So on this '91 I just picked up, I've got a grinding noise at low speeds (that's when I hear it at least). I just noticed tonight that when I shift into 4hi (NP 231) the noise goes away. 4wd is not engaging though, so I don't know what the hell's going on.

I'll also throw in that when I'm stopped at a light in gear, I get a thunking on the floor board (it seems). When I shift into neutral it stops. Any ideas?

Please help I'm getting this thing on the road tomorrow!!!

THANKS!

 

bump, please any ideas?

 

do you have a dust shield on your yoke for the rear, cuz that made a mad grinding noice for me once

 

I don't think so...

It seems to be coming from the front end also.

 

four wheel drive linkage?

 

It's really weird because I would think it'd be the opposite. I don't know whats grinding.

Please anyone have any ideas? This is my daily driver now and I don't want to bust anything on her before I've even gotten a feel for her.

 

drive up and down the street a couple times then get under your jeep and feel around for a lot of heat, i have done this for my civic to see if my cv shaft was rubbing. its a dumb idea i know that but it works LOL

 

Not a bad idea. Where there is metal grinding, there will be heat... I'll try it!

 

remember "were there is smoke there be fire"

 

anybody had the gears turning in the old brains?

 

bump

 

if you have a 231 tc and you put it in 4hi but the front doesnt pull then you front axle is not engaging or you have a problem in the front diff. make sure the vacuum motor on the axle is working. the noise in the floorboard may be a bad trans mount, take a look underneath and make sure its not oil soaked or broken.

 

Thanks Jockey, a broken trans mount definitely is a possibility. Having never really messed around there, what am I looking for? I also vaguely remember reading something about the transmission bolts coming loose or something causing noises on the XJs?

Do you have any tests for the vacuum motor?

I'm still stumped on the reason I'm getting this nasty grinding in 2wd, but in 4hi it goes away. Maybe someone messed with the 4wd vacuum plug and it thinks 2wd is 4? Even possible?

Sorry for my ignorance, I just really haven't messed around with any of the running gear.

Thanks much for your help!

 

the trans mount will be at the back of the trans right where the tc mounts. its what the trans sits on and holds it down to the cross member. if you're leaking oil in that area, it will destroy the mount and believe me you will know it if that be the case. see if you can move the trans tail with your hands or a long bar. if you can then the mount is bad. while your under there take a look at the bell housing bolts, if they are loose you will see were the trans is seperating from the engine. the front axle vacuum motor is default to disengaged. you can pull the accuator off the axle housing (four bolts on back side of axle passenger side) put a vac pump on the port and see if the fork moves. the 231 tc is a manual case. so long as it is not grossly out of adjustment then it is engaged when you pull the handle. otherwise it has internal damage.

 

Okay, thanks. Tomorrow I'll be crawling around to try and figure things out. I'll keep you posted. Just out of curiosity, how bad is it to replace the rear main seal?