the elthe

Hello all!

I am new to the forum, so I may have missed the answer to this problem. I have a 1998 Jeep Cherokee Sport, 4-liter engine.
The engine overheated, warped the head, broke #1 piston, got a good used head. Replaced piston, and all rings and rod bearings.
There is no compression on any cylinder but #5, which is within specs. Timing's right on, all other mechanics check out.
Any ideas gents? Been battling this for awhile.

Thanks!

belvedere

Did you have the timing chain off?

freegdr

You got used head checked out b4 install?

the elthe

Check and check. Both timing and head are good.

Brian3676

I would re check. It's impossible for timing to be spot on and the head check out good but still have 0 compression on that many cylinders. Was the block machined at all or you just tossed new rings on?

JeepingDan

Do a leak down test on the affected cylinders to see where the compression is going.
Make sure valves are closed and piston is up on compression stroke when performing the test on each cylinder.

belvedere

Agree. I'll ask again: was the timing chain off?

cruiser54

Excellent question. No frickin' answer. How's your Jeep running, Belvedere? Mine's running great.

karl4x4

When in doubt with compression as to: is it the rings or the valves that leak?
Squirt a little engine oil in the pistons, rotate engine once over without the spark plug to ensure you don't have to much oil in. If some squirt out, you know the piston is covered.

Now do your compression check. If it is still 0, your head or head gasket is the culprit. if the compression shot up, its temporary, your rings are either worn or stuck. (sea foam http://www.seafoamsales.com/sea-foam-spray/
Has been known to get rings unstuck when sprayed in combustion chamber and left overnight to soak.

Note: every 4.0 litre rebuilt I did, the rings where ALWAYS stuck to the piston. most times had to break them to get them off.

Note 2: Get the head checked. For the time and trouble of a warped head, its worth the money.

belvedere

Very funny, cruiser. Very funny.

jebmccall

when you installed the rings did you line up all the splits? or did you put them approximately 60 degrees apart? if they were all lined up that will cause low comp

belvedere

Low compression, maybe, but he said no compression. Unless that replacement head and/or gasket are completely screwed up, which I doubt, it's just about gotta be valve timing.

the elthe

The timing chain test has been done. Negative. I believe the block was machined.
As for no answer, I have very little free time away from my job. Hence why it's taking so long to get the Jeep worked on.

belvedere

Which test? Again, was the chain taken off? I just honestly can't think of anything else that would cause 5 of 6 cyls to have no compression, except for valve timing being off.

cruiser54

I'm guessing it was since the block was machined.

This reminds me of that show Columbo. "And yes, one more thing....".