BAWC Forums

I would post this on Jeepforum.com, but it would be like going to 3si. If I can't get any help here on this though, I will post over there.

When I start up the XJ I can hear and feel a thud coming from either under the hood or where the tranny is. I can alse feel and hear thuds when I drive down the road.

My first thought was u-joint, so i checked those and they all seem fine. The front drive shaft is a bit loose though, but it has been since I bought it, and that would not make sense to the thud on start up. I then thought maybe it was a motor mount, but when I rev the engine with the hood up, the engine barely moves.

Could this be a tranny mount?

I also ran out of power steering fluid due to a minor leak, but I have since fixed that and the p/s works fine now. All the steering components under the XJ are also nice and tight.

Any suggestions? I don't have the $ to take it to a mechanic right now.

If it help, the XJ is a 98 with the 3.0L I-6, auto tranny, with the NP231.

Somedays it works, somedays it doesn't. People on there are nice, but there are also alot of stupid people there too, and immature.

It is so annoying though since I can feel it against my feet.

Let me preface this by saying I know almost nothing about jeeps...


That said, my father's WJ was having a similar problem after he went off roading. He would get a "thud" everytime he put the car into gear, and you can really hear it if he put it into reverse. Also, we would occassionally hear it when driving down the road, particularly at highway speeds.

He did a bit of research, and thought that it was an exhaust rattle, which is apparently pretty common. I'm guessing he researched it over at jeep forums. To me, the symptoms seemed more like the drivetrain. I hopped under the car and discovered that his aftermarket skit plate was bent up a bit. When he put the car in gear, it would lunge the transfercase down low enough the thump against the skid plate. If you have one of these on your XJ, then it might be worth checking out. (As far as I know, some models of Jeep maybe equiped with OEM skid plates.)

My exhaust really rattles alot, but it is not that. I have the OEM plate, but I was just working on the t-case, and nothing is wrong there.

I might just have to take it to a mechanic and have them charge me out the ass for something small and cheap to fix.

[quote=""Duck Vader""]My exhaust really rattles alot, but it is not that. I have the OEM plate, but I was just working on the t-case, and nothing is wrong there.

I might just have to take it to a mechanic and have them charge me out the ass for something small and cheap to fix.[/quote]

My father's T-case seemed to clear the plate by about .5" when not moving. It didn't seem likely that the Tcase would be the problem, but when the jeep was thrown in gear the load throught the drivetrain would jolt it downwards. It might at least be worth checking. Just have a friend throw the car into gear while you watch from outside.

I will tonight. It just started a few days ago and is getting worse. It sounds under the hood on start up and under my feet/hood when we start moving.

Does it sound/feel the same in both FWD and 4WD?

Haven't tried that yet.

and its RWD, not FWD

[quote=""Duck Vader""]and its RWD, not FWD[/quote]

Hmmm. I could have sworn my Dad said his WJ operated in FWD when in 2WD mode. Is there a difference between the two models? Maybe I'm just totally off base.

I am pretty sure it would be RWD with the V8...my XJ is RWD. Does Jeep even make a FWD vehicle except the new Compass?

[quote=""Duck Vader""]I am pretty sure it would be RWD with the V8...my XJ is RWD. Does Jeep even make a FWD vehicle except the new Compass?[/quote]

His is a V6 Grand Cherokee. I'm sure its the same drivetrain. You're probably right about the xWD.

Most trucks that have an option to switch operate in RWD when not in AWD. I know my Jimmy does, alongside the F150.

[quote=""lawdogg""]No grand cherokees came with a V6 until 2005, I believe. The WK has them, whereas the ZJ and WJ has the I6.[/quote]

I hope this link works...
http://www.cars.com/go/search/detail.js ... f=national

1999 GC, 4.0L I-6 195-hp