Ever since I’ve rebuilt my 4 cylinder, the idle vibrations have been off the freaking charts. Accelerating past 3k, it feels like the engine is going to lift off and take me to orbit.

I should mention that I installed new Anchor engine mounts when I put the engine in, and they were the same ones that I had before I rebuilt the engine, and I replaced them just cause.

Anyway, is there anyone out there who has motor mount recommendations for the 2.5? They’re different than the 4.0 so nothing meant for a 4.0 will fit mine

 

Im not familiar with the 4 cyl...but insane idle vibrations is symptoms of a bigger issue than finding different engine mounts...something is wrong

 

I thought the same thing, but I can’t find anything wrong. There’s no misfires, all the mounts are tight, yet it feels like the engine is sitting on the frame.

the only thing I can really think of besides of new engine mounts is just the internal balance of the engine. I don’t know if putting 60 over pistons in it set off the internal balance, or if that’s a negligible difference.

 

I ran browndog mounts on my 4.0 and can't speak more highly of them. I would recommend going and loosening the mount cross bolts on the engine and the mount on the transmission just slightly and taking a short drive up and down the drive way. It lets the motor "settle" into the new mounts. When I first put the browndog's on I had to do this and the vibration dropped a good amount.

 

trans mounts can be problematical on the auto.

On one occasion, I replaced my worn OEM with a Rock auto cheapy.

My XJ sounded like a machine gun (trans rattling)

I took the mount out, and comparing to the old one, I bounced my 180lb up and down.

The old one had no give, the new one was like a tennis ball

In my opinion, OEM type mounts all round should last 10yrs/100k miles and have minimal vibration

uprated mounts do not normally reduce vibration

 

I went ahead and pulled the trigger on the brown dog motor mounts. I had no idea they made mounts for the 2.5, and apparently their “ultra flex” mounts that are for the 2.5 are designed to lessen the vibrations of the 4 cylinder, because boy are they violent.

 

Do you have any recommendations for a good trans mount? I have the AX15 behind my 2.5, so whatever works with the 4.0 will work with mine.

I got the same mount you said was a RockAuto cheapy, so I’m wondering if I get a “soft” mount if that’ll help

 

too soft or too hard are both bad in my opinion

the trans mount should not give when you jump up and down on it

I would fit OEM type from Rock Auto (which I did, no more problems, fitted OEM mounts all round)

An I6 is an inherently balanced engine, while a 4 cyl is not, so additional NVH measures may be justified

 

I don’t really know what brand is OEM anymore. It seems that they’re all the same now. But the mount I got, which is Anchor, seems as hard as a rock, which might contribute to the vibrations I’m feeling

 

true, seems like they are OEM style though.

I fitted Mckay brand locally made, cost a bit more, say they are OEM spec

Perhaps you would be best served determining if there is some balance problem with the motor, can be caused by a cylinder problem, such as partial misfire, bad head gasket or harmonic balancer etc

Does it visibly shake when idling. It shouldnt

I would start by pulling plugs one at a time with engine running, and see if one in particular has a less noticeable effect on running (dont shock yourself)

A compression test is also easy on a 4 cyl ?

I had a vibration issue on an engine so many years ago, I cant even remember what the **** it was, but I did have to replace the cylinder head

 

It sounds like a balance problem , is it a auto trans or a 5 speed trans and did you change anything there ? maybe clutch or flywheel ?

 

Look at stinky fab racing I just literally just installed their transmount.it cost me about 125$shipped,the quality was really good.All around great product.i had an issue with my mount being assembled for center mount,I needed the offset.so just be mindful about the orientation of yours when you take it off.They also offer motor mounts,id assume they would rival brown dog?but idk of anyone that had bought these personally..I may buy a set and report back.

https://www.stinkyfab.com/products/s...ep-xj-cherokee

 

It’s probably not your mounts. I don’t not what rpm I’m at because I don’t have a tach but I take third all the way to 65 to pass up a hill and don’t get the engine vibrations you talk about. I have two anchor doan installed. Also the AX4. I see you went and put the upgraded 5 speed in yours. It could be related to that swap I would imagine.

 

Yeah, I think it might be. I used the Jeep 2.5 flywheel instead of the Dakota 2.5 flywheel because I couldn’t find one. I’m thinking that if I do find a Dakota 2.5 flywheel then I’ll slap that on when I redo my rear main seal. I think the Dakota flywheel is slightly larger, but I don’t know if that would create a balance problem.

 

I am under the impression that there is a tone ring on flywheels / flex plates that the CPS use to determine crank position. Not sure that you could run with a Dakota flywheel. I know I had to swap my flywheel along with the distributor, intake manifold, etc. to run a 91 long block in an 88