I have a 2000 cherokee sport 4.0 and just replaced the head on it with a resurfaced used head. The engine was running rough and misfiring on cylinder 4 and sometimes 5. I replaced the coil pack and that did nothing. Took it to have it checked by a professional and cylinder 4 was running at 20 psi.

Now my question. Can the valves on this engine be adjusted?

Thanks for the advice!

 

Do you mean that you did a compression test and you've only got 20psi in the #4 cylinder?

 

no valve adjustment. I would think something happened to the gasket on reinstall, or the valve isnt seating right.

 

Yes, we had a compression test ran and #4 was weak. We have a lot put into this and I hate to have someone open it back up and rebuild it. I have a friend that will sell me the same engine for $500 and I think that is my bet.

 

If #4 is at 20psi, you have a wrapped head at that point, blowby on that piston, major intake and/or exhaust valves not seating, or you mistightened the bolt in the right order and caused a gap in that spot. The safest bet of the safe bets, unless you want to spend the time in Diaging the compression leak 0which can be a ***** and time comsuming. The best bet is to do your $500 option although the solution to your motor might be cheaper.

 

Was the head new or rebuilt? It is possible it has a warped valve seat. Maybe that is why they were selling the used head to begin with. Did you have it resurfaced or was it resurfaced when you bought it? Did they vacuum check the valves to make sure they were seating? You might be able to pull the valve cover and rocker arms off the valves for that cylinder, put a leak down tester on it and try and hit the valve for that cylinder a couple time with a rubber mallet to try and seat the valve on a different spot of the seat. Just a thought to try before you pull the head back off again.

 

Also you might want to make sure that when the push rods got put back in it got seated down on the lifter and not someplace else down there. Maybe the pushrod went off to the side so when the bridge got torqued down it is constantly pushing the valve open and not letting it seat back down. This should be pretty obvious if you pull the valve cover off and one of the valves on that cylinder is down further then the others.