Help with overheating issues

My 89 used to be like that. In the end I ran no thermostat during the summer with dual electric fans. I had many people tell me that the Trick Flow stage one cam with the big duration and lift was causing it to run hot like that, but with no tstat it ran fine 99% of the time

Running without no stat is bad news.

Cylinder wear increases dramatically with coolant temps below 180F. Not to mention efficiency and power losses. If the cooling system is really that bad, there is something seriously wrong. Professional race teams would not even consider going without a stat.

The only other thing I can think of right now is how the rad is mounted. If you put the rad in lower than it was originally then the overflow is no longer the high spot in the system. The high spot (which may now be in the back of the intake), will collect steam pockets which will block coolant flow. This did happen to me when I swapped to the 351w block.
Hope this helps
Good luck

You could start by deacreasing your coolant mix. I know of no additive that's able to absorb and transfer heat better than plain ole water. That alone should be worth a few degrees. It's just not necessary to run 50/50 this time of year. You need only enough coolant to change the boiling properties of the water so that it doesn't turn to steam and vaprize so quickly. 25 or 30% is more than enough in the summer months. I tend to lean more towards the lower concentrations of coolant then add what I need in the winter to bring it to -20 freezing point.

I wouldnt run the stock tstat anyway. You have a nice setup, but then you throw in a 195* stat. Keep in mind that if your engine is rising in temp and it gets to 195 and then the fan kicks on and tries to cool it... its gonna have a hard time. I would have done a 180* stat and a bottle of Redline Water Wetter!

edit: like andy said, Antifreeze actully HOLDS heat, so lowering your mix would intern lead to a cooler temp.

Water transfers heat 2.6 times more efficiently than E/G coolant.

I knew someone would scoff at the no stat comment, but, lower operating temperatures lead to less wear in the long run. Running without the tstat during the summer only makes it run "cold" for a few minutes. Mine would run between (depending on day, temp, and traffic) 160 and 190 without the stat. Now ponder this; if you run cooler than average all the time, and the oil doesn't get as hot as it usually does, then the oil doesn't break down like it normally would and the lubricity (I know lubricity isn't a word, but it works) factor stays higher causing less wear and tear on internals, less buildup in the pan, and cooler engine bay temps for cooler air intake temps. Now, how can you dispute all those benefactory points?

raininfire said:

Well car seemed to run fine yesterday, i burped it before I left work and took an hour drive and it stayed at about 200 the entire trip. And also stayed at 205-200 today going to work. Not sure if I burped it right, but I started the car with the cap off, waited for the t-stat to open and run for a bit squeezed the hose, a bunch of air came out it seemed. Capped it back up. Is that right? I am going to try the 180 tstat soon. But being my daily driver and I work 7 days a week its a bit hard to even get to that.

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Sounds like just an air pocket. Very cool. Also when you burp the cooling system be sure to have the heater on so that coolant flows through the heater core well. If the coolant temps stay the way they are I personally would stay with the stock stat. I am using a 180 now just because the motor is fresh and will tend to run a little hot anyway. As soon as the temps come down a little I will put the stocker back in and switch to syn. oils.

Many will disagree with this, but I am convinced that the stock stat is best for engine longevity, power, efficiency, and emissions. Yes I do care about emissions, whether I get tested or not.

The Seattle GreenLake hippies are rubbing off on me. Well, at least they quite rubbing me.

stang99x said:

I knew someone would scoff at the no stat comment, but, lower operating temperatures lead to less wear in the long run. Running without the tstat during the summer only makes it run "cold" for a few minutes. Mine would run between (depending on day, temp, and traffic) 160 and 190 without the stat. Now ponder this; if you run cooler than average all the time, and the oil doesn't get as hot as it usually does, then the oil doesn't break down like it normally would and the lubricity (I know lubricity isn't a word, but it works) factor stays higher causing less wear and tear on internals, less buildup in the pan, and cooler engine bay temps for cooler air intake temps. Now, how can you dispute all those benefactory points?

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More is not always better. Or less when discussing heat. First remember that hp is created by heat that makes the air in the combustion chamber expand. When the air has expanded, it forces the piston down on its power stroke. The more heat that is put into the air, the more power you will make. If the coolant is constantly taking away more heat than is necessarry, you will never make your hp potential. The coolant is meant to prevent damage to components at excessive temps (over 230 or so), and preventing detonation. If it does more than this efficiency (and thus power) is hurt.

For oil temps, ideal is between 200-230F. You should not consider your engine oil "warmed up" until 160F. That means no hard driving until 160F. You will not lose power until the oil reaches 240F. Oil will not break down until 265F. All of these numbers came from Four Stroke Performance Tuning by A. Graham Bell.

While I cannot find the source right now I do remember seeing a table in the last couple of days that showed the steep rise in cyl wear as engine temps dropped. This means that running at 160F will dramatically decrease the life of your piston ring to bore seal. You will start to lose compression and thus power. Running at 180 would be better, 195 best (arguably).

Actually lubricity is a word (although benefactory is not ).

Cooler intake air temps will produce more power, to a point. The problem is that anything in the combustion chamber must be heated before it will combust. This is the same concept as having to heat all the ice in a pan to melt it to water, before any of the water will boil. Using heat to bring things up to combustion temps is going to hurt your power and efficiency. Extremely cool temps will also weaken the atomization of fuel, which leads to incomplete combustion.

What I would recommend for your set up is to run a 180 stat and check your oil and coolant temps. If you really are having problems (based upon the temps listed above), make sure the coolant system is in good shape (flushed and a good mix). Try running syn. oil. This alone can lower oil temps, but is most likely not absolutely necessarry for a mild street car.

Your thinking is not that far off, you just need to keep in mind that when dealing with any automotive modification there will be a compromise.

I see where you are coming from. Although I sold the car last year, I am still interested in what may have fixed it as I have future plans to build another one every badder than the first one.

I ran synthetic oil, I tried adjusting the % of coolant to water both ways, higher and lower (just to set a precedent for myself) I tried all the goofy specialized hoses, high flow WP, I used the 180* stat in the winter. I couldn't for the life of me get that car to run cool in the summer without removing that stat. I have a be cool radiator I picked up at FFW commerce, the WP was an edlebrock, good year blue silicon hoses, you name it I had it.

And, just wondering, I am having a wiring issue with an 86GT. Know anything about that?

After taking several classes and reading a couple of books on automotive electrical/electronic components and systems I have come to the conclusion that electricity is magic. I don't understand it. But post your problem because there are several e- experts on this site.

After reading over what you had tried the only other thing I can think of is that maybe a head gasket was installed incorrectly. This could have blocked off coolant flow? Tough to say though.

I hope your next car goes better than the last!