Help with temp guage? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Gramps69 · 08-21-2009, 11:21 PM

I have a '69 GMC 1500 LWB with a 292 L6. It has less than 20k miles on the motor. My problem is that the temp guage shows it is overheating when in slow traffic or at an idle. When I check the radiator, it is not bubbling hot or overflowing. In slow traffic, if I rev the motor to about 1500 rpm, it seems to cool off. Any suggestions? Thanks for your help.

retodd7711 · 08-22-2009, 01:37 AM

Quote:

Originally Posted by Gramps69

Any suggestions?

1. Check you radiator for damage. Bent fins lessen cooling ability.
2. Change your thermostat. A sticking thermostat could raise temp.
3. Check your water pump. Wear could be causing low water flow at low idle.
4. Flush your radiator inside and out. Dirt in the cooling fins can cause trouble.
That's where I'd start, keep us posted.

jwmdnm · 08-22-2009, 02:40 AM

I agree with all previously mentioned but make one additional suggestion.

Add a water temperature gauge. Hide it if you don't want to spoil the originality of the truck but I wouldn't trust the temp lights. They don't call them "idiot lights" for nothing.

I hope this helps

mclairmo · 08-22-2009, 08:33 PM

Sounds like a lack of coolant flow to me. Make sure you have the correct water pump and crank pulleys. The water pump pulley should be smaller than the crank pulley to keep the coolant flow up. Also, make sure to use a high flow T-Stat. Also, make sure water pump is in good shape. Try a bottle of Water Wetter from Autozone, too. If that does not work, then maybe you have a low rpm airflow problem. Try a full factory fan shroud (not the finger guard) and make sure fan is half way in and half way out of the shroud.

08-21-2009, 11:21 PM	#1
Gramps69 Registered User Join Date: Oct 2003 Location: Exeter CA Posts: 1	Help with temp guage? I have a '69 GMC 1500 LWB with a 292 L6. It has less than 20k miles on the motor. My problem is that the temp guage shows it is overheating when in slow traffic or at an idle. When I check the radiator, it is not bubbling hot or overflowing. In slow traffic, if I rev the motor to about 1500 rpm, it seems to cool off. Any suggestions? Thanks for your help. Last edited by Gramps69; 08-21-2009 at 11:39 PM.

08-22-2009, 02:40 AM	#3
jwmdnm Registered User Join Date: Nov 2008 Location: Robbinsville, NC Posts: 38	Re: Help with temp guage? I agree with all previously mentioned but make one additional suggestion. Add a water temperature gauge. Hide it if you don't want to spoil the originality of the truck but I wouldn't trust the temp lights. They don't call them "idiot lights" for nothing. I hope this helps __________________ '67 Chevy Stepside Shortie 350 GM crate motor with original 3-spd tranny

08-22-2009, 08:33 PM	#4
mclairmo Registered User Join Date: Jan 2006 Location: Take Off Posts: 1,908	Re: Help with temp guage? Sounds like a lack of coolant flow to me. Make sure you have the correct water pump and crank pulleys. The water pump pulley should be smaller than the crank pulley to keep the coolant flow up. Also, make sure to use a high flow T-Stat. Also, make sure water pump is in good shape. Try a bottle of Water Wetter from Autozone, too. If that does not work, then maybe you have a low rpm airflow problem. Try a full factory fan shroud (not the finger guard) and make sure fan is half way in and half way out of the shroud.



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