Lower compression in cylinder 2 and 3, + other problems....

[1974CJ5]

I have a 1987 MJ with 2.4 liter and ax4.

I have rebuilt the engine, and put it in the truck to find that the head gasket leaked out the rear of the head due to a score leading from the water jacket to the exterior of the motor. So I had the head gasket resurfaced (again) and put new head bolts in it and torqued to spec.

(During the time I was testing before I found the original leak, I found that the truck had an erratic idle, have very little power when climbing hills, and misses when relieved of load.)

So now, with a new head gasket on a resurfaced head on a block that was checked by a machine shop to be straight and good to go, it seems to be leaking at or around the second head bolt from the front on the intake side of the engine. I can't tell if its a freeze out plug or an exterior head gasket leak again. The missing and lack of power are still present.

So I performed a compression check and found the following: (a wet test was not performed because one of my friends apparently needed my hand can more than I do and it was frikkin cold out so I didn't do much searching for an alternate means of performing it.)

 

Cylinder #1: 141

Cylinder #2: 121

Cylinder #3: 120

Cylinder #4: 138

 

With the middle two cylinders being lower, that would lead me to believe a failed head gasket between them. (note: I have no evidence of coolant in oil just for the record) I would however think that the compression would be even lower in these two cylinders if the gasket failed between them. I am planning on performing a leak down test on the engine soon, to see if I can detect air in the other cylinder from the one being tested.

 

So does anyone have any thoughts as to what the culprit, or culprits are to the various problems I am having? I am about to push the darn thing off a cliff while its on fire :headpop: .

[Geonovast]

You would probably have closer to 30 or 40 psi in them if you'd blown out the gasket between them. 120 is still in spec.

[JeffN]

I know on the 4.0 some headbolts need threadlocker to seal the bolt holes, I am not sure on the 4 cyl. something to check, maybe your leak is the headbolt threads themselves

[1974CJ5]

Thanks for the reply. On the 2.5 four banger it is the driver's side closest to the radiator that get the thread sealant... This one seems to leaking near/at the next one towards the firewall. Can the intake manifold leak coolant near that area? I am not sure how the coolant is routed through the intake manifold I assume it would have to be cracked to leak, but I am not sure...