Bad intermittent knocking sound after overheating

[jasonlee]

I wasnt sure where to post this, but this is my best guess.

anyway, I recently did some work on my friends car, changed the lower end. its a 2g with the following basic mods: bushur upper IC pipe, balance shaft removal, and a few other dress up items basically.

Somehow he overheated it on the interstate, crusing at 70-75mph. He told me he pulled over and shut it off before the stock temp gauge got into the red but it was climbing fast. when he pulled over it was boiling out of the overflow tank.

I went over and checked it out today, its starts fine, and idles great, but when you rev it, or it changes rpm/s quickly there is a bad knocking sound that comes and goes.

we took it for a short drive, no boost, and the knocking sound was apperent, but not constant... again it came and went.

to me it sounds like its comming from the upper half of the engine....

What should I start checking to replace?

J

 

[RavenX]

Do a compression test and go from there. Drain the oil and check for metal flakes just in case. It kinda sounds like rod knock. You might have to pull the oil pan check for flakes that way. Other than that your going to have to pull the head and check for everything else that way. So good luck. Usually the compression test will tell you whats up.