Hot/Cold Compression Test Engine Temp??

[Thomas M]

Regarding the "hot" compression test............

My head temp checks out at, say, 165 degrees F(using an infrared thermometer) when I stop the engine in my driveway. The shop replaced rebuilt injectors using the copper Permatex anti-sieze compound. I can see it oozing a little around the injector base where it meets the head.

What would be a good head temp at which to remove the injectors in order to do the compression test?

Should the injectors be removed one at a time or all at once?

After the hot test, I would do an overnight cool down and test all cylinders cold.

[bscutt]

I removed mine all at once - makes the starter crank faster. As for temp it's hard to do this with the engine truly hot and not get burned but if you do it within 30 minutes of driving (warm weather of course) it should still be warm enough to get a good "hot" reading.

[Thomas M]

I removed mine all at once - makes the starter crank faster. As for temp it's hard to do this with the engine truly hot and not get burned but if you do it within 30 minutes of driving (warm weather of course) it should still be warm enough to get a good "hot" reading.

Is there any issue regarding the injectors being seized in the aluminum head with the temperature so high? I've noted that there is copper anti-seize compound on the threads, so maybe it's not an issue. I don't want to do any damage to the aluminum threads.

I've never removed plugs or injectors from a hot engine.

[Fatmobile]

I keep thinking copper antisieze isn't supposed to be used on aluminum.
Read some of the threads about not pulling away from the head, don't pull the injector forward or you can break the thin aluminum out from the front of the head.

[bscutt]

yes try to arrange your ratchet or breaker bar so that you are pushing the handle towards the head to break it loose. In a perfect world a T handle would keep from exerting sideways pressure on the threaded hole and cracking the aluminum but I have found that just carefully pushing towards the head while holding the extention steady is a pretty safe way to go.