Transfer Case or Rear Diff Gone?
 

Hey guys,

So basically what happened was last night I was driving along the highway in 6th gear, heard some whining but wasn't sure whether it was coming from the back or the front.
I got off the highway at an off ramp and when I pressed my clutch in the car pretty much locked up (felt like it was the rear wheels), there was some clunking noise when I had to move my car into the emergency/breakdown lane. Ended up getting it towed home.

I only just got the car back for about 3 days after getting the clutch changed and the mechanic did mention he changed the transmission and transfer case fluids (gonna call them up tomorrow to confirm what oil they used).

I jacked up my rear end today because I thought it was my rear diff that blew, the rear wheels spin freely but when I try the spin the tailshaft it doesn't budge. Drained the diff oil and there were no metal chunks that came out or even shavings stuck on the magnet plug. The oil came out kind of dark green/grey.

My question is since no metal chunks came out from the rear diff, is it the transfer case that's gone? Also if my mechanic used the wrong oil, would it cause immediate damage in the transfer case? There was no whining when I was driving it for the 2 days before and it only just started whining when I was cruising on the highway.

I'll be draining the transfer case fluids tomorrow to check. I did do a search for consequences of a bad transfer case but nothing comes up about the rear wheels locking up.
Everyone says the car will lock up but did not mention whether it'll be all 4 wheels or front or rear..

Had a similar situation happen to me a few years ago. Same thing happened to me, as soon as I pressed the clutch the car locked what seemed like all four wheels, hard to tell because it all happened so quick and unexpected.

What was found was a broken 5th gear fork, which cause the failure.

So transmission may be something to consider here. Mine overheated and was low on oil causing this.

Before you drain the transfer case, remove the FILL plug. Fluid should run out. If it doesn't, the transfer case is likely under filled. Take it back to the shop that just did the work.

Have them drain the tcase into a measuring container with you watching. They get .6L out of it.

Hmm the gears seemed to go in smooth during the days I drove it before the lock up, how would I test each gear?
I'm kinda too scared to drive it but when I drove it to move the car across the road, the car seemed to drive fine but I was in 1st gear going at like 10km/h.

The issue is I don't know if I'll be able to drive the car to the work shop without it locking up again and if it is the transfer case, I don't want to risk damaging the drivetrain.

I know everyone recommends 75w90 for the transfer case, if they filled up with the incorrect oil would it cause any immediate damage?

Only if they used a GL4 (manual trans) oil instead of the required GL5 (hypoid differential) oil.

So I took it to a shop that specialises in evos today, and turns out it wasn't the rear diff.

We hoisted the car up was going to drain the transfer case but guess what happened when we undid the drain plug? Nothing came out, the mechanic that changed my clutch, drained the fluid but didn't top it back up.

Very surprised it lasted that long with no fluid in it..

Yeah me too! My guess is the mechanic drained probably like 300mL out and because the past few days I had it I drove it fairly nicely, and for short distances I guess there was no real 'heat'.

Maybe it was only when I got on the highway giving it a hit at like 5k+ rpm when the heat really built up and burnt off the remaining oil.

When the workshop took off the inspection plate, it smelt pretty burnt.

Bought a secondhand transfer case and was able to drive it out the same day.
I'll be sure to never take it to the shop that did my clutch again. It was one expensive lesson learnt.

Well, if some fluid came out of it, it is VERY easy to underfill the transfer case. Most mechanics will stop filling a differential once fluid comes out the fill plug. On the evo tcase this starts to happen when it is less than half full due to the design. So if it was 300mL short, he likely simply underfilled it. They tcase only holds 600mL.