Over heating???

[Dogrider72]

Hello group, I have a 86 k10. Just put in rebuilt 350. Double hump heads, headers, rv cam. Holley street advanger 670.

My problem is when I start it and it runs at idle temps go up to 220-240. I know send unit is right. It has 180 therm, new water pump, new radiator.

When I drive it, temps drop to 210. Could the gauge be bad. When the 305 motor was in before, I couldn't get temp over 100. Need help

 

[Camar068]

found the link below googling. You can also pull the thermostat out and see if it still does it. As cheap as thermostats and sending units are, I'd gladly swap them out one at a time before I pulled the gauge cluster out.

http://www.americanautowire.com/view-faq/general-motors-temperature-gauge-troubleshooting/

 

[jetman]

If you have one of a infrared thermometer you can easily do a thermal trace on your cooling system. Harbor freight has a non-contact thermometer for ~ 12 bucks.

 

[dougbert]

get a good inexpensive temp gauge that you can use as a "test" gauge and hook it in. That would provide information on if it is in the engine or in the gauges.

also like the thermal gauge from HF idea

dougbert

 

[Georgeb]

Just a note. If you use Teflon tape on the sender it won't read correctly. I mentioned it because there has been work done and the difference between this engine and the original 305 is so big. Have you noticed the gauge reading differently or warmer than usual when the engine is cold?

Or you may have a sticky t-stat. I would suggest drilling a 1/8" hole through the plate of the t-stat to let accumulated air pass through and vent off too.

How are the heater hoses run? Should go out from the manifold to the heater core then back to either the radiator or the water pump port.

Just covering some bases here.

 

[1987 GMC Jimmy]

If you have one of a infrared thermometer you can easily do a thermal trace on your cooling system. Harbor freight has a non-contact thermometer for ~ 12 bucks.

Ooh, good price. Is that on the shelf usually, or do you have to order it?

 

[jetman]

Ooh, good price. Is that on the shelf usually, or do you have to order it?

Have 'em on the shelf at HF store in Houston, price will be less if you have a 20% coupon.

 

[87scotty]

I would look into fan clutch and have a peak through the radiator to make sure its not clogged if it drops down while driving seems like not enough airflow at idle just my .02

 

[87scotty]

And you have a shroud around fan correct?

 

[1987 GMC Jimmy]

Have 'em on the shelf at HF store in Houston, price will be less if you have a 20% coupon.

Went to the Metairie store tonight and got me one. I sure needed one, but I wish I would have known about the coupon. Thanks!

 

[Jarhead79]

Also make sure you don't have any air in the system, that can make your motor get hot with a trapped air bubble.

 

[Camar068]

hopefully he got it fixed.