93 FZJ80 Metallic CLANK from park to reverse/drive (1 Viewer)

[1Yota]

I have gone through the gammit of clank/clunk/grinding noise posts and I may have a new one.......but hopefully I just missed it and someone can point me in the right direction??

This is a 93 FZJ80 stock engine and auto trans, runs and drives good, with a clanking periodically (doesn't match any specific rotation) and it will go away for five miles and then be back. I can't hear it at highway speeds, but that's probably because this land tank is freakin loud! haha If I only heard the rattle and not the "metallic clank" I wouldn't even bother to look for anything......

Now, the root of the noise is most evident when I shift from park to drive or reverse, it sounds like a lawn gnome hitting my driveshaft once with a ball-peen hammer. Then as I start to drive, I get the on and off noise of a rock in a tin can and the occasional ping/clank of that ball-peen hammer.

Additionally, I noticed that when the truck is in park, I can push the truck in either direction maybe two inches and then it's actually "locked" into park(you can here it click and can no longer move the truck).....When I push it back and it "locks" into park, if I then put it back in gear, I don't get the clank....but it will return when driving with mostly just the annoying metallic rattle. (is the the transmission parking pawl not engaging)

Basically, for troubleshooting I have verified all the fluids, lubed driveshafts and u-joints and checked drain plug on TC for metal....nothing.

I think these are the basic symptoms, I'd really love to not tear apart the TC but I swear the noise is coming from the rear side of it???

For Some reason I am unable to post a video, I will try and figure that out.....

Cheers!

 

[Fj80oregon]

Check you exhaust hanger by the t case. That’s what my clank was the drive shaft would touch the exhaust for just a second or two because the rubber isolators where separated.

 

[Fj80oregon]

If you lift up your exhaust right behind the muffler if it lifts up that might be the culprit there 3 I believe in the whole system.

 

[mudgudgeon]

Does it clank when you take your foot off the gas, or when you put your foot back on the gas?

Have you checked front hubs and drive flange/birfs for worn out splines?
Pre '94 were prone to wearing out drive flange and Birfield splines. This cause a driveline clunk.

lubed driveshafts and u-joints

Did uni joints get inspected? Or just lubed?
I find, it's hard to assess the uni joints without unbolting driveshafts.

 

[CharlieS]

I also had a clunk related to universal joints failing on the rear shaft. It was a very noticeable "clunk" that almost felt like driveline lash. At the end, it was easily felt by rotating the driveshaft by hand - but only when in neutral (wheels chocked).

Hahaha - a gnome with a ball peen - love it. I like the rubber mount theory. Check the exhaust mounts, transmission mount, motor mounts. (in that order). I also had broken exhaust mounts that led to similar noises, but I also had a transmission mount where the rubber part was fully detached from the metal part. These allow movement that can cause the gnome to pull out the ball peen.

 

[Francis K]

Does it clank when you take your foot off the gas, or when you put your foot back on the gas?

Have you checked front hubs and drive flange/birfs for worn out splines?
Pre '94 were prone to wearing out drive flange and Birfield splines. This cause a driveline clunk.


Did uni joints get inspected? Or just lubed?
I find, it's hard to assess the uni joints without unbolting driveshafts.

Mudgud what is it indicative of when it clanks when you put your foot back on the gas in addition to putting in gear?

 

[mudgudgeon]

Mudgud what is it indicative of when it clanks when you put your foot back on the gas in addition to putting in gear?

If it clunks, clanks, thunks as you rock on/off the gas while driving, it's slop in the driveline.

There will always be a little bit of play in diffs, transfer case diff, uni joints, slip yolks, and birf/flange joint at the hubs.

If it's excessive, it's a high chance it's the splines worn out on the birfs and in the drive flange. Especially pre '94.

Uni joints would be my next suspect.

But excess wear in any connection point above will contribute.

 

[1Yota]

Does it clank when you take your foot off the gas, or when you put your foot back on the gas?

Have you checked front hubs and drive flange/birfs for worn out splines?
Pre '94 were prone to wearing out drive flange and Birfield splines. This cause a driveline clunk.


Did uni joints get inspected? Or just lubed?
I find, it's hard to assess the uni joints without unbolting driveshafts.

I took the rear driveshaft off to check the splines, u-joints were in good shape.

I resealed the front axel/hubs about 6 months ago and the drive flanges were solid.....hopefully they didn't crap out in that amount of time!?

The clank is when I first put in in gear and sometimes when I first start moving, but while driving, being on the gas vs coasting doesn't seem to make a difference.

I will take a look at the exhaust again, but I was under the truck while it was shifted into gear and I didn't actually see anything hitting....

The driveshaft "jolts or jerks" a little when its put in gear which i would expect, that jolt motion matches the noise if that helps.

I feel like I'm decent at figuring out a noise usually