General question on replacing mounts and HB

Hello All,

I have a 1999 XJ 4.0 Limited (Automatic transmission /4WD) with about 188k miles on it. I've had this car for 12 years and it is my daily driver. Recently it broke down on me and made me realize there are probably many things that need fixing.

I am new to major car repair (worked in mechanic shop when I was 16 and learned the basics of maintenance) and so I have been lurking these forums looking for things to fix. So far I have changed my valve cover gasket, spark plugs and cables, as well as distributor cap and rotor.

Next thing on my agenda is motor mounts (going with brown dog rubber).

While researching on this I have decided to go ahead and replace transmission mount and harmonic balancer at the same time.

I've done lots of research already and am making this thread as a kind of placeholder in the event I run into issues.

Before I start though - I am curious, what order would yall recommend I go in?

Here's my understanding:

1. Remove radiator and shroud to access HB
2. swap HB
3. Loosen transmission mount
4. slightly jack up engine at oil pan with a piece of wood between to take pressure off MM.
5. replace MM one at a time (does it matter which side first?)
6. tighten new MM all the way
7. replace transmission mount
8. lower car back down
9. tighten transmission mount?

Or can I put car back down after relacing MM and then replace transmission mount?


I know I am probably being overly cautious, but this is the first "major" car repair I will be doing alone - and I don't want my GF to come home and find my dead body smashed under a motor. :angel:

I appreciate any advice yall can offer. I am sure I will be posting more questions as I research. I don't be doing this for another week or two.

Edit: just saw the sticky about getting question answered faster. I'm not sure what axle/transmission I have - but I will be sure to figure that out before posting more specific questions.

Are the harmonic balancer and mounts known to be in need of repair? what led you to this conclusion?

You have the steps right, I don't know exactly how to torque the MM down (with engine weight, without??), but you missed the most important step:

10. Celebrate with beverage of choice.

I know my motor mounts are bad. A colleague pointed out that when I start my engine it shakes the car sideways and makes a loud clunk, indicating its lifting up from the torque then dropping back down when done. I grabbed a flashlight and checked em out, and you can see the rubber is pretty much gone. The bolts look fine but the rubber (bushings?) look to be done-zo.

As for harmonic balancer - I do not know if it is faulty but I figured I may as well replace it. I have a lot of vibration in my car along with the occasional squeak from the timing belt when starting up. I replaced the timing belt about a year and a half ago so I don't think its that. My research online indicated that the HB is known to go bad after a certain amount of time and that it can do major damage to your crankshaft over time, so it is best to replace it ASAP if it is bad.

Given that this car is at 188k miles and nearly nothing has been replaced - I figured I would swap as many things as I can. Plus, I've always wanted to learn how to work on cars, and now that I have a garage I am turning my Jeep into a project car of sorts and upgrading as much stuff as I can. My eventual goal is to pretty much rebuild the whole thing over time. I <3 my XJ :loveu:

My current list of fixes for the next few months:
motor mounts, transmission mounts, wheel bearings, u-joints, realignment of TDC (and new distributor if needed), fuel injector swap to the 4-hole "upgrade"

As for the most important step - can't believe I forgot to add it to the list! I will definitely be celebrating 10 fingers and a smoother ride with a nice bourbon.

First, spend $7.95 at www.PacificCoastManuals.com and get a genuine Jeep Service Manual. The manual will explain in great detail the exact steps to test/repair/remove/replace/adjust absolutely everything in and on your Cherokee.

The radiator does not need to be removed to replace the harmonic balancer. The engine mounts and trans mount are seperate jobs, finish one and then start the next.

Tim_MN said:

First, spend $7.95 at www.PacificCoastManuals.com and get a genuine Jeep Service Manual. The manual will explain in great detail the exact steps to test/repair/remove/replace/adjust absolutely everything in and on your Cherokee.

The radiator does not need to be removed to replace the harmonic balancer. The engine mounts and trans mount are seperate jobs, finish one and then start the next.

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I have a Haynes manual - same thing right?

Good to know on engine and trans mount. Thanks

Haynes and Chilton's are worthless once you progress beyond oil changes and brake jobs. They are full of mistakes, and leave out lots of critical information. They are best used to soak up oil spills.

ok cool. I have been looking through my Haynes and did not feel like it was that helpful. I will definitely pick up the FSM

The Brown Dog MMs will come with extremely detailed instructions, including which side mount to do first and when to tighten what. And they are well written by a native English speaker.

Perhaps I should qualify the above as applying at least to the complete motor mount and block bracket kit. I went looking to see if they have a link to their instructions. I did not find a link, but for the complete kit they have a statement that they can email you the instructions in advance, but there is no such statement for the motor mounts by themselves. Not having ordered the mounts without the brackets I cannot speak to just the mounts.

I would not hesitate to ask Brown Dog if there are any questions.

Also note that Brown Dog offers a discount.

Brown Dog's motor mounts come with easy to follow instructions, I used their poly mounts (which are great but you definitely feel the engine vibes). The biggest PITA will be lining the mounts up to get the bolt through but just have a little bit of patience.

I've been googling around trying to find a definitive answer. I know people say to use a jack with a 2x4 and place it under the oil pan to lift the engine just enough to take pressure off the bolts.

But is it better to use a bottle jack or floor jack? I read somewhere that a floor jack will move your engine as it raises it and put everything out of alignment, and so its better to use a bottle jack.

Thanks!

shmicah said:

I've been googling around trying to find a definitive answer. I know people say to use a jack with a 2x4 and place it under the oil pan to lift the engine just enough to take pressure off the bolts.

