Transmission leaking, found out why

[M35A2-AZ]

I was going over my truck and pulled off the covers over the transmission and now I know why it is leaking, no vent. I guess when they rebuilt the motor they forgot to put a vent on the transmission. Well sounds good anyway.

 

[spicergear]

Vents, or lack thereof, will do that. When I took the Mog on it's first big trip it was only like 55 miles but an hour and 40 min drived time. When I got home I noticed oil droplets all over the rear of the truck and undercarriage. It was pushing oil out of one of the PTO seals. Ended up finding mud wasps had plugged the tranny vent. Got that cleared and now it's damp around that seal but doesn't drip or make a mess.

 

[Heavysteven]

Typical, My truck was the same way. There was a plug where the vent should have been.

 

[budman67]

Is there a way to put a vent line on,or do you need to drill and tap a new one?

 

[Heavysteven]

Is there a way to put a vent line on,or do you need to drill and tap a new one?

Yes, you could run a vent line. No you do not need to drill and tap. It's NTP i dont remeber the dia though. The spring vent that goes there is the same size that goes on the axles.

 

[budman67]

This is good to know,I am looking to get a M35A2 this summer
economy willing.

 

[M35A2-AZ]

It is 1/8" npt and it is the same as the axles.

 

[Tinwoodsman]

Mine was the same way too. I made many attempt to remove the plug but it was really in there. I ended up changing the tranny out for other reasons so when I address my bad tranny, I will get that plug out.

 

[Vfflang]

Wait a minute ...So that needs a vent ...is there any thing else that needs a vent...I just bought my first deuce drove it home and its was dripping ....thought that was normal but I guess its not a helicopter...

 

[M35A2-AZ]

My PTO seals are linking a little also. Maybe with the vent now all that will stop. Well maybe..

 

[Heavysteven]

The axles, transfer case, and transmission all have spring vents.

 

[ryker725]

I plan on snorkeling all of my vents up into the engine compartment this spring to eliminate the possibility of water intrusion when I take her for a swim. My Samurai mud rigs are like that also..

 

[Flyingvan911]

I am going to replace my vents with tubing too. I will make it so I can pressurize them later on (air switch). I am also going to seperate the fuel tank vent and MC vent lines and run them up under the hood seperately.

 

[timntrucks]

anyone know a source for those vents.. i call memphis and they want 7 bucks a peice

 

[Tinwoodsman]

White Owl - $6.50

 

[MSeriesRebuild]

My PTO seals are linking a little also. Maybe with the vent now all that will stop. Well maybe..

By all means check that vent; if it's plugged or clogged, pressure build up will cause leaking at the point of least resistance.

However it is typical for PTO shifter shaft seals to leak. Quite honestly the seals used by the military are far from high quality. Instead of the double lip seals of today, they used seal types that have an inner lip of either neoprene or leather and an outer felt wiper seal. The thing about the outer ring of felt is that the felt will attract and hold water like a sponge. This trapped moisture in turn will cause rust pits on the unplated shifter shaft. Once rust pits are there, replacing seals all day long won't stop the dripping. New double lip modern day seals are easy to install, but if you see pits on the shaft; it is a waste of time replacing seals until they have a smooth, non pitted surface to mate against.

We have built many of the transmissions and PTO units. An overwhelming majority have rust pitted shafts. We install new stainless steel shifter shafts along with new double lip seals. This will solve the dripping issue once and for all since rust pits don't occur on the stainless shafts. This is the only cure for the drips we have found that takes care of the issue for good.

 

[MSeriesRebuild]

anyone know a source for those vents.. i call memphis and they want 7 bucks a peice

Your local CarQuest jobber

 

[gringeltaube]

......... However it is typical for PTO shifter shaft seals to leak. Quite honestly the seals used by the military are far from high quality. Instead of the double lip seals of today, they used seal types that have an inner lip of either neoprene or leather and an outer felt wiper seal. The thing about the outer ring of felt is that the felt will attract and hold water like a sponge. This trapped moisture in turn will cause rust pits on the unplated shifter shaft.
.................. An overwhelming majority have rust pitted shafts.
...........................

Agree on most but..... as long as the little rubber boot stays intact it will prevent most of this from occuring in years. The problem is where to find the GOOD, long lasting ones????
With stainless steel shafts, do you skip them entirely?

By all means check that vent; if it's plugged or clogged, pressure build up will cause leaking at the point of least resistance.

How could pressure build up inside the tranny if the input shaft has no seal at all and the bellhousing is normally vented at the bottom, through the "missing" plug

G.

 

[timntrucks]

charles is one super great guy and really knows his stuff.. he has helped me out many times working on m37.. a very big help

 

[M35A2-AZ]

By all means check that vent; if it's plugged or clogged, pressure build up will cause leaking at the point of least resistance.


We have built many of the transmissions and PTO units. An overwhelming majority have rust pitted shafts. We install new stainless steel shifter shafts along with new double lip seals. This will solve the dripping issue once and for all since rust pits don't occur on the stainless shafts. This is the only cure for the drips we have found that takes care of the issue for good.

Now that sounds like a great Idea!!!!