Oil in brake air tanks

[dansawyer]

The Chassis is a 2002 National Tradewinds with a Cat 3126E 330HP engine. The air system and the brakes are operating normally. There is noticable oil on the air release from the air dryer. I opened the petcocks on the air tank. There was between one and two tablespoons of what looks like engine oil drained from the rear brake tank and almost nothing from the front brake tank. The front air brake mechanims are nearly clean. The rear mechanisms are noticalbly oily, not driping, by definitely covered with a light coating.

The coach is new to me. It could have been years since the petcocks were opened.

I now plan to replace the dryer cartdrige.

I have driven the RV about 1000 miles in total. I will check after another few hundred.
What else should be done?

Is it necessary to replace the compressor?

Is it sufficient to replace the dryer cartridge?

Should I flush the lines / tanks with clean air?

Thanks Dan

[Cat]

Its not to unusual to have a oily sludge in air tanks especially if they never been drained. I most people don't know they are suppose to, don't know what means, or mostly don't care.( I'm getting to be a cranky old man- my wife says I've been there for awhile) anyway yes do your air dryer then I would just monitor how much oil you continue to get into the air tanks.
I do not think its necessary to replace the air compressor now. It can be difficult to clean out air lines and tanks. There are isolation valves and plenty of twists and turns that make hard to clean out. Safe Travels

[twinboat]

Oil in the air tanks is a sign of a failing compressor or its running to much.

If your air dryer is purging often, without using the brakes, then you have leaks.

Your rig should sit running at least 5 minutes before it purges from the dryer. If its happening sooner it may have leaks.

[mackwrench]

1st thing is to replace the dryer filter. If oil is getting to tank, then filter is saturated. When you get it off, if the base is oily, then the only way it gets there is from compressor. Oily mist looking, I'd probably rock on....but lots of oil, means compressor replacement.....or as twin posted, compressor is constantly running/pumping due to air leak.

Don't use tools to tighten the dryer filter, hand tight only.

Since you're new to this coach, I'd R&R dryer filter, maybe even rebuild dryer, if it's a Haldex simple job.

Once filter/cartridge is replaced, drain air tanks daily or weekly and see if your still getting it.
Keep in mind it'll take a while to get it all out....

[dansawyer]

Thank you all. I have ordered a new cartridge. The dryer is a Wabco Meritor. I will start with the new cartridge and the inspection.

I don't think the compressor is running full on. When starting out the pressure builds to the cut off point. I have noticed the air pressure can vary by 20 psi or more. That to me means the compressor is not running full time.
The petcocks were frozen / very stiff. It took WD40 sitting for a couple of days before I was comfortable with the force it took to open them. The vehicle was on a slite incline and the petcocks were on the low side. I think I got most of the oil.

I will pay attention to the oil remaining in the dryer.

Thanks Dan

[Ray,IN]

In your case it might be simpler and lest long run costs to simply replace the entire air dryer assembly; as the 4 valves in the dryer body are sure to be gummed up or ruined.

[twinboat]

Did you open 3 tank drains ?

One of your tanks may be a 2 section tank. The shorter section is called the wet tank.

It's the first stop for the air out of the air dryer and collect most of the moisture and oil. No gauge on that tank.

[Ray,IN]

Originally Posted by twinboat

Did you open 3 tank drains ?

One of your tanks may be a 2 section tank. The shorter section is called the wet tank.

It's the first stop for the air out of the air dryer and collect most of the moisture and oil. No gauge on that tank.

Yup, when the air dryer is faulty the wet tank is intended to collect most of the moisture that gets through. On old HDT's without air dryers the wet tank had to be drained daily at a minimum.

[vseasport]

Originally Posted by dansawyer

Thank you all. I have ordered a new cartridge. The dryer is a Wabco Meritor. I will start with the new cartridge and the inspection.
Thanks Dan

Be sure to dump and purge all the air pressure out of your system before attempting to remove the old cartridge.

[dansawyer]

Twinboat,
There are 4 drains total:

The compressor drives a tank with front and rear drain valves.

