I got an 03 3500 SRW recently with 127k miles on it. H.O. Cummins with the NV5600. Everything looked clean with it besides a bit of rust behind panels, nothing major for me and frame is in good shape. I didn't notice any leaks when I bought it.

So I get it home and I notice a leak the next morning. About the size of a softball. Found it odd but had to leave. Never saw any drips when I parked it anywhere else. Backed UP into my driveway again and the leak comes back. For experimental reasons I turned it around and pulled UP into the driveway. No more leak. I backed it in today and by the time I got the hood popped and tire chocks in place to crawl under it, a puddle almost the size of a golf ball had formed. Looks to me like it's coming from around the bell housing so I would guess the front main seal for the trans. Anyone have another idea? If that is the case, I guess I'll be pulling this heavy monster soon to replace it. Might as well put a good clutch in it while I'm in there. I know I can't keep driving it like this, I've read the rear seal has a hard enough time getting fluid when it's full, much less when it's leaked this much out over time.

Wondered if anyone else ever had this experience of only leaking when facing downhill and maybe there's something I'm just not thinking of. I really don't look forward to pulling it but ya know.... ya do what ya gotta do.

 

Check the fluid level first. I can't recall EVER seeing a trans leak fluid out the front. (at least, not a manual trans.....) It may just be overfilled.. (hopefully, it's that easy.....)

 

Guess it's possible. These take 4.75 quarts according to my research but most people actually put 6 in them to help bathe the rear seal and they don't have leaks so it would probably have to be way over full to leak, but you never know when you buy a used truck.... hard part is finding a level spot near me to check it. It doesn't fit in my garage haha

 

Over filled or maybe a plugged vent???? No clue where the vent actually is on those though.....

 

Also possible. And I also don't know where but I can find it I'm sure. Just a really weird way to have a leak

 

I'll give ya that one.

 

Fluid is not over full. Needs replacing, it's dark. But I can clearly see it coming down and out the gap where the bell housing meets up with the "adapter". I don't know the technical name of that part, but it's where the starter bolts in, which I know on a normal transmission would be the bell housing, but there's an extra part on this one for some reason between the block and the bell housing. So... I don't know. I guess it's the trans input shaft seal. Don't know how it's leaking with such low mileage but I guess it is

 

Well that sucks. Guess you know what ya gotta do then. Sorry man.

 

All good! Gonna limp it until it needs a clutch if I can get it to hold enough fluid. If I can't, I guess I'll replace both soon enough! Haha

 

Coming from a guy who has an NV5600, you should overfill the trans by a quart. Yes, it helps lube the rear seal but the main reason is it cools/lubes 6th gear better leading to less chance of premature failure. I also put fast transmission coolers over the pto covers and added a trans temp sensor to mine because i do tow a lot in the summer. I think with the coolers added, I added 2 extra quarts to equal the 1 extra quart without the coolers.