URGENT. What might this leak (see picture) be, and will I need a tow?

Five days ago, I noticed a small leak accumulating around my right rear drive wheel. The color is dark brown with foam on the top. The leak has since grown bigger.

Here is the latest picture:

http://bit.ly/sj960p

Does anyone have an idea what it is? I'm thinking hydraulic fluid, but I'm not sure. I'm also thinking a recent cold snap brought about the leak, if you recall the Challenger disaster, o rings, and frost, decades ago.

The bus is 15 years old with 130K miles. Prior to my buying it in September, it spent over three years stored in a barn north of San Francisco.

My concern is that it is not drive able and that I will need to have it towed to a bus garage.

I will appreciate any insights.

Oh, and Merry Christmas everyone.

Dave,

If I had to guess, I would say it's oil from a wheel seal, but that would be easy to determine. Just use a flashlight from the opposite side underneath and if it's a wheel seal, you will see oil on the inside of the wheel and tire.

Dave,

I agree with Tom, a wheel seal leak would be my first impression. If you have a wheel seal leak, it will be easy to detect, as Tom mentioned.

However, if your coach is equipped with hydraulic stabilizers on the rear wheel axle, hydraulic fluid can leak from the stabilizers if you have a seal failure. The stabilizers are an option that some coaches have to compensate for the lose of weight lifting capacity when the steering wheel is turned to one extreme or the other and the tag axle air bags are released. These hydraulic stabilizers will engage when the system detects a steering wheel extreme turn and support the rear end.

To detect this type of oil leak, raise the coach with the air bags and look under the coach, my stabilizers are mounted the rear axle, look for a set of "shock absorber" type of devices with oil lines going to them. If they show evidence of oil leakage, then you have found the problem. These stabilizers are controlled by a mechanism mounted on the chassis vertical wall, in front of the the rear differential gear set.

I do not recommend crawling under the coach without body support jacks. You should be able to look from the side, with a flashlight and see if this is the problem. You can order the seals for the hydraulic cylinders from Prevost. I rebuilt my cylinders. Not a big deal, just messy. If you replace the seals, you will need to purge all air from the cylinders before placing back in service. Their is a process for assuring all the air is purged from the cylinders. Not a Prevost process, but common sense.

Good Luck,

Hector

Hi David. Depending on distance, you may be able to drive to a shop. The alternative , other than tow, is to order new seals and have a mobile mechanic do the change out.

From the looks of the oil it's long past time for a complete differential flush and change. I'm not a big promoter of synthetic oils, so I would just use a high quality lube.
If it were in our shop we would replace both sides of the drive axel.
This would be the perfect time to have a good technition fully inspect the running gear of your coach. You may spend what seems to be big money today, but trust me, on the road problems are very expensive.

My concern about that leak is the size of the puddle. To determine if it is a hub seal just smell the oil. Differential oil has a unique smell.

Driving with what appears to be a huge leak is a risk that the bearings will not get sufficient lubrication and the consequences of that could be very expensive. Having said that, all my concerns are lessened if the bus is sitting on a slab that slopes a lot towards the leaking side. That doesn't mean the seal is OK, it just means the leak is exagerated. But I would err on the side of caution and just have the hub seal(s) replaced where the coach sets unless someone is willing to get under the coach and top off the differential.

NOBODY SHOULD GET UNDER THE COACH UNLESS IT IS SUPPORTED PROPERLY.

Thanks to everyone for their educated guesses. I can now deal with a shop from a position of strength. Many, many thanks.

I should haved added to my post that the substance -

1. Has a smell
2. Foamed on contact with the concrete floor
3. Is quite light in viscosity; it spread rapidly through a paper napkin

I'm going to chance it and drive the bus to a good truck repair shop at the opposite end of the industrial park where my bus is stored.

Regards,

If it foamed on contact with the concrete floor it sounds like compressor oil from the air conditioning compressor.

Once again, can you see the inside wet tire from the opposite side?

possibly inner (not outer) wheel seal leak.

but, do you have Howard Active Steering?