That tank drives 2 tanks:
a tank in the front with one drain (front brakes)

a second with a third tank in the rear (rear brakes) with a drain
( I have managed to drain the 3 drains in the front. I have not been in a position to get to the rear drain yet. )

Dan

[cmckenzie]

First thing to do is check if you have an air filter on the air compressor. If you do it’s about 3 inches round. Probably the filter needs replacing if you have one??
If you don’t see an air filter then your air compressor gets it’s air from the engine air filter. Old style air compressors get there air on non turbo charge side of the air inlet.
New style air compressors get air from the pressure side of the turbo charger or charge air side of the turbo. They do this to keep the cost of the air compressor down. More air into the compressor.
So this is where things get interesting. On old style compressors you just remove the air compressor discharge line and if you found oil you needed to replace the air compressor. Worn out compressor rings or broken rings.
New style air compressors that get there air from the charge side of turbo charger complicate things now.
You still could have worn out or broken compressor rings but now you also have turbo charge air going into the air compressor and into the air intake of the engine. So now you also could have a turbo charger leaking oil out into the charge air or pressurized air intake system.
You can have 2 sources of oil that can get into your air system.
Easy to figure out. Remove the turbo compressor side air tube. This is the air tube going to the charge air cooler. If you see oil you need to change your turbo and remove your charge air cooler and clean out the oil.
If the charge air tube is clean and dry you need to replace the air compressor, then change the air dryer filter and the purge valve in the air dryer. Purge kit is separate from the air dryer filter.
Open all your air tank drain valves and let the oil drip out.
Then remove the air compressor charge line and pour in methyl hydrate about a quart. Reinstall charge line. Run engine until air compressor reaches 120 psi. Release brakes and cycle the brake pedal to get the methyl hydrate though the brake system. Drain your air tanks again. You might have to do it a few times to get the majority of the oil out of the system.
Do not ignore the oil in you air brake system.
Check and repair now while your at home rather than braking down and having to pay through the nose for a repair.

[Ray,IN]

Originally Posted by dansawyer

Twinboat,
There are 4 drains total:

The compressor drives a tank with front and rear drain valves.

That tank drives 2 tanks:
a tank in the front with one drain (front brakes)

a second with a third tank in the rear (rear brakes) with a drain
( I have managed to drain the 3 drains in the front. I have not been in a position to get to the rear drain yet. )

Dan

The tank near the rear axle is a storage tank for the rear air springs only.

[dansawyer]

Originally Posted by cmckenzie

First thing to do is check if you have an air filter on the air compressor. If you do it’s about 3 inches round. Probably the filter needs replacing if you have one??
If you don’t see an air filter then your air compressor gets it’s air from the engine air filter. Old style air compressors get there air on non turbo charge side of the air inlet.
New style air compressors get air from the pressure side of the turbo charger or charge air side of the turbo. They do this to keep the cost of the air compressor down. More air into the compressor.
So this is where things get interesting. On old style compressors you just remove the air compressor discharge line and if you found oil you needed to replace the air compressor. Worn out compressor rings or broken rings.
New style air compressors that get there air from the charge side of turbo charger complicate things now.
You still could have worn out or broken compressor rings but now you also have turbo charge air going into the air compressor and into the air intake of the engine. So now you also could have a turbo charger leaking oil out into the charge air or pressurized air intake system.
You can have 2 sources of oil that can get into your air system.
Easy to figure out. Remove the turbo compressor side air tube. This is the air tube going to the charge air cooler. If you see oil you need to change your turbo and remove your charge air cooler and clean out the oil.
If the charge air tube is clean and dry you need to replace the air compressor, then change the air dryer filter and the purge valve in the air dryer. Purge kit is separate from the air dryer filter.
Open all your air tank drain valves and let the oil drip out.
Then remove the air compressor charge line and pour in methyl hydrate about a quart. Reinstall charge line. Run engine until air compressor reaches 120 psi. Release brakes and cycle the brake pedal to get the methyl hydrate though the brake system. Drain your air tanks again. You might have to do it a few times to get the majority of the oil out of the system.
Do not ignore the oil in you air brake system.
Check and repair now while your at home rather than braking down and having to pay through the nose for a repair.

I have just gotten back to this. A couple of questions:
First poor the methyl hydrate in where:
a. the air intake into the compressor?

b. disconnct the air outlet from the compressor and poor it in before the dryer?

c. disconnect the air outlet from the dryer and poor it in there?

Second, what is the purpose of the methyl hydrate?

a. Is is an oil solvent?

b. will it hurt the rubber in the brake components is the 30 minutes or so it is in the system?

(I have not used methyl hydrate and am unfamular with its use or characteristics.)

[Ray,IN]

dansawyer, I've also never heard of methyl hydrate. I do know to never pour liquid into the air intake of any piston motor/compressor. Liquids do not compress, they just wreck compression motors/compressors.