knocking when climbing steep hills

[Shomsky462]

ok take out the 20 pound sledge hammer sit in your jeep and bang on the frame thats the kind of sound it makes

 

[WesternXJ]

To check the motor mount. Get another set of eyes or pop the hood and get in the drivers seat and look under the hood and above the cowl, so you can see the valve cover. Start the Jeep, put it in gear and keep you foot on the brake and apply some throttle (power braking). If the valve cover moves dramaticaly, you have a broken motor mount.
HTH
:wave:

 

[Goatman]

ok take out the 20 pound sledge hammer sit in your jeep and bang on the frame thats the kind of sound it makes

That sounds like a motor mount. If it's banging that loudly it should be easy to see that the motor mount is bad just by looking at it. The rubber will be cracked and even partially gone.

Back up from the computer, go out to the Jeep, pop the hood, and take a look.

 

[Superhonky74]

I have an 87 XJ and get the same response. I noticed that the front shaft was on the exhuast pipe?????Check for rub marks on your exhuast pipe.

 

[DaffyXJ]

ok take out the 20 pound sledge hammer sit in your jeep and bang on the frame thats the kind of sound it makes

I liked what Goatman said. Is it consistant with wheel speed, RPM, or just a random noise? The sledge sound, if not engine mounts, could be the track bar frame side bracket. When loosened, they make quite a racket.
I have a ratcheting sound (consistant with RPMs) from the XJ when going up hill. Thought this might be the type of noise you where refering to.
I went through the front just today with no joy. Back lash is good, Pinion preload good, all the ring gear/pinion teeth still there, front drive shaft okay. So my issue is probably the T-case chain slap. But might look at motor mounts also.
If it's loud like a hammer hitting metal, check the track bar frame side bracket.

 

[Shomsky462]

yeah i cant really check the motor mounts right now because my jeep wont start. i have a new solenoid that im going to put in it and i need a new alternator. havent had a chance because i kinda have the flu and my head hurts really bad and have like zero energy. but yeah what is the advantage/disadventage of the 1 inch rise motor mounts? whats the difference between just stock?

 

[stupidfast]

It is VERY hard to diagnose a noise with as vague a description as we have here.

yeah it was a while ago that i checked it. the interior is stripped now and i cant (comfortably) drive it. ill check it some other time

 

[T&A-XJ]

1" raised motor mounts is a no go in an XJ

 

[Goatman]

I liked what Goatman said. Is it consistant with wheel speed, RPM, or just a random noise? The sledge sound, if not engine mounts, could be the track bar frame side bracket. When loosened, they make quite a racket.
I have a ratcheting sound (consistant with RPMs) from the XJ when going up hill. Thought this might be the type of noise you where refering to.
I went through the front just today with no joy. Back lash is good, Pinion preload good, all the ring gear/pinion teeth still there, front drive shaft okay. So my issue is probably the T-case chain slap. But might look at motor mounts also.
If it's loud like a hammer hitting metal, check the track bar frame side bracket.

You can't tell if the double carden joint is bad by anything other than knowing what noise it makes or taking it apart and inspecting it. You cannot diagnose it by shaking the driveshaft. If you have a ticking sound while going up hill only in 4wd that is much faster than the wheel speed you need to pull the drive shaft and check the double carden joint. The most consistant load on the front shaft is going up a hill, most obstacles don't load the front shaft long enough to hear the noise of a bad u-joint in the carden joint.

A track bar brace noise doesn't happen under load, it happens when you turn or when the front suspension cycles. A t-case chain can be a low volume scraping noise that you could hear in 2wd, or I guess a slaping noise in 4wd but I've never heard it do that. If the chain is worn enough to skip it will pop loudly, and usually one pop at a time.

Again, you should be able to see a bad motor mount just by looking at it if it's bad enough to cause a bang.

 

[ks92xj]

I had the same noise. It was my disconected sway bar.

 

[hotrod22]

I have the same noise when climbing a hill, it is the muffler(stock) hitting the rear pinion yoke under the flex or squat while climbing.

 

[xjbubba]

I experienced the same "hammering" moons ago, while climbing bumpy stuff. Turned out to be motor mounts. Separated mounts allowed the front u-joint to hit the exhaust down pipe.

 

[leftyatm]

Hey now what kind of grade is this hill your wheeling on. in other words how steep is it and what kind of angle is your rig sitting at. it could be that its your motor knocking when the oil surges to the rear of the sump making it hard for all those tiny intricate parts to get that precious fluid (oil.) You can either try adding more oil which may help when it surges to the rear of the pan (sump) or you could try staying off the big hills until you totally find out what it is.

 

[Ghostrider]

It could be the front D/S- But it could also be the driveshaft knocking against your exhaust. It seems to be fairly common. Crawl under and look closely- You need at least an inch between the driveshaft and the exhaust. You may also have a shiny patch on teh D/S where the shaft was rubbign aginst the pipe, or a pipe with a dent in it. I had this probelm after I had the exhaust done. First time I went out, pulled the QDs and ran into a "frametwister" there was this knocking that started up. If you don't do anything it may eventually "self crearance" but why wait? HTH

Ghostrider

 

[Shomsky462]

ok yeah ill check out everything you guys are talking about. thanks a lot for the help!!

 

[MDMIKE]

When you get it running again, put it in gear and do a "brake stand" (I.E. one foot on the brakes, one on the gas). If the motor looks like it wants to come out for a visit, the motor mount/mounts are shot. Good luck man!

MIke

 

[Shomsky462]

ok thanx ill do that then do a brake stand. ill prolly need new motor mounts

 

[PhoenixTX]

Hopefully the original poster gets his issue fixed. Just wanted to say thanks for the replies to this thread. Since I had been told that it was nothing to worry about, I had ignored it. After reading the advice in here... checked my motor mounts and sure enough the driver side mount is missing half of it's rubber. Power braking it results in the motor lifting about a 1.5" and a nice clunk sound... just like I was hearing on climbs. Will be ordering some motor mounts today