Overheating

Tiny
TROUBLE1980
  • MEMBER
  • 1985 CHEVROLET CAMARO
  • 5.0L
  • V8
  • RWD
  • AUTOMATIC
  • 149,000 MILES
Hello, my car has a 350 sbc with rebuilt 700r4 transmission, new water pump, alternator, battery and radiator. I am having overheating problems any time I drive over fifty five mph car runs 190/210 all day long driving city streets, but as soon as I drive over fifty five mph temperature rises to 230+ within a couple miles at that speed. Radiator blows all fluid out the cap all under the hood and into the overflow. Please help with any suggestions. Oh, by the way, no white smoke coming out of the tail pipe and no milky oil, but I do think it could be thicker the oil that is. I also have sudden bursts of smoke coming through my fire wall into my cab of the car as well.
Friday, August 25th, 2017 AT 1:33 PM

7 Replies

Tiny
STEVE W.
  • MECHANIC
  • 15,241 POSTS
That sounds like a bad thermostat that is jot opening fully. When the engine starts to speed up and work harder the water moves faster due to the increasing rpm's, If the thermostat does not open fully it becomes a restriction.
You changed the radiator so it should be okay, the other item would be if the hoses are collapsing and restricting the flow (which is the reason why some hoses have the stiff spring inside them) as the pump increases the flow.
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Friday, August 25th, 2017 AT 10:07 PM
Tiny
TROUBLE1980
  • MEMBER
  • 49 POSTS
Thank you Steve W. I appreciate your help I will go buy a new thermostat and hoses and see if that helps my problem. Also, if a car runs hot would a 160 thermostat be better than a 185?
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Saturday, August 26th, 2017 AT 3:48 AM
Tiny
STEVE W.
  • MECHANIC
  • 15,241 POSTS
I would stick with the factory temperature as your running in the right range (190-210) now. The overall operating temperature is determined by the amount of coolant and how large the radiator is.
The only time a lower temperature unit helps is on the race track where you can run a much larger radiator than you can on a street car and you do not really worry about mpg or the extra wear the engine sees.
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Saturday, August 26th, 2017 AT 9:41 AM
Tiny
TROUBLE1980
  • MEMBER
  • 49 POSTS
Steve the reason I asked is because I have a 160 in it because a 185 made the car jump to 230 plus at idle and and a 195 was worse. Is there an underlined problem other than the thermostat or hoses if that happens? Also, noticed my oil is smoking out of my valve covers today. What could be causing that?
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Saturday, August 26th, 2017 AT 3:14 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,241 POSTS
You have a more serious issue than just a thermostat if it is getting that hot that fast. This is an 85 with a 350 in place of the stock 305 correct?
Which parts did you use off which engines? I ask because it's possible you have the wrong water pump. GM used two different pumps for a few years 1985 was one of them. If the car came with conventional V belts it had a standard rotation pump. If it had a serpentine belt the impeller turned the other way because it drives off the back of the belt. The fan rotates the opposite direction as well. Both of those would cause the engine to run hot.

The other items that will cause a hot engine are advanced ignition timing, high compression, lean fuel mix, plugged/restricted exhaust or a blown head gasket.
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Saturday, August 26th, 2017 AT 6:27 PM
Tiny
TROUBLE1980
  • MEMBER
  • 49 POSTS
Steve, I am not sure about 1/2 of your questions. I just bought the car about three months ago and was told it was a new SBC 350 crate motor which I found was a lie. The water pump from a 1976 or 1978 impala bought at Autozone it does have a v-belt I know that because it just broke and when I bought one I had to get a corvette v-belt which was smaller than the one originally on it. And yes one side of my exhaust is blowing out hotter air than the other. I just went and checked that.
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Saturday, August 26th, 2017 AT 6:50 PM
Tiny
STEVE W.
  • MECHANIC
  • 15,241 POSTS
Okay, try to run down what the engine really is. You can find online charts for the casting numbers and see what you really have. Partly plugged exhaust will hold a lot of heat in the engine.
Also run a compression test and a cooling system pressure test the first will show if the engine has higher compression, the later to see if everything is sealed.

https://www.2carpros.com/articles/how-to-test-engine-compression
https://www.2carpros.com/articles/radiator-pressure-test
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Sunday, August 27th, 2017 AT 10:28 AM

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