But is it better to use a bottle jack or floor jack? I read somewhere that a floor jack will move your engine as it raises it and put everything out of alignment, and so its better to use a bottle jack.

Thanks!

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I used a floor jack and came in from the side. I dont know about the bottle jack. I will advise this: use a sturdy piece of wood for your bracing, you dont want to have the pressure crack a cheap piece and cause uneven pressure on the oil pan. that would suck. I used a 2x12 pressure treated and even it cracked... of course it was a little bowed. If I had to do it again I would probably double up the boards for overkill.

You are over thinking things... a floor jack swings on an arc... but your lifting the motor an inch....

YOU ARE OVER THINKING THINGS!

Also, replacing a harmonic balancer "because you have vibrations", when you know for a fact your motor mounts arent good anymore is downright idiotic.

**** it, use a scissor jack, or take it to a mechanic named jack...

I've never tried to jack the engine by the pan. I have jacked one many times with a piece of wood on top of the pan bolts.

xcm said:

You are over thinking things... a floor jack swings on an arc... but your lifting the motor an inch....

YOU ARE OVER THINKING THINGS!

Also, replacing a harmonic balancer "because you have vibrations", when you know for a fact your motor mounts arent good anymore is downright idiotic.

**** it, use a scissor jack, or take it to a mechanic named jack...

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hah alright. I'll visually inspect my HB before replacing... EVERYONE WAS A NOOB ONCE

shmicah said:

EVERYONE WAS A NOOB ONCE

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Don't pay attention to him. Something happened to his grandmother. "Stupid questions" are relatively painless ; stupid actions are not.

Ok, I started on my motor mounts yesterday and WOW... what a PITA. Sorry for the long post here but bare with me please. I think something is wrong with my car and would like some input.

I spent about 7 hours and only got the driver side done.

First, yes I did a ton of googling and research about how to properly do this. I put a jack under my oil pan right on the X with a block of wood between. Removed the 4 nuts from the transmission mount through the skid guard. Pulled the airbox out and had good access to the DS MM. I was able to get the bolts connecting the mount to bracket and frame with no issue, but I could not get the crossbolt all the way out to save my life. I tried moving the jack up and down a half pump at a time starting from the very bottom all the way up to a few inches then back down to "resting". It was stuck halfway, so it seemed it was being pinched between the bracket and mount.

Finally I took the whole bracket off, and when I did this, the whole (mainly backside) engine shifted downward on the DS an inch or so. Put the new MM into the bracket, put the whole thing back in to the engine and could not get the damn thing to line up. I was a good 1-2inches off at like a 45 degree angle. No matter how much or how little I jacked my motor, the gap would not come within an inch. The MM was higher than the bracket by a few inches.

Finally I went and got a bottle jack and a 2x4, jammed it up on the DS of the oil pan bolts between my oxygen sensor and oil pan, and jacked it up there hoping to lift the rear DS of the engine to make everything line up.

Here is where I have a question.

Everyone says you barely jack up the engine and that in reality you are just letting it rest on the jack. I had to jack the shit out of my engine, to the point I was lifting my car and it was making loud creaking noises. This is after hours of trying to go from barely touching the oil pan and lifting like a half pump at a time with my little 2 ton bottle jack. It would never line up. Finally, it was like 9PM and I was pissed so I jacked it wayyyy up and it finally came close enough I could use a mallet and beat it into submission. When I finally let it off the jacks, my car sank back down a good 3-4 inches but the valvecover/engine looked like it was lined up nicely and no longer leaning.

I noticed that where my exhaust pipe comes down between the intake manifold and engine and bends 90 degrees back towards the rear of my car has a huge crease in it. And it doesn't look like a machined turn, it looks bent. Do you think my MM were so shot on DS that the engine sagged and bent the exhaust? And that this was kind of holding the engine down, and as I was trying to jack it up it was "stretching" that bent pipe back out (hence all the creaking and popping?). My engine was leaning hard to DS/back of car and the MM disintegrated as soon as I touched it. The other theory I have is that someone rear ended me in a parkin lot, and hit my exhaust tailpipe which pushed it in at that bend under the engine and creased it.

I will take a picture of the exhaust and post later today to help explain, but has anyone seen this before?

SIDE NOTE: A few years back I got an oil change, and when I picked my car up, a fan in the front of my engine was hitting a shroud. When I accelerated it would be very loud. I took it back to have it fixed, they didn't, but I had to drive cross state so I said screw it and drove until the shroud broke (I know). Could this also be a symptom of my distintegrated MM?

Thanks for your help

Ok, did more searching and found this thread:
http://www.jeepforum.com/forum/f11/cherokee-bent-exhaust-pipe-144061/

sounds like it comes that way and is for axle clearance?

I'm still curious as to why I had to jack the shit out of my engine to get my MM back in. Am I doing something wrong? I really don't want to go through this again on PS.

Sorry I missed responding to this. I can't help on the exhaust bends but I had to Jack the shit out of my engine too because the old mounts were shit. I used a round pry bar end to line shit up for the bolts. I hope you got it all sorted.

2T2-Crash said:

Sorry I missed responding to this. I can't help on the exhaust bends but I had to Jack the shit out of my engine too because the old mounts were shit. I used a round pry bar end to line shit up for the bolts. I hope you got it all sorted.

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No worries, I eventually assumed that was the reason but good to know for sure. I was able to use two 2x4s on PS and jack on the bracket. Was a little more ballsy this time and went straight for it. Was able to get it all lined up without needing to remove the bracket.

A short tapered drift pin helps line up the holes to ease bolt installation .