks again guys for all your help I will let you know how things worked out.
Take care,
Tom K.
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D., Micro Level, Howell EBL-EFI Spark Control, Macerator, York Air Compressor, 6 Wheel Disc, Quadra Bag, Onan W/Bovee Ignition
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Re: Engine High Temp [message #370235 is a reply to message #370234] |
Sun, 31 July 2022 01:42 |
Bill Van Vlack
Messages: 419 Registered: September 2015 Location: Guemes Island, Washington
Karma: 14
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The EBL should work fine with either type of USB port. Go into device manager on the PC and find out which port appears when you plug it in, then set the WUD software for that port. If the PC also has the standard USB port, then just use whichever one is less likely to be used for something else. You can always switch back if you need to.
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid November 2015.
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Re: Engine High Temp [message #370238 is a reply to message #370215] |
Sun, 31 July 2022 09:55 |
Tom Katzenberger
Messages: 399 Registered: June 2019 Location: Kingsville, MD
Karma: 4
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Senior Member |
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Bill,
Thank you. I will follow your instructions. Wish me luck as I am not that tech savvy.
Thanks again,
Tom K.
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D., Micro Level, Howell EBL-EFI Spark Control, Macerator, York Air Compressor, 6 Wheel Disc, Quadra Bag, Onan W/Bovee Ignition
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Re: Engine High Temp [message #370380 is a reply to message #370215] |
Wed, 17 August 2022 14:29 |
jhbridges
Messages: 8412 Registered: May 2011 Location: Braselton ga
Karma: -74
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Senior Member |
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Along with the above recommendations, I'd do a flush of the block. Drain off and save the nice new coolant, fill it with water and fast flush, run it, do it again,and see what the flushed water looks like. Keep flushing till it comes out clean. Flush backwards, hose into the thermostat housing and out the lower hose. It may of grown some scale inside sitting.
--johnny
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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