Familiar Oil Spray Pattern?

[rumplecat]

My new to me M936A2 was delivered a month or so ago, I drove it about three miles to a storage site, it has been sitting since. I have aired up the tires manually since the CTIS is having problems. It sat for three weeks very uneventfully until this week. I go by a couple of time a week just to check on thinks and when I drive behind the wrecker I see a oil spray pattern behind the drivers side rear wheel. The truck has not had air in a couple of weeks, but this tire is now about 40 lbs lower than last week. The under side of the wrecker has a good coat of oil from what I guess is this leak! Any ideas?

 

[Suprman]

Above the axle is a ctis quick release valve. It should have a rubber duck-bill looking thing on the end. Insert finger look for significant amounts of oil. Bad ctis hub seals can end up blowing hub lube out. Although nowheres near the amount you have all over.

 

[Piper Cub]

Do any hydraulics for the wrecker bed run underneath the rear in that area?

 

[shadowdd]

I would check the rear axle output shaft seal.... That looks very similar to it. Also drive a distance and then when you park it take out the axle vent, if you hear a ppsssttt from the axle then replace the vent. I had mine build up too much pressure in the axle and made the same spray pattern across everything back here. It's worth a try!

Bryan

 

[mcmullag]

Good thread below on replacing the seal.
Me thinks it is the seal behind that flange thing that spins on the top of the axle. My first 5 ton sprayed oil everywhere from that seal when I first picked it up from auction and started driving home.

http://www.steelsoldiers.com/showth...cover-removal-on-a-M939&p=1660570#post1660570

 

[rumplecat]

Guys thanks for the comments, I will check. The think that baffles me is the fact that the truck has been idle with no air pressure on it for three weeks and then suddenly it lets loose? And now the tire is low on air, any way it could be my pressure source to force the oil spray? It makes me think the two are connected some how? I am going to soak the oily area with Purple Power full strength and take it to a car wash. Maybe the source will reveal itself, and I will check the vent in the mean time.
James

 

[Suprman]

If you have a bad ctis hub seal when the system comes on and starts to fill the tires, air pressure feeding that wheel will be significantly lower than intended due to it escaping via bad hub seal. It can see pressure low enough to hold open the wheel valve and dump air out if the tire thru the quick release valve. Taking your hub lubricant with it. Maybe you had some water in the tire and that mixed in too.

 

[Csm Davis]

Okay I think you have two different problems the tire has a leaky seal somewhere try putting a valvecore in the valvestem and reinflating it. The oil is a slow leak from the wrecker body that will run out there because of the low tire tilting the body that way just a little.

 

[rumplecat]

Back to the drawing board, axle vent is good, no oil leaks on any of the hydraulic lines, no air leaks on the tire, CTIS vent is kinda dry and the full moon has passed! Any other ideas?

 

[Suprman]

What if water was running in that direction like Csm Davis said, because the tire was low in that corner. Andwhatever oil was on the bed built up over time just ended up washing down onto that area. A lot of stuff seeps over time when sitting there is always a little oil here and there. Why don't you wash the whole thing down, top to bottom. And then give it a few days and see what happens. Then go from there.

 

[rumplecat]

I am going to give it a wash this weekend if it is above freezing. The oil spray is just that it sprayed out from the interior of the wheel hub area, the air brake pod has the heaviest concentration of oil on it! It was under pressure on a truck with no air pressure on it for two weeks! The only pressure source was the tire! Look at the pattern it was not dripped there, and beside it has not rained.