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Dear all members,

Today I got my car back with a used engine installed. My previous engine had a main bearing problem and was knocking severely, as many people might remember. After I started the car in the garage the engine was a little bit hot running at 112 centigrade at idle and the mechanic told me to drive the car a little bit and see if it overheats and bring it back in that case. The mechanic had done the pressure test and it was ok. After driving the car for a while I noticed that the temperature was 106 centigrade at low RPM and 112 centigrade at idle. I got a check engine light and cleared all the codes and it was ok. After driving the car for a little while more I revved it to 4500 RPM and the check engine light came back. The car almost immediately started to overheat badly and went up to 125 centigrade. I got the "engine coolant hot message" and the temperature light also came on. Shortly after the engine started smoking badly and steam was coming from under the hood. The car then cut power and it was like you were driving in neutral. I parked the car right away and opened the hood seeing that coolant was all over the engine.

I then borrowed a hose from a near by house and filled it with water. It was 6 liters low. I then slowly drove back to the mechanic at below 2000RPM and the car never over heated. I'm waiting for their response. The mechanic is saying that the engine that I bought from a salvage yard might have a cracked block. The codes that I get are PO 36 and AO 11. The new engine has 120,000km on it.

I appreciate all the help on this matter.

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If he installed the used engine as-is, there's no way to know WHAT happened to that engine before you. It might have been in the salvage yard BECAUSE of an overheat before it got to you. Did your mechanic change the head gaskets? Did he Timesert the block? I doubt the block is cracked, but with a used engine, who knows what the previous owner did to it.

If you let us know what your mechanic did to it before he installed it (if anything), that might help narrow the situation down. If it was installed as-is, I'm afraid there's not much to do now but take the engine BACK OUT, determine what the overheat is coming from (likely head gaskets) and replace 'em...and Timesert the block in the process.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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There have been many topics here on overheating and a variety of solutions.

I had a similar overheating problem that I eventually discovered was a head gasket/pulled head bolts.

The definitive test for my problem was to pressure test each cyl.

125+ psi applied through the spark plug hole.

On one cyl it produced a substantial amount of bubbles in the coolant.

I hope you have a simple solution to your overheating.


2008 STS V8
2016 Colorado Z71
1970 Corvette LT-1 Coupe

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The engine was dry, it takes a couple of cycles for it to purge out the air and fully pull in the coolant. I would have started it let it run till it got hot and shut it down to fully cool then run it again, did you do that or was this overheating on the first startup?

What worries me now is that you put pure water in it, check your coolant concentration and bring it to 50/50, check the air purge hose to make sure coolant comes out also.

What codes did you get when the check engine light came on, overheating?

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You should also replace the thermostat with an oem. If an engine is replaced with a used one, that would be a cheap but important part to upgrade to new (along with a fresh 50/50 mix water/coolant, new oil & filter, new air filter, new serpentine belt, new water pump belt) before starting.

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The engine was installed as is with nio modification. The car was not overheating at the first start up. The mechanic had already taken the air out of it when I started driving it. The car only over heated when I breifly revved it up to 4500RPM. When you drive it at low RPM it's ok. I guess the best test now is to pressurize each cylinder to 125 psi.

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