transmission frustrations: NV4500/AA/split case

[cody c]

Ive had a leak for a while now and Im trying to locate the problem.

I have the Advanced Adapter between the NV4500(cummins) and the 60 series split case, the thing has been leaking more and more for the past couple months and I really need to get to the bottom of it.

My trans is just about out of fluid. There is oil on top of the transmission and the split case is soaked and dripping.

The split case is soaked but has plenty of fluid in it, the breather on it is also pretty much clean and not leaking.

The top of the transmission is oily around the top and near the breather, but there is no noticable source for the leakage.

Im thinking I either am somehow blowing oil out of the breather on the trans, or am pushing oil to the t-case and then its seeping.

At around $30/litre of the special transmission fluid for the NV4500 (uses about 4 litres and must be made of koala tears for the cost) filling it up every now and then is not really an option, driving it without fluid probably isnt either.

I've separated the transmission from the motor a few times too many in the past, and the t-case from the trans to try and solve a slowly developing leak (by using heaps of gasket maker in between everything) which seemed to make it go away, but loathe the idea of doing it again and not really knowing the source.

Any thoughts on an upgraded breather to avoid possible leakage? I kinda got a feeling it is just pushing the fluid forward to the split case, and for what I payed for the adaptor (about $1K CAD to the door) Im gonna be on the phone with AA to tell them how I feel if that is the case. (I wonder if I could put dye in the trans fluid to see if it migrates to the t-case? Also, any thoughts on clear tubing and two ports on the t-case to check fluid levels?

Any help or distraction much appreciated.

 

[terrx]

It needs a good sealant with that synthetic oil. Do you know what it has now? Anaerobic vs. RTV (ultra grey/black)?

 

[Tigerstripe40]

Also, any thoughts on clear tubing and two ports on the t-case to check fluid levels?

Any help or distraction much appreciated.

For trying to find the problem, that may be a solution. I would probably get new drain plugs for the transmission and t-case, drill some holes in the old ones, thread in some pipe fittings and then attatch some clear tubing to be able to more easily check the levels.

But, I wouldn't do such a thing as a long term solution. My concern there would be that the clear tubing could potentially get snagged on something and then rip out, causing all of your gear lube to come out of the transmission or t-case.

 

[EWheeler]

I know FJ40s have an situation where the transmission pushes fluid into the transfer case, overfilling the transfer case and causing some leaks. I have seen solutions where people with take out the fill plug of both, and put a connector tube between the two fill holes (using properly sized/threaded fittings & adapters). Depending on the difference in height between the two fill plugs this could be an option. If the fill plug on the tranny is much higher than the fill plug on the transfer case, this probably wouldn't work.

 

[warpdriv]

You might want to try putting a long hose on the breather of the tranny and mount it on a high place on the firewall to see if it is pushing out the breather. It would just push in the hose.

 

[cody c]

I know FJ40s have an situation where the transmission pushes fluid into the transfer case, overfilling the transfer case and causing some leaks. I have seen solutions where people with take out the fill plug of both, and put a connector tube between the two fill holes (using properly sized/threaded fittings & adapters). Depending on the difference in height between the two fill plugs this could be an option. If the fill plug on the tranny is much higher than the fill plug on the transfer case, this probably wouldn't work.

I cant do this (I think) because the transmission uses a special and different fluid, which is expensive and designed specifically for the carbon fiber syncros, apparently regular transmission oils will cause the syncros to come apart.

You might want to try putting a long hose on the breather of the tranny and mount it on a high place on the firewall to see if it is pushing out the breather. It would just push in the hose.

I think I will relocate the diff breather, make it higher and so it acts like a bit of a "catch-can" if the transmission is throwing any fluid at it, then later it should gravity feed back in, and maybe just run the line to a "T" to support breathing of diffs and drivetrain and plumb it all the way to the air can so it shouldnt take any water in if im going through a creek crossing, and will vent lubricant fumes into the engine to be combusted.

Ive also got a CAT catalogue number for a dye I can add to the fluid to see if it is migrating to the t-case through the advanced adaptor, though it will be a while before I have time to go and grab some and add it.

 

[cody c]

For trying to find the problem, that may be a solution. I would probably get new drain plugs for the transmission and t-case, drill some holes in the old ones, thread in some pipe fittings and then attatch some clear tubing to be able to more easily check the levels.

But, I wouldn't do such a thing as a long term solution. My concern there would be that the clear tubing could potentially get snagged on something and then rip out, causing all of your gear lube to come out of the transmission or t-case.

There is mo drain plug on the transmission believe it or not. I may be able to use the PTO cover, pull it, drill and tap it, then install a 90 degree fitting to a barbed "T" and then try and find a higher spot, but it could involve drilling and tapping the case, as the fill plug is has an allen head socket instead of a hexagonal style bolt head, as such I dont think I could drill and tap it without wrecking the walls of the allen head...

Im not worried about the t-case, its still full, and I installed an "air compressor" style drain butterfly valve where the fill plug is, which I can just turn a little ways and see if fluid comes out. Takes about 2 seconds to check and I dont need any tools.

I may look at installing the tubing on the trans though, it could save me from having to replace the transmission at some point, I do see your point at protecting the line from damage. Aside from mechanical protection, a small valve at the bottom side of the tubing should help for that though.

 

[spotcruiser]

If you have the removable shift tower, check to see if it's leaking where the shift tower mates to the top cover. There is a spacer there, with one side rubber and the other side metal. The rubber side seals well, but the metal side not so much. Try sealing the metal-to-metal spacer contact surface with RTV.

 

[cody c]

If you have the removable shift tower, check to see if it's leaking where the shift tower mates to the top cover. There is a spacer there, with one side rubber and the other side metal. The rubber side seals well, but the metal side not so much. Try sealing the metal-to-metal spacer contact surface with RTV.

Never thought to look there, thanks I will check that as well!

 

[CRZR45]

My NV4500 in my 4bt/NV4500/Orion 80 series had the same unknown leak when it was first built.. My drive train is bone dry once I sealed the top plate with sealer on bothsides.