I want to replace my engine mounts and just wondering which ones to go with. The Jeep will mostly be a daily driver and won't see a lot of extreme use. It is worth it to upgrade to polyurethane engine mounts? I think stock mounts would work okay for my use but I'm not sure how long they typically last. I don't want something that will go bad again in 2-3 years. Will I experience a lot more vibration transmitted to the body with polyurethane?

 

You've asked a good question.
IMO it's a personal choice.

The original motor mounts (aka engine vibration dampeners) were designed to dampen vibrations on highways and streets. The rubber dampening material in stock motor mounts is surrounded by a thin metal strap. They were not designed for use offroad. When used on a vehicle with driveline/engine vibrations or offroad these motor mounts will not last very long. Cheap import replacements are even worse.

Most high performance motor mounts are designed for use offroad. Thus, while they provide some vibration dampening, they will not provide as much as the originals.

That said, high performance motor mounts with rubber bushings will absorb slightly more engine vibration than polyurethane. This is because rubber bushings used in high performance motor mounts are generally not as hard (Durometer scale) as polyurethane.

If you have engine/driveline vibes, you will feel more of them through a high performance motor mount than the original style. If you do not have any engine/driveline vibes, you will not notice a difference between high performance and the originals. Neither motor mount style will reduce vibes caused by cracks or other issues unique to a unit-body vehicle.

Anytime you replace motor mounts, regardless of style, it's very important to loosen the transmission mount. If this is not done, you will damage the transmission mount. We urge customers to replace all three mounts (2 motor mounts and one transmission mount) at the same time.

 

if the stock ones are new the use them but i would go with the poly.

 

Polyurethane motor mounts or trans mounts will last longer, but they will also transmit more engine and driveline vibration simply because they are stiffer than rubber motor mounts. You will notice it even more on a unibody vehicle because you don't have any body bushings isolating the body from the chassis.

 

If I were you I would go with aftermarket motor mounts that way you don't have to work about it again. I suggest ironman 4x4 motor mounts, these are what I have and they are pure beef. I don't see these mounts going out any time soon.

 

I just ordered a pair of the ironman 4x4 fab engine bushings. Cant wait to get them installed.

 

Aftermarket will last longer? My 97 original mounts have 180,000 miles on them and they're still in fine shape. If the OEM replacements are cheaper, I'd go with them.

 

I this these as well. ^^^^^ Andy's good people.

These mounts are well made, and tightened up the engine nicely. The stock mounts are garbage IMO. This is my second XJ with poly mounts. I learned the hard way on my forst XJ.....broke 2 of them, covered under warranty, then had enough and got poly ones.

I do not off-road or beat on my XJ.......just crappy OE mounts.

Now, you will get more vibes through the car, but remember, this isn't a Lexus or Caddy......if you want to feel zero vibes, an XJ is not a wise choice in vehicles.