[clint699]

i have a 99 grand cherokee with a 4.0 inline 6 with about 110,000 mi on it. i have oil leaking from right side of motor where head mates to block.could this be head gasket? i hope its not the head itself if anyone has ideas i would appreciate it

[jamnjeep]

it could be just leaking from the valve cover in the back and just looks like its the head gasket. Clean the engine real good and take another look. Im pretty sure thats whats mine is doing.

[ARJeepNerd]

Not sure if it's totally relevant, but the old 258s are bad about seeping oil around 5 & 6 cylinder from the head gasket. The one in my CJ is a miserable ***** for not wanting to hold in oil back there.

Definitely agree that the cleaning and valve cover inspection is the place to start though, that valve cover gasket blows WAY more frequently than the head gasket.

[Mopargearhead]

Originally Posted by clint699

i have a 99 grand cherokee with a 4.0 inline 6 with about 110,000 mi on it. i have oil leaking from right side of motor where head mates to block.could this be head gasket? i hope its not the head itself if anyone has ideas i would appreciate it

Do you know if the head has ever been off the Jeep? If it has and the old head bolts were used that would be the cause of the leak. The head bolts on the 4.0L are one time use. If head work is done and the old bolts are used the head will literally lift off the block slightly and spit out oil. I would do as suggested and clean the engine very well and recheck.

[JrMechanic]

Originally Posted by Mopargearhead

Do you know if the head has ever been off the Jeep? If it has and the old head bolts were used that would be the cause of the leak. The head bolts on the 4.0L are one time use. If head work is done and the old bolts are used the head will literally lift off the block slightly and spit out oil. I would do as suggested and clean the engine very well and recheck.

While the head bolts are one time use (TTY bolts), many people reuse them without any ill effects (not that I recommend reusing them however.)

To say that the head lifts up from the block from reusing head bolts is just plain dumb. If this were the case, you would be spewing coolant, losing compression, ect. It would be a mess. However it is possible to blow a head gasket around an oil passage close to the edge of the block allowing oil to seep out. I'd look at the valve cover and distributor shaft seal before assuming it's the head gasket though.

[Mopargearhead]

Originally Posted by JrMechanic

While the head bolts are one time use (TTY bolts), many people reuse them without any ill effects (not that I recommend reusing them however.)

To say that the head lifts up from the block from reusing head bolts is just plain dumb. If this were the case, you would be spewing coolant, losing compression, ect. It would be a mess. However it is possible to blow a head gasket around an oil passage close to the edge of the block allowing oil to seep out. I'd look at the valve cover and distributor shaft seal before assuming it's the head gasket though.

Oh I'm sorry, I forgot you know everything. My old mentor at the dealer who just so happens to be a master Chrysler and master ASE tech told me about this happening. They had an inexperienced tech who did a head job on a 4.0L that all of a sudden had a mysterious oil leak when he was done. He asked the tech if he reused the old head bolts and he said yes. They put the Jeep on the lift and had him power brake the engine. As he did this the corner of the head in the back side lifted ever so slightly and started spewing out oil. The guy pulled the head off, replaced the head gasket, and used new bolts and guess what? The leak went away! Oh well I guess I will go take my dumb comments and go elsewhere. Toodles!

[JrMechanic]

Originally Posted by Mopargearhead

Oh I'm sorry, I forgot you know everything. My old mentor at the dealer who just so happens to be a master Chrysler and master ASE tech told me about this happening. They had an inexperienced tech who did a head job on a 4.0L that all of a sudden had a mysterious oil leak when he was done. He asked the tech if he reused the old head bolts and he said yes. They put the Jeep on the lift and had him power brake the engine. As he did this the corner of the head in the back side lifted ever so slightly and started spewing out oil. The guy pulled the head off, replaced the head gasket, and used new bolts and guess what? The leak went away! Oh well I guess I will go take my dumb comments and go elsewhere. Toodles!

I believe the oil leak took place, but it wasn't from the head "lifting." Using the old TTY bolts will result in uneven force distribution along the sealing surface, causing irregularities in the gasket. That's where the leaks come from