Just did a compression test on my 98 xj 4.0 aw4 136k miles

results:

1,2,3,4,5,6

90,120,120,120,120,90

I have been reading about what patterns (adjacent cyllinders, etc) mean with low compression, but havent found any with opposite cyllinders. And in general isnt 120 kinda low too? Hoping my engine isnt tired after only 136k

I was wondering if anyone has done the test with adding oil into the cyllinder then testing to see if the rings seal? or if this actually works?

Any help appreciated

 

id be more wolrried about the 90s

 

search compression test how to

 

squirt just a little bit of oil in one of the cylinders... and see what it is.... if it jumps up alot... then your rings are wore.... and thats what it sounds like.....

 

90 is too low.

Are you getting a Check engine light?

 

no, no check engine light. Im hoping its something with the exhaust valve as i hear a tapping noise sometimes at idle. i will try the oil test tomorrow and figure out if its the rings

 

make sure throttle plate is help open during allcyl test turn over at least 5 times per cyl test

 

Engine must be up to full temp all plugs out hold the pedal to the floor and crank for 8 seconds, do a the cylinders and note the numbers this will be your dry test. Add a table spoon of oil to on cylinder at a time and record these numbers this will be your wet test. You want to be better then 150 psi dry and about 180 to 190 wet would tell you bad rings. You can buy a leak down tester to help you find for sure where your loosing pressure. I had a car that did 30 dry 65 wet found egg shaped exhaust valves, most people need to do these test to help them from wasting money on tune up. Proper diagnosis saves money in the end.