I just finished my auto to nv4500 swap about a month ago and have about 1700 miles on the swap. I was driving down the highway yeasterday and stopped at a gas station about 25 miles up the road and while filling up my truck noticed there was a puddle of fluid building up under my truck. After further inspection the NV4500 was puking the very expensive Syntorq gear oil out of the breather hose. The transmission was also hot (could only touch the trans for a second or 2). Is the dealership Syntorq known to foam up? I put 5 quarts of the stuff in the trans so I don't believe i overfilled it. I am considering putting something like Geno's garage Fast Coolers on the trans to dissipate some heat. Maybe the bearings are getting too hot? Any suggestions on fixing this before it becomes a much more expensive problem?

 

Not sure how it works like this, maybe output seal is bad? Have you checked transfer case fluid? It is ATF vs. Syntorq, might foam and overflow if they are mixing. Does it rattle real bad or anything? How many miles on the NV4500? If it was empty, should not be that hot after 25 miles.

PS just thought of this. I remember when doing my swap, there was a plug inside the shaft (I think?) I had to transfer from the old input to the new of transfer case. Seemed kinda fussy as to perfect positioning. Did you encounter anything like this? Maybe it didn't seat right. Just thinking out loud.

 

i replaced all the seals on both the trans and tcase. all the fluid coming out of the trans is clear gear oil without any atf. I was told the trans had about 140K on it. It does not rattle at all and shifts and drives great. as far as a plug i am not sure i dont remember one?

 

Not overfilled? I always used Mopar® Synthetic Manual Transmission Lubricant 75W-85 never had a problem.

 

no not overfilled

 

Any luck on finding out whats up?
The tranny shifted really smooth, with no leaks before I pulled it for you.

 

the trans holds 4.25 quarts i had it at 5 so Im guessing it is overfilled?

 

Just curious my factory service manual say fill to bottom of fill plug, that was 4 quarts for me?

 

One school of thought I hear all too often is to overfill the tranny from the top by removing the shift lever.
Very bad idea, more isn't better.
Much engineering went into the correct lube level, the bottom of the fill hole.
Most any tranny, gearbox, etc that is overfilled will run much hotter thus expanding the fluid causing it to puke.

 

Sounds like your good to go then.
I do hear a lot of people say that overfilling the Getrag by one QT is a good idea.
The NV-4500 doesn't agree with this treatment I guess

 

Precisely. I overfilled my Getrag to keep the input bearing lubed. But my NV gets only whats recommended.

 

I just threw 5 qts in and haven't had any problems, even towing in 5th. About 10k on the swap now, only new parts are main/counter and input bearings. Maybe worn bearings adding to the heat...? Mine was just a little too warm to touch after a good run with the trailer, about 7500#.