Long story short, just bought a DA with 200k miles and known bad head gasket (milky oil, white smoke, and loss of coolant).
How would I check the health of the motor with a compression test even though the readings wont be exact because pressure would leak through the head gasket?
Visual inspection of cylinder walls? Tear down?
Always the option of a new motor swap too since the old motor is already at 200k.
well do a cpmression test anyways… PSI reading will tell you what cylinder the leak is on… you can also do a leakdown test to asses condition of the rings on the remaining cylinders.
only way you would be able to really ascertain anything about the motor in concrete would be to fix the HG, then do all the typical test to get a better idea as to overall health of the motor. then again it could be reasoned that it may just make sense to grab another motor or just do a rebuild since you are gonna have the head off and be halfway into the block anyways lol…
As you have to pull the head anyway to do the HG, it is easy enough to eyeball the cylinders.
If all looks good, replace the HG.
As mentioned, you will be part way to a rebuild once you pull the head, may be worth rebuilding at the same time, at the very least, [if cylinders look good] have the head done, [valve job, ect.]. 94