Replaced engine mounts

Hey guys just replaced my engine mounts with OEM in my 91' 4.0 HO w/AX-15. I did all three and really didn't have much trouble at all. Everything is torqued to spec etc. I re-checked the mounts to make sure they didn't tear etc. Now here's the thing... Whenever I shift out of 1st to 2nd and 2nd to 3rd, I get this weird rubbing noise (@ 1500 to 2000 revs) that seems to go away as the engine warms up.

It didn't do it before I replaced the mounts. I thought that it might be the manifold or something exhaust related but can't find anything to suggest this is the problem. Like I said its a rubbing noise almost like tire rub... I know I saw a post on this too, but can't find it. Can't figure it out. Any thoughts on this would be appreciated.

Cheers!

Marty

'91 2 Door Sport... 242k KMs... No Mods til I find a 4 door!

You need to change the transmission mount when you change engine mounts. The 3 mounts support the engine & transmission. My dealer parts guy told me they replace all 3 at once. If you do not then the old mount remaining will be worn out in an accelerated pace.

You may of borken the trans mount. Go buy a new trans mount and install it.

martin said:

You need to change the transmission mount when you change engine mounts. The 3 mounts support the engine & transmission. My dealer parts guy told me they replace all 3 at once. If you do not then the old mount remaining will be worn out in an accelerated pace.

You may of borken the trans mount. Go buy a new trans mount and install it.

Click to expand...

The guy said " I did all three and really didn't have much trouble at all."

bzdel2441 you are good at pointing out my overlooking the comment BUT you are doing NOTHING to help CDNXJ to solve his problem, do YOU have anything to help out our fellow XJer????

On the rubbing sound take a look at your raditor, see if the mechanical fan is rubbing the radiator. The new mounts may of changed the angle of then engine or the height in the engine compartment. You have changed the geometry of the engine to the chassis relationship.

Also are you using mounts from the dealer or a parts store? Did you use a urethane mount, a change of mount material could explain a difference in vibrations which may seem like a "rubbing" sound. I remember when I changed my rear mount and I placed it next to the new one there was over an inch of difference in height.

I noticed on my XJ the hanger for the exhaust was broken and I replaced it. You may have the exhaust hitting now. It can be found, just have to figure out how ot make it happen so you then try things till it goes away.

Sorry Guys I didn't get back sooner... Just to clarify, I replaced all three: 2 x Engine Mounts and 1 x Trans mount. They are Mopar mounts... I did see a post here that updated the torques so I did that. Martin I actually followed your write up on replacement, and you were right its not that bad, just not something I'd want to do all the time. It's funny that you mention the rad, as on Monday my brand new rad (3 months old) ruptured at the drain plug. I replaced the mounts on Saturday. Thank god it was replaced on warranty. I checked both the old one and the new one for signs the mechanical fan was rubbing and it isn't.

Like I said I thought that it was exhaust related... But I'm not convinced... I was wondering if I could have done something to the trans when I lifted the engine to change out the mounts... I was gentle and used alot of caution when doing it... I don't know maybe I'll wait til something falls out like the tranny LOL!!!!

It happens when the engine is warming up... 1st and 2nd gear between 1500 and 200 revs.... Again thanks for any ideas...

Cheers!

Marty

'91 2 Door Sport... 242k KMs... No Mods til I find a 4 door!

sounds very similiar to my thread except in my thread i partially fixed the prob by replacing the mounts. I say partially because its there a very small bit at 2500rpm...take a look.

http://www.naxja.org/forum/showthread.php?t=49361

Thanks jeepsrock; I had read your post before. I know I saw another one that had something to do with this. I'll keep looking, I'm not entirely unconvinced that it isn't manifold/exhaust related.

I'm also going to go thru and re-check/torque every nut and bolt I can find under there, for the 3rd time... Again if anybody has ANY other ideas I would greatly appreciate it.

Cheers!

Marty

'91 2 Door Sport... 242k KMs... No Mods til I find a 4 door!

The exhaust downpipe rides so close to the engine ... check to see if that is rubbing against the oil pan.

martin said:

You need to change the transmission mount when you change engine mounts. The 3 mounts support the engine & transmission. My dealer parts guy told me they replace all 3 at once. If you do not then the old mount remaining will be worn out in an accelerated pace.

Click to expand...

Anyone have a different opinion on this? I can see a dealer or shop doing this, because they want to get rid of the vibe and just make sure the job is done 100% correct and no come back later to complain fix it for free a 2nd time.

Often the trans mount doesn't get a lot of flex, maybe that different for an XJ or any 4WD.

My motor mounts are worn out ('95 XJ 2WD, 2.5L I4, AX-5), they are squished and the drivers side is chunking out as well. As well, I get a lot of motor rocking with throttle changes, the shifter rolls left and right in my hand with throttle changes. But, the trans mount looks perfectly fine.

I've got a new Passenger side Mount from NAPA and Driver's side Mount on the way from Discount Jeep, it was labeled OEM mount.

Do I really need to change the trans mount as well? Even though mine looks fine, I've replaced only some of the mounts (the worn out ones) on motors and left the good mounts before and everything worked fine. Both FWD and RWD, but never have on an XJ.

The new firmer mounts may just transmit a bit more vibration or vibes at a different frequency than the old worn ones. You might be more sensitive to the "new" noises. I put in a poly trans mount and had more vibration than before and was worried until I figured out why and where it came from. Now I don't hear it anymore. It is possible that the motor or exhaust shifted a tiny bit during the work and something just needs to wear in and adjust itself to the new position. Look for any contact points and check that everything is tight.
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I would change all 3. The mounts fail because of age and contamination from oil and tranny fliuds. You are already dirty, just do one more and you won't have any worries.

Check to see if the front exhuast pipe is riding on the bracket for the motor mount. I changed my mounts and had that problem. I took the bracket off the frame and grinded it down a bit to give the pipe a quarter inch of clearance.

I hope he's still not hunting out for answers as it's been a year since his post

I didn't even noticed that... I just say that it was up at the top... All I can say is I'm not the one that replied to it to bump it up.