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Head Gasket install


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ok so I'm about to pull the head off my 88MJ 4.0L. i have done head gaskets on other trucks but they were small block 350s. is there anything i should replace and are there any strange hang ups pulling the head (think E12 reverse torx bolts on the tranny) :mad: that i should know about. thanks

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I just got done doing the head on my 90. I would recommend getting a Chilton's or Haynes to do it, but it isn't necessary.

 

There wasn't anything in particular that I had trouble with. The only thing that bugged me was trying to torque the intake/exhaust manifold bolts on the underside of the intake. There is just no way to get a torque wrench in there.

 

Make sure to use a good gasket, and replace all of the gaskets you can get to since you have pretty much everything off.

 

Don't make the mistake I did and not put the rods and rockers back on before you put the valve cover back on...

 

Other than that, it just took me a bunch of time to make sure everything was done correctly.

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Just redid the head on a 4.0 also, but it's on a stand not in the vehicle. I agree the lower manifold bolts are a PITA (even on the bench!). You don't need to mess with the bellhousing bolts at all unless you are pulling the engine to do the work.

 

Do not use any type of sealant on the new head gasket, and there is a specific torque sequence and set of torque steps to follow when reinstalling the head. The #11 headbolt (front of engine, driverside) needs sealant on the threads because it passes thru the water jacket, and it also only gets a final torque of 100 lb/ft, not 110 like the other ones.

 

For the headbolts on the driverside, you'll need a deepwell 6 pt socket (can't recall the exact size of the headbolts at the moment, I think they are 5/8"). You can reuse headbolts one time, and if you do you should dot the tops of them with white paint as a reminder that they are on their second tour of duty. If yours already have marks on them, do not reuse them.

 

Jeff

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Coat the threads of the stud bolt in the # 11 position with Loctite 592 sealant, or equivalent, before installation.

Tighten all cylinder head bolts to 29 Nm (22 ft. lbs.) torque using the tightening sequence.

Tighten all cylinder head bolts to 61 Nm (45 ft. lbs.) torque using the tightening sequence.

Recheck all cylinder head bolts at 61 Nm (45 ft. lbs.) torque using the tightening sequence.

Tighten all cylinder head bolts (except # 11) to 149 Nm (110 ft. lbs.) torque and tighten bolt # 11 to 135 Nm (100ft. lbs.) torque using the tightening sequence. NOTE: Clean and mark each bolt with a dab of paint after tightening. Should you encounter a set of bolts which were painted during an earlier servicing operation, replace them.

Connect the battery negative cable.

 

 

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