We did pressure test it and it appears to be working as it should.
What was yours doing?

 

Some of us - including myself - have had the CTS side of the ECM go on the fritz. Mine for example was toggling between 230 and 250 at start up or shortly thereafter (and this just appeared out of the blue one day). Plugging in another CTS on a cold motor did nothing to change that. That's why starting with a cold read helps. You want to verify an ambient readout from the CTS and Air Temp Sensors and then watch the CTS rise to the thermostat, which when it opens, should cause the temp to drop back down a couple of degrees. It should then rise to fan temp. I'd be curious as to what yours is doing if only because you've got this wide variance between the Display and the CTS signal. A 12 to 15 degree difference between the intake mounted CTS and the right head gage sender just seems a bit odd.

 

I was seeing a steady increase in temp up to the 230s when I'm normally between 175-185. My cap was old, replaced it and everything was fine. I didn't do a pressure test, just changed it because it was cheap.

Good luck on finding the problem, overheating problems are a pain!

 

10 before TDC??? As opposed to 6??????

I can see how that will make it run hotter, but I can see NO WAY that will make it run cooler.

 

I set it at 6 today when I tried it.
I have another ECM to try tomorrow.

 

That makes NO sense. The radiator cap allows for the pressurization of the cooling system which only raises the boiling point. A defective cap, which would not sustain pressure, or as much, would allow the water to boil at a lower temperature (212° at sea level, unpressurized). Once boiling, the water temp won't go any higher.

A weak cap may have been responsible for the coolant coming to a boil at that temp, but it wasn't the cause of the coolant reaching that temp.

RACE ON!!!

 

Well, before I changed it, the coolant level had become low through boiling. I guess the radiator cap not holding pressure caused this, thus leading to higher temps. Sorry for kind of jumping over that in my previous post.

Higher temps came from not enough coolant. Not enough coolant came from defective radiator cap.

 

I'm no cooling expert, but something does not add up:

160 degree @ radiator inlet. 130 degree @ radiator outlet. Engine pushing 245 degrees. Thermostat changed a few times with no change. Head gaskets installed properly. Intake manifold gaskets (lokely) instaled properly.

Sounds like you have no flow or bad flow. How's the water pump? Are you sure it is flowing? Is the belt run properly to turn the impeller properly?

 

EXACTLY!!!

RACE ON!!!

 

I discounted the inlet and outlet temps as being artificially low, maybe because they were being measured through a rubber hose? If I understand correctly, the only thing between normal temps and running hot, is a few days and a head gasket change. With all due respect, the finger points to a problem with the head gasket job.

RACE ON!!!

 

Not to rock the boat but when you had the heads off did yo uhave them checked for cracks? Reverse rotation water pump?

sure the others are right, just something to think about (hopefuilly theres no next time around for you)

 

They matched 'Up-Up.' Is there a 'DS-PS?' I wonder how closely they matched hole patterns and sizes? Would not be the first 1,000th people to get a 'general fit' head gasket issue, either.

 

The belt routing has been checked and rechecked, it is correct.

It is a flow or a transfer problem or a indicator problem.

We changed the water pump from a NAPA unit that seemed to be ok to a Edelbrock Victor unit that according to the package was for my year model Corvette.

You are correct that things are not adding up.

There are several things that I can think of that can cause this problem.

The biggest thing I am having a problem with is reconciling the information I am getting.

The big difference in the readings of the temp sender in the head and the temp sensor near the front of the motor while running.

If I turn it off at a gauge reading of lets say 240 and a CTS reading of 220 and let it sit for ten minutes the two readings will be very close to each other.

Common sense tells me that it is really getting to hot and that the root cause of this is a lack of flow.

I think that because the temps of the radiator inputs and outputs are so low that it has to be a flow issue due to a wrong part or a incorrect assembly, with the chance of a bad part being very low on the list.


I am going to post more on this tomorrow, but for now I am tired, PUI, and am going to try to figure something out in the am.

I want to thank each and every one of you for you help and insight into this problem I am having.

As I have said before, I am going to figure this out.

thanks guys.

Greg

 

Yes, they were vacuum tested, cleaned and surfaced on a mill, not a belt.
I may have lost a head gasket today from it running hot but yesterday the CO2 (chem test/block test) came out fine.

 

No respect due if I screwed this up and that is sure what it is looking like at this point.

It would be such a rookie mistake.

The inlet and outlet temps were on the AL on the radiator itself, from side to side at the top of the radiator.

At this point it looks like we made a mistake at some point.


I am going to sleep on it and decide what to do tomorrow.

 

you guys covered pretty much everything. i don't really think it's your radiator itself but it is one thing you have not checked and they do fill up with junk over time which drastically reduces how they cool. one easy test to check if the radiator is even able to cool is to get the car up to that 240ish degree temp and spray the radiator under the car with a garden hose. if your temps drop like a sinker; you have just indentified the problem.

 

The fact that 170' IN is so much less than what the guage is showin' doesn't bother me - I think that's cause there's supposed to be some drop there, and maybe cause you're readin' the hose, not the coolant.

I still don't get that one. The earlier the fuel fires, the the more it's still gonna' be gettin' squeezed before it gets to downstroke. MORE HEAT???

Ask him to explain that...

 

With the engine fully warmed up and idling and the radiator cap removed, do you see any bubbles in the coolant? Any smoke out of the exhaust?

Borrow a pressure tester from AutoZone to check your gasket seal quality; head and intake.

Jake

 

Timing that's too far retarded will cause the engine to run hot and will even cause the exhaust headers to glow a bright, pretty red. This is because the air/fuel mixture is still burning as it enters the exhaust. Burning should be completed before the exhaust valve opens.

At night, turn the garage lights off; makes a really pretty color.

Jake

 

We pulled them out and cleaned them, the radiator is not plugged, inside or out.