Transfer Case vs Differential

2016 4runner Limited.

I took my 4Runner into the shop for a loud heavy metal clunking sound, seemingly coming from underneath, just aft of the engine. It happened whenever I was demanding more torque, i.e. starting from a stop or slow speed going up an inclined driveway. It continued clunking as long as I was demanding high torque and accelerating. The symptom happened in drive, and reverse. Once I'm at speed and just maintaining speed, it doesn't happen any more.
The dealership said it was the differential, and replaced that, but it didn't fix it. They said it helped, but it was still happening. They then put an axle in, and that didn't help at all. They're now saying that the differential had been chipping internally and the metal scrap from that flowed into the transfer case and blew the transfer case.

I'm not an expert by any means, but I thought that those were two separate and sealed cases, each with their own fluid. The owners manual has different call outs for the fluid types, very similar, but why different? Do the front differential and the transfer case share fluid? Or are they trying to cover not needing to do the differential?

 

Dealer is on crack if he thinks a differential part is going to magically appear in the transfer case.

 

The rear diff doesn't flow into the transfer case but since you have a Limited Full Time 4wd, you have a differential in the transfer case. It really sounds like dealership doesn't know what they are doing if they are just throwing parts at it.

 

Have they checked\inspected the driveshaft/yoke. I would assume so based on the repairs they have thrown at it. Has it been lubed regularly?

 

Here's the thing. You have a Limited, probably with a center differential. Many people refer to the transfer case as a center differential, especially a full-time transfer case, because it differentiates power between the front and rear driveline/driveshaft/propeller shaft.

So, they are probably talking about a center differential, not a front or rear differential by which we are used to referring to them.

Also, if you update your location in your profile, it may help people answer questions for you.

ETA: also, the "clunk" may well be driveline related, as someone else stated, related to the "yoke". That is part of the transfer case, or center "differential".

 

OP, what differential did the dealer replace? Front differential or something in the transfer case? Transfer Case is only connected to the front diff with a propeller shaft and there is no way for the front diff and transfer case to swap metal bits.

 

I asked this afternoon and they said they replaced the front differential.

 

They haven't mentioned anything about that, but I'm not sure they would if their inspection didn't find anything. I know that I haven't greased that. I don't know if that's something that gets accomplished by the dealer when I take it in for my routine maintenance. To be honest, I don't even know where that zerk is so my guess is I'm direlect there.

 

This is what I think as well. Also, why in hell they replaced the front when your symptoms described something different.

 

At this point, whatever the problem may be, your current shop attempted to fix it twice without success. I imagine at your significant expense. I would consider that a track record of failure. At this point talk to a service manager and demand they address issue at no labor costs (i.e., you pay only parts) or even better take to a shop that is better at diagnosing issues.

 

Yeesh, you’d think that a purely mechanical issue would not be this mysterious to diagnose.

They’re either pretending to be dumb, or they actually are. In either case, it’s on your dime. Those are some really expensive components to be taking wild-ass guesses on.

Is this a dealer, or independent mechanic?

 

WOW.....sounds like they are clueless! Is this a reputable shop? With description you have given of noise I would be looking at u joints etc.? Bad motor mount? Rear mount causing rubbing? You need different shop.

 

It sure feels like they're just blindly throwing things at it. It's currently at a Toyota dealership. I took it there because it sounded like more serious damage and thought they would be the best option for this.

 

Well if first shop sold you front diff and it had no impact on problem, I would be taking them to small claims court for refund, [I would talk to them first about refund].