B7200 low compression

[YjJeep]

Did a compression check the other day on my b7200 and it was low in the front two cylinders (250-275), it did have a chance to cool off some but was still warm. Ran ok once warm, but was extra loud and hard to start cold (65degree garage) found some valve marks on the piston in front and in back.... Back was over 300 (highest my gage goes)

 

[D2Cat]

Looks like you have some rod bearings giving up, allowing the pistons to move too far.

 

[CountryBumkin]

Are your sure the valves were adjusted correctly?
Too bad you pulled the head already. A "cylinder leak down" test would have told you if the rings were leaking excessively or if the low compression was due to valves (worn or adjustment).

Of course if you have bad bearings then it needs to come apart anyways. And if it's coming apart, I'm sure you will replace the rings and hone the cylinders, and have the head checked/rebuilt.

BTW, be sure to check for bent pushrods.

 

[YjJeep]

Yea should be simple enough to do the crank bearings and rings/ hone it. Didn't think of doing a leak down that other day