Tom400CFI

225 is not overheating. Fans don't even turn on until ~228-230 or so. When you're digital display shows 225, the analog will appear to show ~260. The analog gauge is not really a gauge; it is a "cold-medium-hot" indicator. When the engine temp gets above ~220 or so, the needle just moves to the "HOT" position which is in the general vicinity of the warning/hash marks. The gauge is dumb. Don't worry about the gauge.

I told you earlier how to confirm if water is circulating or not. Do one of those tests. If water is circulating -if your radiator is hot, then the pump is moving water, and the T-stat is open.


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Tom Winton

Ok, what if my o2 sensors are bad? Would that possibly make the car overheat? I do get a flashing "SYS" error on the digital display. This is a 92 Corvette. What areas of the diagnostic port do I need to touch with a paper clip to get my codes?

Tom Winton

Ok, but if I leave the cap off too long, coolant starts overflowing! What am I doing wrong?

Tom400CFI

No, O2's wouldn't make it over heat. KISS and Focus. You were concerned the water pump and/or T-stat isn't working....figure that out first.

SYS isn't a check engine light -which is the light that would illuminate if you had a code related to engine issues. SYS is CCM related. Does it have an aftermarket radio? If so, that is the most likely reason for the SYS light. To pull engine trouble codes, you jump pins A and B.

Tom400CFI

You're not thinking about how the system works...then seeing if what is happening agrees with how things should work. You don't need to have the cap off, for too long to see if water is flowing in the tank. Start the car, look in the tank...is water flowing? Shut the car off. 30 seconds? Maybe?

Forget about the over flow tank; warm up the car (get it over 190*F on the digital display), place your hand on, or shoot the middle of the radiator core with a temp gun. What is the temp of the radiator core? If it's HOT, or close to your digital temp read out in the car, then your water pump is working and your T-stat is open. You can eliminate those concerns and move on. If I were you and I were concerned about water pump operation and/or T-stat operation, this would be my first test. Once warmed up, this test takes about 10 second, to perform. Maybe 15 seconds.


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Tom Winton

I will let the temp go up further today on the digital display, then. Is it unusual that the coolant wants to overflow from the surge tank?! How can I watch the thermostat open, and movement if it wants to overflow on me?

Tom Winton

Ok, I will try this today after work and get back to you. Thanks for the help.

Tom400CFI

You should have the cap on, for checking the temp of the radiator core, so it shouldn't be over flowing. Does it overflow w/the cap on?

Tom Winton

No, nothing came into the overflow with cap on.

antfarmer2

You do have the over flow filled to the proper level. Are both hoses close to the same temperature?

Gibbles

silly question, when it overheats does your overflow fill up?

I had the hose that goes from the radiator to the overflow start leaking air on me, hottest day of the summer I found out I had an issue.
I hit just shy of 300f before I got it cooled off... it was a fun day...

Tom Winton

Yes, filled up to the line that says cold, when engine is cool.

Tom400CFI

Check the temp of the radiator core, once the engine is up to ~190*F or higher.

antfarmer2

Pull that tube off by the cap and and blow in it see if it blows bubbles in the over flow.

Tom Winton

I have not had the overflow go crazy at all, yet. If I pulled up on the release of the radiator cap, then hot water went into the overflow... But when I drove the car, I got check gauges and the digital was at about 260. No smell and no steam, as if nothing was going into the overflow. Someone at work just loaned me a digital thermo laser temp sensor gun.

Tom Winton

Ok, just got a temp laser gun from friend at work...

Tom Winton

Really? I got "check gauges" light when digital hit 260!

antfarmer2

Get the pressure tester I am thinking you blew a head gasket. If so drain the coolant pull the plugs spin the engine get the water out and oil well. stop driving it before you do more damage.

Tom400CFI

Don't you think he should confirm the pump/stat is working first? He's expressed concern about the pump install and operation a few times...

antfarmer2

Yes but you have covered this very well and I told him 250 will do damage. The pressure gauge will tell. I could not even get him to grab the hoses to tell if the pump and stat are working. now he heated it to 260.