Hi guys,
I haven't been on the site in quite awhile. No excuse really!...just busy with other things and not able to use the Barth much recently. Hope all is well with everyone!
I have always suspected I had a slow leak with the air brake system, as it seemed to take longer than it should to reach adequate pressure upon start up. Now, it won't hold pressure above 40-60 lbs. Went looking for leaks, and the first one I've found is on the right side of the engine just below the injector unit. The small,round device/switch/sender to the right of my flashlight in the photo was leaking air out the back (facing engine and down)fitting, where there was no hose attached. When I placed my finger over this fitting to block the flow, I heard another hose blow off a fitting about 2-3 feet forward (the hose shown coming off this device runs forward, but I haven't yet located where the other end blew off). Any ideas as to whether this is my problem, and what hose (or cap?) should be on the fitting facing the engine? Or where the forward end of the hose that blew off attaches? First time I've messed with air brakes, and any help would be greatly appreciated.

HI Vince:

That round device is the vacuum generator and they are known to go bad with life. It is a Bernoulli style generator and requires air flow thru a venturi to generate the vacuum. The regulator or generator or both may be defective. However, if your system can not make it over 40 psi, you ha e a MUCH more serious leak some where.

On my Breakaway I found years ago the main line from the air pump to the dryer had been abraded against a sharp corner of the oil pan and finally wore thru. If after you shut down, you can hear air somewhere besides the vacuum generator, you have a air leak after the dryer. If you do not hear anything then I think it is the main supply hose. move things around a bit and it should get worse if it is a worn or fractured hose.

YES, if you block the output of the generator as you have done, it will blow the supply hose off the generator. That is not the trouble I am sure. Even if the generator is going full I don't believe that amount of air would be more than the pump could supply particularly if you rev up the engine.

HTH

Hi Ed,
Nice to hear from you. And thanks for the quick response! I'd say my system dropped to making maybe 60 lbs. when I was driving and noticed the problem...and maybe 50 or so at idle when I was looking for the leak. A few questions...is there supposed to be a hose hooked to the nipple on the back of the generator...facing the engine? This is where I heard a lot of air coming out. Hadn't noticed that before at shut down (should there be air releasing from this open generator fitting normally?). It was quite loud, and I didn't hear any other leaks. Also, when I blocked that nipple, the vacuum hose that comes off the front (opposite the one I blocked facing the engine) didn't blow off at the generator, but rather 2-3 feet or so forward. Where should that be connected back up? I didn't see where it came loose from.
From what I've just clarified, are you saying you still think this generator is bad? Or does that always leak air out the open back fitting?
You also mentioned a regulator. I'm not sure what that is...a separate unit I assume?
Also, if I need to be looking at the supply hose as you mentioned because there is no leak at shut down aside from the generator, you're talking about the hose from the pump to the dryer...is that right? I don't actually know where the pump is, but know where the dryer is, and I'm sure I can find that.
Thanks again for the help!

I hate air leaks! I can't hear them and Marleen can't tell me where to look. Big battle of the spouses. Barth is pretty simple.

I agree with Ed, forget the vacuum generator. You got bigger problems somewhere else. First you have two air tanks. Is either coming up to pressure? If one is and the other isn't that rules out the compressor and govenor. If neither is coming up to snuff then you have a problem with the air supply. Assuming (and don't) that the hoses are all good then you have the dryer, the compressor and govenor. Change the govenor as it is cheap (under $25 for a rebuilt).

Thanks Gary. I understand completely about the difficulty in finding the source of these types of noises! My approach so far has been to shut it down and then run or crawl around quickly hunting for the leak myself!
Anyway, I have pressures that are within 20 pounds or so of each other with neither coming up to full pressure, so it sounds like the air supply as you and Ed pointed out. A hose, the governor, or even the compressor. I'll get in there and try to listen for it, and check the hoses for leaks. Where do I find the governor (no idea what it looks like) by the way, and any suggestions on where to buy one? Also, just to put the vacuum generator issue to bed, SHOULD there be anything attached to the nipple that faces the engine, or is that just supposed to be open so it can constantly vent? I don't see a hose near it, but I'm not sure if I should be looking for one that popped off the fitting.
Thanks again.

Greetings from Istanbul Turkey:

NO there should not be anything, hose or otherwise connected to that nipple off that vacuum generator.

Again if there is air coming out of that nipple, it will not be enough to deplete your tanks to the point where the air pump can not keep up. If air is coming out continuously then you have a vacuum leak at the cruise control unit, OR a defective vacuum generator.

BUT that is not your air pressure problem.

The air compressor is located under the engine fuel injection pump. There will be a braided line coming off the back of the head of the pump, toward the rear of the coach. the regulator that Gary refereed to is on the pump also but on the front side of the head of the compressor pump. The regulator is a small round device that it attached to the pump with 2 bolt and has 2 or three hoses attached to it. I guess I would start there first UNLESS you find the main hose from the air pump to the dryer compromised.

Leaks like yours (and the one I am having now) are really hard to find. If you can not build pressure, that leak will have to be heard or seen while the engine is running.

You can mix some dish washing detergent and water, put in a spray bottle and spray around all the air lines working your way from the air pump to the front where all the hoses are manifolded for the brakes, gauge and emergency brake valve is.

Good luch

Istanbul, wow! I hope you're enjoying yourselves over there!! Thanks so much for the very helpful answer. I'm just sorry that I caught you travelling. Much appreciated that you took the time to get back to me on this from vacation!
I'll follow the advice, and hopefully I'll get lucky on locating it. We'll see. BTW, I am assuming that the regulator you are referring to is also the governor that Gary mentioned...that they are one and the same. Sorry for the dumb question, but just to clarify. Anyway, both you and Gary have given me a headstart here. Many thanks. And enjoy the rest of the trip!

You could have a valve sticking on the air dryer. Look and fell the bottom of the dryer to see if air draining out the bottom of the dryer.

Yes, regulator and governor are the same.

probably be withyout internet from this point on, good luck if I can I will watch and comment.

No sweat Ed. Just have a great trip. Sorry I bothered you over there! Had no idea you were out of the US, much less in and around Istanbul. Enjoy!

Thanks for the hint on the sticky valve on the dryer. Will watch for that to make sure.

quote:

Originally posted by vince900ss:
Thanks for the hint on the sticky valve on the dryer. Will watch for that to make sure.

A sticky valve on the dryer can be caused by a weak "D-2 Air Governor". what happens is the Air Governor/Regulator/D-2 Gov is supposed to vent air out of the unloader port and force the compressor into a build mode. If the gov is sticking the blowoff on the dryer hangs open. The cost of a D-2 Gov is cheap - typically around $20.00.

not all ways the RED hoses in the front have a chances to crack without splitting had that problem for months.
lenny

Not weighing in on the specific problem asked about, but coming with a tip for finding air leaks, vacuum leaks and other little noises, especially for those of ya's, like me, who no longer have perfect earsight.

Grab a small piece of rubber hose or plastic tubing, about the length of your arm and small enough to fit in your earhole. Stick one end in aforementioned earhole and wave the other end around the area you suspect the noise to be coming from. Trace along air lines, vacuum lines, at the fittings, etc. or anyplace you suspect the noise is coming from.

Even when you're nearly deef, like I am, when the end of the tubing gets right over the leak, you'll know it.

Good tip. I'm gonna try it.
When my wife's been talkin at me for awhile without a response; she says ... "I'm deaf in one ear and can't hear outta the other!"
Don

quote:

Originally posted by Pauly:
Even when you're nearly deef, like I am, when the end of the tubing gets right over the leak, you'll know it.