cooling system problem

HULKZ28 · 04-07-2012, 08:40:16 PM

Im cruiseing down the highway today and lay into it a little. I look over at the temp gauge and its at 240..Usually runs 180..After just a few seconds it falls rapidly back to 190..I got off the hway a couple miles later and its back up again..I pulled off to let it cool and check the coolant..It blew some coolant off into the catch''beer'' can, and wet down the engine compartment a bit..After I added the coolant I made it back home with no issues,about 12 miles..Does this sound like a sticking T-stat? I wondered if the stock radiator is suffecient for 430 or so hp also..The water pump seems to be working as I can see a strong flow of coolant in the rad..Any thoughts..
Thanks.

455 Formula · 04-07-2012, 10:05:26 PM

I went through 3 thermostats in my 413 Pontiac (same size thermostat as your Chevrolet) that did the exact same thing. The first was a Stant, and then two MotoRads.

When I took the thermostat out, and ran only the hollowed-out thermostat body, the car runs 145° all the time and less than 170° on the dyno under load.

The only reason I put a thermostat in the car was to make my wife comfortable when she was driving it.

Made more power on the dyno too running the motor cold....Robert

HULKZ28 · 04-09-2012, 06:26:05 PM

Thanks for the reply. I think ill look for a colder t stat...195 is what the stock one is..You think there is a power increase with a colder engine??I read an article once that nascars run hot because they make more power at a higher temp..I thouight it was around 230 that they ran at.Could be due to their specs??

TheMeat · 04-09-2012, 09:32:53 PM

Try a 180* stat. A 195* one in my car had similar issues to what you write about but not quite that high in temps. I replaced it with a 180* unit and it is pretty rock steady.

REARSPROCKET · 04-10-2012, 07:25:19 AM

The Robert Shaw type that Mr. Gasket sells as HP balanced like this one work excellent. Also I run 180* in the fall and 160* during the heat of summer.
http://www.summitracing.com/parts/MRG-4364/

Andelin74 · 04-10-2012, 03:38:22 PM

Mine does the same thing sometimes, check for leaks near the top of your cooling system and follow your temp gauge line to see if its hitting a header or something. I have a feeling its air bubbles.

COPO · 04-10-2012, 04:22:43 PM

Too cold will give you less HP. I've had the same stat in mine for the last 27 yrs with no issues.

BondoSpecial · 04-10-2012, 05:05:00 PM

Regardless of running the car way cold giving more or less power, I would just be worried about too cold not cooking out moisture over time. If you never reach boiling, where is the moisture inherent to operating in IC engine going?

Damon · 04-10-2012, 08:16:15 PM

Anything 160* or above is plenty warm to keep the engine healthy and happy. I, too, have found that colder stats often make a smidge more power.

The REAL reason I run a colder stat is because at the dragstrip engine heat builds FAST during the run. The stat lags behind in it's opening and things can get a bit toasty on the big end if you're pulling out of the burnout box already at 190*.

Start the run at 190, finish at 210. Start at 160, finish at 180. Give or take- rough rule of thumb I use.

GOLF72 · 04-10-2012, 09:42:16 PM

Sounds like an air buble in the system. I converted my Porsche 914 to a Chevy 350 and your symptoms are classic to what mine used to.

If you burp the system it should be an easy fix (assuming it is not your t-stat).

To burp the sytems simply start your car with rad cap off. You should see the water flowing and it will bubble up (burping). Once that happens and it is flowing with no more burps, put the cap on and get the car to operating temp. The water should flow some to the overflow tank. Let it sit for a while to cool. Fill it up with water, or anti freeze and road test her.

HULKZ28 · 04-14-2012, 08:09:29 AM

I took the t stat out and snipped off the whole center section..Just a restrictor now..It takes a while to warm up and runs at 155 after a few miles..seems to run a little better..Hard to tell, could just be the day..always seems different day to day.. Thanks
Golf72, I have 2 944s for sale if you know anyone looking..I see your on the left coast though..Ill post em in the classified section.

REARSPROCKET · 04-15-2012, 07:54:00 AM

Hulk the 160* will run at 170* in summer heat and 160* in the cool fall, also the 180* does the same 190* in the summer and 180* in fall or spring. You don't want it to run too cool or the oil wont reach proper temp. I wouldn't run under 170* that's why I run a 160* in summer and a 180* in the spring and fall.