The air pressure on our 93 GV goes from full to empty in about an hour after killing the engine. We just spent 3 weeks at MOT having several things repaired, the air leak was supposed to be one of them. The air bags do hold air much better than they did but the tank pressure still leaks like a sieve and I'm trying to locate the source of the leak. The throttle started make a slight hiss a while back but today on our way to Eureka Springs it really started leaking while being depressed. So there's one leak and I'm hoping that I will be able to remove the throttle assembly some how and repair that leak while we're here. I have crawled around the coach but haven't been able to locate any other leaks. Is there any specific places that are more prone to leakage?
Thanks,
Tyler and Hannah
Kiddie bubbles are your friend.
That size leak should be easy to find.
Yes, it could be several smaller leaks, but if it bubbles it is bad.
Do you have a step cover? The control under our steps started leaking bad on a trip.
That's what I thought as well. I figured that a leak that substantial could be heard and have spayed a lot of what I can access easily with soap and water but with no luck. I will continue the search! Haha
We do have an air controlled step and I have not checked it! That will be the next place I check! Thank you :)
It might only leak when closed, open, or both. So check both
Tyler,
Here is a link to the info you need for the treadle valve leak you are talking about. Williams Controls WM453109 Air Throttle Valve (http://www.foreforums.com/index.php?topic=27762)
You could have the check valves or related piping on your air tanks leaking air back into the air dryer. Here is a link to one of Chucks air leak repairs that may help you out.Air Tank Valves R&R (http://www.foreforums.com/index.php?topic=27638.0) Chuck is the go to guy when you have an air leak on a early 90's GV. When he sees this thread he will chime in.
Here is another thread that may help you out. Wet Tank Air Leak Fixed (Accidentally) (http://www.foreforums.com/index.php?topic=29262.0)
Pamela & Mike
I like this stuff for leak detection.
Amazon.com: Snoop Leak 8OZ-SNOOP Snoop Leak Detector, 8 oz.: Industrial &... (https://amazon.com/gp/product/B00H895GH8/ref=oh_aui_search_asin_title?ie=UTF8&psc=1)
It is a never ending quest. Kind of a game we all play. Sooner or later you get the really big ones and then get used to the small ones. Check the pressure protection valves on each of the two tanks. Mine both leak, I have replacements when I get to it. I also have a right rear ride height valve with a slow leak too. Replacements in my spare parts tub for when it becomes more annoying. Same with check valves. Sooner or later they all leak.
Prioritize. Fix what needs fixing now that prevents fun.
I use this for air and refrigerant leaks, bid blue
Tyler,
Those threads that Pam/Mike linked (above) have some good info in them. I have been poking around my air system for 5 years looking for leaks. I still haven't found all of them. Like most members, I've got our coach to where I can live with it, and that's good enough for me.
Do you have the air system schematic for your coach? It is very helpful in understanding the flow of air through the system.
Besides all the places mentioned in my old threads, here's some places you might check when you get a bottle of soap solution. Any air pressure regulator is suspect - they all seem to leak eventually. You should have one up at the front of your coach, just in front of the two air tanks. There is one under the steps that controls pressure to the step cylinders. The Bendix cruise control and air throttle assembly mounted on a plate on the engine compartment wall has several components that might leak. Another place where I had a leak was the parking brake control. I rebuilt it:
Bendix PP-1 Repair Kit (http://www.foreforums.com/index.php?topic=27892).
Thanks so much to everyone for the responses! I hate to admit it but I'm really out of my element with this coach. Things continue to go wrong at such a pace that I cant keep up. Add on top of that my lack of knowledge and not having a place to actually work on it only compounds my anxiety. The guys at the shop replaced 3 solenoids on the back six pack and the entire assembly for the front along with the petcocks for the tanks. They also fixed some other leaks in the system that they found. I'm a bit at a loss because they gave us the impression that we were good to go. That's neither here nor there now but if they couldn't find it I'm not sure how I'm supposed ha! We will read through all of the information that everyone provided and keep trying to chip away at it. We don't have a choice but to. Thanks again to everyone, we'd be totally lost if it wasn't for the people on this forum.
