Need some advice with diagnosing a rear axlel oil/transmission leak on a M923

[Sbrown777]

Hey guys, I'm new to the steel soldiers community and it's my first time posting on here so forgive me if I don't quite have the proper forum etiquette. I've looked through the TM's but I figured some of you might have had a similar problem and any advice is appreciated.

I recently purchased an M923 from a private party and it was rebuilt in 2007 by the RedRiver Army Depot. I drove it from San Antonio to Houston with no issues. Yesterday I started it up and drove it about 60 miles round trip on the highway and when I parked it back at the house I noticed a big leak coming from underneath the rear-middle axel/differential/transmission area. The leak was pretty substantial and hard to diagnose where it was coming from since everything appeared to be caked in oil. One thing I noticed was the oil had sprayed all around the area and even looked as though it had gotten flung up underneath the truck bed and was dripping from the bottom of the truck bed. There was even signs of spray on the tailgate from where the wind had carried it. My question is, any thoughts of what might have caused this? Are there seals in the differential or transmission area that are prone to leakage? I'll attach some pictures that show the area I'm talking about. Any advice is appreciated. Thank you.

ps. One more question from a military vehicle amateur: After driving my 923 for 60 miles on the highway on a hot day, when I parked the truck there was a hissing sound coming from the engine compartment. Upon inspection of the radiator area, there was a pin-hole sized valve that was venting a large volume of air out of the radiator itself after the truck was turned off. Is this normal? If so, what is it? Thanks.

 

[Csm Davis]

Okay that looks like a Pinon seal. Need a picture of the hole in radiator.

 

[Sbrown777]

Thank you CSM Davis, are pinion seals pretty easy to obtain? Any vendors you recommend? Here is a picture of the device/part the air was shooting out of. The air was also very hot to the touch.

 

[Csm Davis]

That's the shutterstat it controls the fan clutch. Lots of threads on how to rebuild them, and pretty sure you can find the Pinon seal in the classifieds.

 

[Sbrown777]

Thanks! Appreciate the help.

 

[Tow4]

Search for: "Rockwell 5 Ton Pinion Seal M809 M939 M54" on Ebay and you will see several options.

 

[Sbrown777]

Thanks for the info Tow4. Are you a banner towing pilot by chance?

 

[73m819]

BEFORE you tare into your truck, remove the axle vent, make sure it is working, if not replace it or install a vent tube system, this vent is the NUMBER ONE cause of axle, transfer case leeks. If when you pull the vent and here air escaping, that will be a good chance the cause of your leak. REMEMBER seals just do not leak for NO REASON, Fix the reason for the leak OR the leak WILL BE BACK.

 

[dawico]

BEFORE you tare into your truck, remove the axle vent, make sure it is working, if not replace it or install a vent tube system, this vent is the NUMBER ONE cause of axle, transfer case leeks. If when you pull the vent and here air escaping, that will be a good chance the cause of your leak. REMEMBER seals just do not leak for NO REASON, Fix the reason for the leak OR the leak WILL BE BACK.

That is very good advise. When I removed mine they all gave a little hiss. Not much, but enough that I was glad I replaced them. Most of my pinion seals are leaking too, but nothing like the OP's. I went with a brass fitting and hose BTW.

 

[Tow4]

Thanks for the info Tow4. Are you a banner towing pilot by chance?

I used to tow banners years ago. I tow gliders now.

 

[Sbrown777]

Thanks guys for the advice and quick response. I'll look into that axle vent first.