85 Rear diff nasty "ping..Ping" sound... any ideas?

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S

Schroder

10 Year 15 Year
Joined
Nov 26, 2006
Threads
6
Messages
43
Location
Denver
I am normally over on the 80 series criser page, as I have had Zero issues with my 85 PU. The other day, it starts to make a pinging sound. It gets louder over time in just one day of normal street drivning.

WHEN: during deceleration. You can accelerate, gear engaged, no noise. You go to shift gears, or simply coast, and it starts right away.

DIAGNOSIS: Had the wife drive while I layed sidways out the pass side door w/ my head under the truck (just 1st gear...), and it is clearly coming from the rear diff general area. When there is load put on the rear end during accelleration, the rear axle and diff rotate up a little. No noise when in that position. When the axel relaxes back to a low or no load position is when the noise starts. The noise gets faster the faster you go, and as you go slower, it goes slower, no matter if you are in gear or not. Ughhh. It is a Ping...ping ...ping... I checked fluid level, all is well, and I dont leak from back there at all.
The rear drive shaft has about 1/4 to 1/2 inch of play back and forth if you get under and roll it side to side. There is some light weeping (and knashing of teeth) of what appears to be oil right where the rear driveshaft connects to the part that goes into the rear diff (I know, horribly technical).

TRUCK: 250,000 miles on the truck, 150K on the motor, transfer case and transmission, swap was done 2 years and 20K miles ago. Just re-built front axel/birfields less than 1000 miles ago. New shocks all around.

Looking for help on this one. Thought it was U-Joint (Spider Joint in the FSM), but it shows no sign of any movement when you do the "drive shaft play" test.
 
I bet it is your ujoint. Unless it is super shot it will pass the wiggle test. Remove the rear drive shaft and drive it in front wheel drive. If the noise is no longer there it is the ujoint. If you still hear the noise it is time to pull the rear diff.
 
Thanks for the tip on testing it. I will try that tonight, and reply. You recommend OEM Toyota U-Joints? or does it matter?
 
Schroder said:
Thanks for the tip on testing it. I will try that tonight, and reply. You recommend OEM Toyota U-Joints? or does it matter?
Click to expand...
Howdy! Yes, I recommend OEM. Tolerances on cheap U-joints are not very accurate. BTDT. Do the joint, as it is probably overdue if it is original. You can pop the caps on the old one, and it is going to be ugly in there!! Cheap and easy compared to opening up the rear diff. JOhn
 
Ok, picked up the joit at local Toyota dealer (would have used Cruser Dan, but needed it to install tomorrow). Trick now is the fact that I have to do the PHH on my Cruiser tonight first, then worry about doin the truck. I will follow up on this posting.
 
So what about doing the 2 in the front? My thought is to put a grease gun to them, and see how long they last, as the rear end would get much more wear than the front (unlike the cruiser, where it is full time 4WD.). Thoughts?
 
Sweet. Thanks. I will let you know. I have the rear drive shaft out. Now when I put it in 4WD, and drive only using the FWD, there are new noises. I think it still may be the timing chain slapping though. Gotta figure out that one too.
:confused:
 
So, rear diff is back in, with Toyota U-Joints properly installed. Rear noise is now gone. Front is worse. I will try the "motor -off , glide in Neutral" test. Great idea, not sure why that did not occurr to me to eliminate the engine noise to issolate the possibility of it being mechanical drive train while it is still moving. Hmmm.

So I take it the front drive shaft rotates all the time, which would only make sense. Granted, it is not engaged under the kind of load it would be in 4WD (say like my full time FJZ80 is), but wear at 250K is still likely, given that I know the PO did not do them (had it from 133K through 233K when the HG blew), and I have no history on the owner who had it befor the PO.

BTW, good call on the Toyota U-joints. So, having looked up front, looks like there are 3 up front! Time to call Cruser Dan for the discount.

Thanks for the tip, will keep posting progress.
 
Hmm, Uh, well, I did your test going 65 on the highway. When the truck is cold, no noise. When it gets to normal operating temp, the noise is back. So, i did the test on the highway on the way home from work. 55, noise there, and shut the truck off, let it coast in Neutral. Sure enough, noise still there. Even after 1 mile, truck is going 50 now, and the noise is still there. Start the truck, engage back into 4th, and noise is nice and loud. Try it again, same result.

So, after I read your reply, I am feeling plenty stupid, as I left the hubs locked after changing the rear drive shaft, and doing the front wheel drive test. I pulled it out of 4WD, but did not unlock the hubs. So, in some ways, it is a good thing, as I have definitely issolated the issue.

Also, I know that the PO (ok, it was my dad), who knows nothing about 4WD's, left the hubs engaged for months at a time. He used the truck for courier work, and put 100,000 on that thing in 2.5 years. So, for as long as those hubs were likely locked, it is amazing they didn't go a long time ago. Now I am putting some decent stress on them wheeling the truck, and they are shot. The noise is incramentally worse since I started this thread.

I have a call in to C-Dan, parts will be on their way to my humble abode by COB tomorrow. I will post the results.
 
So according to C-Dan, there is only one U-Joint that is serviceable on the front propeller shaft. The other two make up a constant velocity joint that is not serviceable. So, I am taking the drive shaft off this evening, and will check the parts out.

Either way, I ordered the U-joint, as even if it is broken and I pick up another used shaft with the CV Joint in good shape (Yoda Man, $75), I will still put in a new U-joint with the front drive shaft already off of the truck.

BTW, if you all have not found this guy here locally in the Denver area, he is all toyota 4 runners & Trucks. No cruisers or anything else, small yard, very fair prices for used stuff. I will post his info if anyone is interested.
 
So, front U-joint is in. Drive shaft back in. Road tested, all is well. Changed the rear diff fluid, transfer case fluid, and motor oil while I was waiting for the part to come in. (BTW, thank you again, C-Dan. Your prices never cease to amaze me!!) The truck even got detailed (as much as you can detail this truck anyway, meaning it got cleaned up a bit).

Since I had the truck in the garage, it was time to put in another amp and some additional door speakers. The amp was easy, the speakers are another story. What a PITA. Ther is really not much room in those doors, and the window slider pretty much soaks up any available square inch that is left. I put in 5.25" speakers, and had to do some fairly significant cutting. Anyway, they are in, and in addition to the tiny ones in the dash pannel, the system sounds much better now. At least I can turn up the radio and hear it over the road noise at 60+MPH.
 
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