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Discussion Starter · #1 ·
Hello everyone

I have a 1985 that just got a new engine and a rebuilt 700R4, the problem I am having is the temp gauge reads normal until I put it in gear and try to go anywhear then it will rapidly rise to 260 degrees. This will happen within 1 min. of startup if I try to move the car. I don't think that the engine can get that hot that fast.
I removed all the air from the system and replaced the temp gauge sender, it still does it.

I am currrently deployed so I can't get to it now but i am trying to gather all the info I can so when I get home I can start driving it again.

Any info would be appreciated
 

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I am deployed as well in Bahrain. The only way i can see your motor getting that hot that quick is if the coolant passages are blocked in the head where the temp should be taken. I would first replace the temp sending unit on the driver side head. Then work from there. You can also buy an el cheap temp gauge, and stick the wire type sending unit into the top radiator hole and carefully attach the hose. (this is for trouble shooting only) and check the temps... should see about 200-210....

Also, does the fan switch on? Is it working....?


Where are you deployed? Let me know....i get around the gulf alot...
 

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Could be an inaccurate reading on the gauge. You may want to do a feel test to see if it's really getting that hot that fast. If so, could be a handful of things... stuck thermostat, improper timing, blocked coolant passage ways... those are a few things I can think of.
 

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A friend of mine had the same type of problem after having a new engine installed in his 85. He asked me to look at it and I found that the guy had plugged the O2 sensor wire into the coolant temp. guage wire, and the coolant temp. guage wire into the O2 sensor. They are both located in the same area and harness, and have the exact same connector. You will probably have to look from underneath, but they are located on the drivers side right near the O2 sensor. The wire that is supposed to plug into the O2 sensor is pink. And the one for the coolant guage is green. I'll bet that is what happened cause his was acting the same way. Your car will run better too because it will keep it from going into closed loop.
 

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A friend of mine had the same type of problem after having a new engine installed in his 85. He asked me to look at it and I found that the guy had plugged the O2 sensor wire into the coolant temp. guage wire, and the coolant temp. guage wire into the O2 sensor. They are both located in the same area and harness, and have the exact same connector. You will probably have to look from underneath, but they are located on the drivers side right near the O2 sensor. The wire that is supposed to plug into the O2 sensor is pink. And the one for the coolant guage is green. I'll bet that is what happened cause his was acting the same way. Your car will run better too because it will keep it from going into closed loop.

Wow, that would be a major PITA to troubleshoot!
 

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Discussion Starter · #6 ·
Thanks

Thanks for all the input

I have removed the Tstat for Diagnosis purposes only and I have replaced the temp sending unit in the left head and the problem is still there.
When I get back I will check the timing and the wires for the 02 and temp sender.
the engine has maybe 3 miles on it so I wouldn't think that the coolant passages are blocked.

87 shark I am in Afghanistan for the 4th time, you stay safe
 

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It might also be full of air. Burping it would be my first step. I recently changed the anti in mine. It was a royal PITA getting the air out and the anti in. Later! Frank
 

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Wow, that would be a major PITA to troubleshoot!
Actually it turned out to be easy to find, because the O2 sensor voltage was not varying. It was fixed on 800mv. I knew what color wire went to it, and when I checked the O2 sensor, I noticed it was the wrong color wire.
 

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Actually it turned out to be easy to find, because the O2 sensor voltage was not varying. It was fixed on 800mv. I knew what color wire went to it, and when I checked the O2 sensor, I noticed it was the wrong color wire.
Yeah I see, that makes sense. It'd be a pretty quick indicator given no voltage variation.
 

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Discussion Starter · #11 ·
thanks

driley Thanks for the info ,
I know what wires you are talking about and I am sure that is the problem, so thanks for the help you saved me several hours of diagnosing this problem.
 

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driley Thanks for the info ,
I know what wires you are talking about and I am sure that is the problem, so thanks for the help you saved me several hours of diagnosing this problem.
Don't mention it. Glad I could help. :thumbsup:
 

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I need help with my 1985 corvette After a little bit of time using my Corvette like 20 minutes it starts to overheat I’ve had it over boil on me three times I already tried replacing the digital fan and flushing the radiator over and over any tips on how I can get it to stop overheating and yes the fan kicks on both the fans kick on and it’s still overheats
 

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Even though you flushed the radiator there still could be crud in there where you might only be usiong 1/2 of the radiator. I'd check witgh a good radiator shop
 
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