yeti_

To start this is my first post. I have done a good deal of research across multiple forums but have seen a thread with quite the same issue.

I recently bought a 96 xj with 225k runs solid shifts fine but vibrates when in in drive or reverse at a stop. It isn't rattling if is shaking the entire vehicle. I have already replaced all three mounts. ( that helped tremendously) but it did not solve the problem. Where do I go from the mounts?

On a side note sadly I did not get to the problem before it cracked the exhaust manifold. Any suggestion on a replacement part? I've plenty of reviews that describes the woes of buying a new manifold only to have to modify it and the intake just get to fit. I don't own very many tools and this is my daily driver so I would prefer not to be out of commission for long.

I did not proof read this I hope it is... Coherent.

Thanks for any help

cruiser54

Look here to see if the exhaust is closer than a finger width to the crossmember.

yeti_

Yeah I can easy fit my fingers between.

yeti_

would bad leafs or shackles be culprit?

cruiser54

Read this!!

From Jon Kelley aka 5-90 @ www.kelleyswip.com



This is a known issue.

1) Unless you're going to get silly with the skinny pedal, 2xSAE8 screws on one side won't be a huge problem. You'd be better off with three, but if you don't get silly you'll be okeh.

2) The Brown Dog engine mounts use two or three additional holes on each side, and spread the mount/clamping force over more of the block. This is invariably a good idea, and I'll probably be doing it as I refit my 88.

3) The primary reason that the screws snap is because, sometimes, the screw holes in the block aren't drilled & tapped deeply enough. This causes the screw to bottom out in the hole, so you end up torquing against the bottom of the hole instead of stretching the screw (as you're supposed to do. Not your fault - you aren't doing anything wrong.) The screw is not stretched properly, and the head is not butted up against the bracket, so there's some room to move there. Vibration then causes wear cycles on the screw, which generally leads to rupture.

The easy/cheap fix? When you replace the screws (3/8"-16x1.25", as I recall,) put two flat washers under the head before you screw it into the hole.

The check? Take a feeler gage (.003" to .005") and try to slide it under the head of the screw. You'll be able to get under the corners (look at the hex head, and you'll see that the surfaces curve toward each other slightly) if it's a standard hex head - if it's a flanged hex head, you should not be able to get under the head anywhere. If you can slip the gage under the head, you have a problem. If you can touch the shank of the screw, you have a big problem!

In no case should you reuse the screws after you take them out - they'll be stressed under the head, and you'll have a significant reduction in strength. Replace them outright, putting washers under the head as I mentioned before. The washers will make up for the slight lack of depth in the hole (two of them will be about 0.125" or so,) and allow the screw to be preloaded properly.

yeti_

Not sure exactly what the last reply directing toward. I have already replaced the mounts. I am going to replace the leafs next (the appear to be shot). I believe them to be the culprit.

That being said assuming I can find a set of stock leafs in working order I plan to install them with a budget boost package. Any suggestions which package to go with I am only looking for a 2" lift. I need to stuff some 31" under it.

cruiser54

It's in regard to a known issue of the BRACKETS between the motor mounts and engine breaking their bolts.

yeti_

Ill check the mounts again but the brackets coming off the engine seemed pretty solid.

cruiser54

Check the bolts that hold the brackets to the engine block. You need to LOOK at them.

1976gmc20

Wasn't it only certain years (mid-1990s IIRC) that had the shallow bolt holes issue in the engine blocks ???

cruiser54

Who knows? Check them anyways.