Your problem is cooling capacity. $.02

You need 1. a bigger or better radiator
2. an auxiliary pusher fan

I know that you checked timing and Air/Fuel. But check it again at idle and low rpms. I was told that nothing will cool a lean engine but more gas.

 

[QUOTE=Ironcross]See, it was easier than you thought and by merely removing that 160 stat. for a hotter one. QUOTE]

So how do we know for sure that going to a 180 fixed the problem? Maybe he just had a bad stat.

So I'm not convinced going from a 160 to a 180 fixed his problem. And I'm not trying to take sides on this issue...but I am curious to find out which theory is correct.

 

My thought is that he had a bad thermostat which would not open all of the way. If he is having cooling problems sitting still then I agree with some others that he is either not getting enough air flow sitting still(i.e. fan, fan shroud),his radiator is not up to the task for this new engine, or both, but if his temps are good now then I still think bad thermostat...
I don't believe that a 160 to 180 mattered. Just my opinion.

 

I Think that the thermostats issue is a dead end and here’s why. There are two basic types of thermostats; those that fail open and those that fail closed. If the thermostat has failed closed then it would not matter how fast the engine is running the car is going to overheat and will overheat faster at higher RPMs. If the thermostat fails open then car more than likely will not over heat because the coolant is flowing freely through the engine and radiator. And lastly, if the thermostat is opening slowly, then the temperature will rise in the engine until the thermostat opens at which point the temperature of the coolant and engine will drop as the coolant begins to flow.

That leaves two things if the Air/Fuel ratio and timing are OK.

Radiator and water pump.

I think that you can take away the water pump because he does have a problem at high speeds, which means that it is flowing enough coolant at higher engine speeds. This could be the problem at lower speeds or idle. This is easily checked by removing the radiator cap to see if the coolant is flowing at idle.

What is left is the airflow through the radiator. If all of the seals are in place and the clutch fan has been removed then,………
You need a bigger cooling surface (radiator) or more airflow through the existing cooling surface.

I could be dead wrong.

But I had the same problem last summer. An after 2 thermostats and one water pump, tuning hours, I replace the radiator and the problem went away.

 

The best way to test the radiator is to have someone with an temperature gun scan the fins of the rad and look for cool spots (bad). It can look like it has flow and still not be up to snuff.

 

Lets start with your first scenairo!
Take the thermostat completely out and see what happens, want to bet it wont boil?

Air fuel ratio!
Where did that come from? I was under the impression this was about cooling.

Bigger radiator!
I guess GM dont know how to build a car. It didn`t overheat from the factory.

Oh, and by the way, unless you havn`t noticed the person with the problem in the first place feels comfortable with the mere switching to a 180 thermostat has solved his problem.

 

Period.

 

I told you I could be dead wrong.

As far as the Air/Fuel goes, I was refering to an engine running very lean.

And the person with the problem doen't have a stock car from the factory

But I still trying to understand why changing from a 160 to 180 would have an effect on cooling in traffic or at Idle. Can someone educate me. Or can we assume that it was a bad thermostat.

 

Newbie Answer:
The only way a thermostat can make your car run hot is if it is not opening properly. If you remove it water/coolant does not stay in engine long enough to heat up and your engine does need to get to a certain temperature to operate properly. I had a Ford Ranger once upon a time (I know, I know) and when the thermostat got stuck in it, I pulled it to get home. It would not get hot enough to run right (computer controlled fuel injection) until I replaced it. If you remove it, you need to gut it and put it back in to create a restriction to allow the engine to reach a decent operating temp.

That is what I know about thermostats, one that is too cool cannot make an engine overheat....

 

On first thinking, it might seem logical that slowing the flow of coolant through the radiator will make it "cool better" but in this situation it just ain't true.

I think our friend has seen a false result - putting the higher temp stat in has remedied the problem, most likely because the old, lower temp one was not opening properly, or was in some way more restrictive.

You pump the coolant through the rad slower, and it may have "more time" to cool down before coming back into the engine, but then the coolant in the engine will have "more time" to pick up combustion heat.

The heat transfer out of the radiator scales proportionally with the flow rate through it and the temp diff across it. So, say the air flow is relatively constant, then the more coolant you're pumping through the rad, the more heat you're rejecting from the engine.

 

Come on just for fun go get a new OEM 160 and put that in and prove this theory. The other stat was just bad !!!!!!!!!!!!1

 

Well he said it fixed his problem, but he also said he installed new rad hoses at the same time. His lower hose could have been collapsing. Since he did thermostat and hoses at the same time we will never know.

Greg