My 82 Scrambler is knocking

[jerp33]

Hello I am a very green Jeep newbie. I just purchased an 82 Scrambler. I took it on the hills and when in 4 wheel drive low, I was getting a hard knock when going down hill. I put it in 4H and there was no knock. The knock can be felt in the 4L lever. No knocking on the level or going up hill. If I push and hold the lever forward it seems to supress the knock until I let go of the lever.

Any ideas?

 

[Les]

Hello I am a very green Jeep newbie. I just purchased an 82 Scrambler. I took it on the hills and when in 4 wheel drive low, I was getting a hard knock when going down hill. I put it in 4H and there was no knock. The knock can be felt in the 4L lever. No knocking on the level or going up hill. If I push and hold the lever forward it seems to supress the knock until I let go of the lever.

Any ideas?

Before I got serious about considering that there might be Transfer Case problems, I'd take a close look at both the u-joints, as well as making sure that your Transfer Case is going fully into gear, because unless you have a twin stick, the chances are good that your shifter might be a slight bit out of adjustment and is allowing your Transfer Case to slip partially out of gear.

 

[mtnwhlr]

You might also check your mount.

 

[jerp33]

I checked the Transfer Case and it appeared to be low. I drained it (the magnetic plug had a fair amount of metal shavings, maybe typical the engine was rebuilt 2K ago) I filled the case and took it for a ride and the knocking was reduced 95%. It would still knock once in a while, I would shift out of 4H and then back in and things would be good for a while (20 min) Severe down hill slope seemed to initiate the knocking once again.

 

[jerp33]

I spoke too early, took it for a drive today and it's back to knocking. Down hill only. 4L only.

 

[mtnwhlr]

Did you check your mount? If it is bad you could have your Transmission and Transfer Case bouncing up and down and banging under a load. I asked this before with no response.

 

[jerp33]

How do I go about checking my "mount".

 

[hole]

I would first give all the mounts (engine, Transmission ,Transfer Case ) a visual look-see for the obvious. The way I check for a bad mount is to put the vehicle in low range, chock all wheels, apply parking brake, then raise rpms slightly and ease out the clutch. Having a second person watching from the side looking in the engine bay will confirm which mount has failed. My way probably isnt OSHA approved, but has been effective for me over the years. A little common sense applies here.

Side question; do you hear any clunking when you gas it while in low range?

 

[jerp33]

I will try your mount check directions later this evening when I get home.

As for knockin while "gassing it in 4L" I have not checked it out other than having to give it gas to get up a steep hill. There are a couple of spots on the ranch I am driving on which are pretty challenging in that they are several hundred yard runs where there is alot of slipping and bouncing going on but the rambler gets though it with no "knock". Comming down is another thing, a hard knock every 40 feet or so. Thanks for you input.

 

[Torxhead]

Jerp33, another way to inspect for bad mounts is to look at the clutch bellcrank. It is mounted between the bellhousing and the frame, it also contains the clutch operating rods. It should be perpendicular to the frame, if not, there is a problem. This should indicate sagging mounts causing the motor/Transmission /Transfer Case to lean toward the rear of the Jeep. I have seen this put too much load on the bellcrank mounts and break one of them. Another indicator would be to rev the engine under the hood and watch the engine torque lift it up, even with new rubber mounts it is quite a bit though. That "Banging" could be the Transfer Case hitting the skid plate or the Transfer Case handle hitting the Transmission /Transfer Case cover. There are oem type replacements and urethane types, there are some engine mounts made by M.O.R.E. which are quite expensive and ridgid also. I would also suggest replacing all three mounts anyway.