drivers side motor mount keeps failing

hi guys, been a while since i have been by here,

i am in the middle of doing some extensive body repairs on my jeep. while i was looking it over i noticed that my drivers side engine mount has failed again, i have replaced this mount 2 times now. the first time i replaced it i replaced all 3 mounts, but i didnt get to the passenger side and transmission mount for a couple weeks. a while later i noticed the same thing, drivers side engine mount failed. i blamed my own stupidity for the failed mount on not replacing them all at the same time. so this time i replaced all 3 all at the same time, as i did my new exhaust manifold,

well now i probably have a cracked new manifold i need to repair, and will probably be going to the brown dog motor mounts, but i need to fond the reason why i keep eating through mounts, on all 3 mounts i have replaced on the drivers side look the same, it eats through the rubber on the top side. i can currently bounce my engine up and down near 2 inches and am definitely not looking forward to doing my exhaust manifold again.

any ideas on what may be happening? and yes i drive it hard, yes i wheel with it, and do not believe it has to do with driving habits, vehicle is a 1999 xj with a 4.0

RD

using cheap mounts and driving it hard will do it. Get some better mounts and put a flex joint in the exhaust to save the next header. Brown dog are good for the mounts.

The factory mounts are not a very strong design. I second getting Brown Dog motor mounts. I ended up with their Poly $90 mounts (driver and passenger). I would suggest skipping the option to order their hardware with it as mine never fit properly, and I reused the old factory bolts/nuts.

The poly mounts are nice because most unibody vehicles have a front crossmember to tie together the front end, besides just the firewall and radiator/bumper supports. The XJ does not have this. The poly mounts help with steering feel/rigidity by reducing some of the flex between both shock towers and the engine and locks everything together, more solid. I'm really happy with mine!

i have inadvertently started doing major body work, found some sections of the body that were rather rotted, i have welded in a bunch of new steel in several areas, also noticed a good sized tear about 3 inches long in the body just behind the rear seat, so i am guessing i had a good amount of unwanted body flex, i am wondering if that could have contributed to the demise of the mounts.

i have 2 xj's that need the mounts, and was thinking of the brown dog's anyway. i will probably redo the transmission mounts at the same time, are there any higher grade transmission mounts you would recommend ? i have a 3" lift on mine, and plan on running 32 inch tires, would i benefit from a 1 inch lift on the mounts ?

RD

alwayzAMC said:

i have inadvertently started doing major body work, found some sections of the body that were rather rotted, i have welded in a bunch of new steel in several areas, also noticed a good sized tear about 3 inches long in the body just behind the rear seat, so i am guessing i had a good amount of unwanted body flex, i am wondering if that could have contributed to the demise of the mounts.

i have 2 xj's that need the mounts, and was thinking of the brown dog's anyway. i will probably redo the transmission mounts at the same time, are there any higher grade transmission mounts you would recommend ? i have a 3" lift on mine, and plan on running 32 inch tires, would i benefit from a 1 inch lift on the mounts ?

RD

Click to expand...

I don't know about others, but I used an OEM trans mount from NAPA and filled it with black Urethane caulk from your local hardware store.

I can also give a good vote for M.O.R.E. motor mounts.

The drivers side mount on my 97 XJ did that too. I attributed it to poor quality replacement and the transfer case drop. The transfer case drop puts extra tension on the mounts. My 01 XJ mounts got replaced around 300,000 with only some "sagging" from age. I used dealer replacements on both XJ's and replaced the transfer case drop with a SYE on the 97 XJ. For hard wheeling, most suggest using Brown Dog, M.O.R.E., or something more stout than the OEM style replacements. I think any mounts you buy from NAPA, Auto Zone, etc. are cheap rubber and prone to failure. I used the dealer parts because I was concerned with extra noise and vibration.

"I used the dealer parts because I was concerned with extra noise and vibration."

My OEM engine mounts are fine at 173k miles. I suspect people who experience type of failure run NASCAR fast, whipping their horse for all it's worth. Pity this poor Jeep.

i wouldn't say i drive nascar fast, rarely go over 100, and usually under 70 down the dirt roads, i too had thought it was abuse, so i was actually gentle on it after the last mount failed, and i haven't even tore through the woods the fields and the mud recently.

i am actually hoping to order my brown dog mounts monday, and hope to have all my panels back on and painted by next weekend. i almost want to try another round of the carquest motor mounts to see if my theory about the additional body flex is accurate,but not unless they go good on the bad ones.and have a feeling they might be just junk, or meant maybe for my mother's jeep, and her driving style.

if i had seen the mount bad again before i did the body work it probably would have been the last straw, and sent it in parts to the scrap yard.so hopefully the brown dogs take care of the shaking i am getting from what feels like the front end. have been chasing that for a while now, and have both times not looked at the "new mounts" will post on how it goes.

thanks for the responces,

RD

Your mounts should be under warranty.. But, I agree on Aftermarket mounts for sure. If you can afford, consider the full kit including the block plates.