Help diagnose transfer/transmission sound (1 Viewer)

[Noveske]

Hi everyone,
Hoping to get some ideas on what may be causing this grinding noise which seems to be coming from the transfer case area. The truck is a 1979 BJ40 with a 4 speed transmission. The noise occurs in all 4 forward gears (while moving) and does not occur in reverse. When the clutch is released (up position) the noise persists. The transmission and clutch feel normal. It started to occur after changing the transfer case oil to amsoil 75/90. (Trans oil was also changed) the lockers have always been off and the truck is in 2H. The truck was only driven around the block after the fluids were changed when the noise began. Fluid levels are ok.



Noise from inside while moving:


Thanks!

 

[mrldcty]

If I were to guess "cold" (i.e., without assuming it's coming from the trans/tc), it sounds like a loose fan shroud hitting the fan. Did you touch anything up front?

 

[igotta40]

That sounds like a gear is only partially engaged, Check the shifter movement.

 

[ijonesinsp]

Do you hear anything with the clutch out and coasting in neutral?

 

[45Dougal]

Is the PTO fully disengaged?

 

[Noveske]

If I were to guess "cold" (i.e., without assuming it's coming from the trans/tc), it sounds like a loose fan shroud hitting the fan. Did you touch anything up front?

Thanks, nothing up front and the fan clears without any issues

 

[Noveske]

Do you hear anything with the clutch out and coasting in neutral?

 

[Noveske]

The noise starts as soon as the clutch is about 80% let out and the car begins to roll. When I press the clutch back in, the noise continues as the car rolls.

 

[Noveske]

Is the PTO fully disengaged?

I don't think this has a PTO?

 

[Skreddy]

It definitely sounds like something spinning is hitting something else. Look where you last touched: changing oil. So, any chance skid plate or anything else was removed and when reinstalled the driveline is rubbing on it or? Knobs on tire hitting something? Sounds too “external” if that makes sense. (Fan hitting shroud was my first guess like @mrldcty suggested).

 

[Noveske]

That sounds like a gear is only partially engaged, Check the shifter movement.

Shifter feels normal, even with firm shifts the noise is still there

 

[Skreddy]

Have you tried locking and unlocking the hubs as well as shifting in and out of 4wd?

 

[WildernessRimFab]

It definitely sounds like something spinning is hitting something else.

Im with @Skreddy thats spinning metal on metal and it sounds horrible. Do not drive at all until you figure this out.
Another suggestion would be to get under the truck and make sure that the transfer case is all the way in 2H. Xfer shifter slop can be deceiving.
Have someone move the Xfer shifter around while you are under the truck and youll see which shift rods are supposed to be in/out for 2H.
Note that there are 2 places where shift rods enter the Xfer case, one for High-Nuetral-Low and one for 2wd/4wd.

 

[45Dougal]

I don't think this has a PTO?

It normally hangs on the left side of the transfer casing if you have one (looking forwards).

Otherwise maybe something got pulled against one of the prop shafts?

 

[Noveske]

Im with @Skreddy thats spinning metal on metal and it sounds horrible. Do not drive at all until you figure this out.
Another suggestion would be to get under the truck and make sure that the transfer case is all the way in 2H. Xfer shifter slop can be deceiving.
Have someone move the Xfer shifter around while you are under the truck and youll see which shift rods are supposed to be in/out for 2H.
Note that there are 2 places where shift rods enter the Xfer case, one for High-Nuetral-Low and one for 2wd/4wd.

Thanks! I inspected this morning- the 2/4 movement is solid but there is a lot of looseness and slip in the low/high linkage. (Right and left movement on the knob) Is there a possibility that the sound is a result of not fully engaging low or high? Stuck in between?

 

[WildernessRimFab]

Thanks! I inspected this morning- the 2/4 movement is solid but there is a lot of looseness and slip in the low/high linkage. (Right and left movement on the knob) Is there a possibility that the sound is a result of not fully engaging low or high? Stuck in between?

I would focus on the position of the H/N/L shift rod exiting the xfer case. High range would either be all the way in or all the way out (I don't remember which), but this would be easy to tell lying under the truck while someone works the shifter.

 

[peesalot]

Sounds like the 4wd collar is not fully shifting into 2wd or you say you changed tcase fluid, what did you use for the drain plug and did you put the washer on it ? reason, if you used a non stock plug or deleted the washer ( which is a comp ring) the plug could be hitting the gear in tcase, it is very close.
This would be my best guess. FWIW 90wt in the tcase.

 

[Noveske]

Update- with the car off, transfer in neutral and trans in neutral, I was able to reproduce te sound just by pushing the car. It seems to be a loud chattering coming from the parking break disk that is next to the transfer case. Any ideas? Thanks to all

 

[peesalot]

You may be lucky and have just too tight barely e-brake shoes. Try adjusting off 1 click and see if noise goes away, I will say that sound was more teeth contact sound than shoe drag but I have had my ebrake just barely drag and it makes wierd sounds. Search on here for which direction to rotate adjuster to back shoes off and to find adjuster if you dont know where it is. Its on the backing plate for e-barke, at the bottom.

 

[77mustard40]

Is the rear DS contacting the skid plate by chance?