I know it seems overwhelming at first, but you will work through it. I had absolutely zero knowledge of a diesel motorhome with air brakes when we bought ours. Had to learn it all 100% from scratch. This Forum helps a lot. For any question you have, try to use the search function and pull up appropriate old threads. More than likely there will at least be helpful information, if not the exact answer. If you search and don't find what you need, then ask! We'll help all we can.
Chasing air leaks is ongoing project. Look at it as a regular maintenance issue.
I'm like Chuck, when I first started researching motorhomes, I couldn't even spell diesel let alone know what other systems would be involved. Have I felt overwhelmed? Yes many times. But with the help of this forum and its search capacity, the great people willing to help with their time and advice and learning about my coach, I have come to enjoy figuring out how to fix and/or improve various items on my coach. In time you will undoubtedly look back and with a sense of pride say "That wasn't so bad, or I know where that problem is and how to fix it."
It is all just a learning curve which is part of the adventure. Yes, I hope to avoid some of the adventures ahead, but they will come and with everyone's help, I'm certain that it will become just another one for the records. When you do locate where your major leaks are, be sure to post what you find so that some other newbie (as we all were once) will find your advice and be able to resolve his/her issue.
Larry
Tho it seems like a slight hiss, the throttle leak may be enough to dump that much. My park brake hisses ever so slightly and when it does the tank drops quickly.
Chasing air loss should be considered a hobby , eternal job.etc. IMHO
On the throttle make sure you check all the air line connections.
Cylinders for the air step check the shafts that come out of cylinder for O ring leaks.
Tank check valves, all of them can cause leak back and I have replaced all 3 of them.
I found the check valve on my air dryer (main line to wet tank) was installed back to front so fixed that. That was first time in Nac after that I rebuild my own now.
Just some ideas.
JohnH
My wife absolutely loves our Foretravel and can't wait to move in full time. I, on the other hand, am often overwhelmed by it. Were it not for this forum I would have bailed. On the other hand, drove back from Albuquerque last month in horrible winds and the exceptional road manners of a Foretravel were on display. I thought it was a little windy, opened the door to get some fuel and the wind nearly sent me flying through the parking lot. I had to use two hands to open and close door while bracing myself and still struggled to control the door. No problem driving. I try to remember this whenever I'm baffled by the air system, fuel system, and electrical system.
Lots of little ones add up. Be patient!
Everyone is right, step is the 1st one. many tech's miss that one.
Went ahead and ordered the throttle rebuild kit chuck linked in his post. It was really dumping the air while using the throttle and has me concerned for safety. I also noticed for the first time that there are two needles on our air gauge. The white needle is perfectly aligned with the red as to make it nearly invisible. I'm not sure if the gauge is broken or if something else is going on but the two have never separated since we've had it.
My wife and I love the coach but at the same time i have to beware of the law of diminishing returns, as there are issues with it that are beyond the reasonable possibility of repair. That is the greatest source of my anxiety. It's a fine line to walk because there is absolutely no way to recoup the money we've invested already let alone the amount it will continue to cost to maintain. Now that it's our only residence though, not maintaining isn't an option.
One needle is for the front air tank pressure and the other is for the rear air tank pressure. It isn't broken as the 2 needles work on separate air feed lines.
Mike
Tyler,
The double needle air gauge is common to the older GVs. As Mike says, two separate air lines to the back of the gauge. One needle shows "front" air tank pressure - other needle shows "rear" air tank pressure. Both of these tanks, despite confusing names, are located under the nose of your coach behind the front bumper. On my coach, the red needle = front tank, and white = rear tank.
Although it is
possible that both needles are always showing
exactly the same pressure, I would say this is very unusual. Personally, I would like to verify the fact that both needles are, in fact, registering actual tank pressure. This can be done with a fairly easy test, but of course first you need to get your air system to the point that it will hold pressure for a reasonable amount of time (like overnight).
When you are ready to try it, see my next post for the test procedure.
Testing components of the coach air system can be fairly simple. To do so, it is most helpful to have the air system schematic for your coach. Without it, working on the system is very difficult. Try this test to check some of the important parts of system.
1. Run engine until air compressor cut-out pressure is achieved. Shut off engine. The entire air system is now at the same pressure.
2. Check (record) the reading on both dash air pressure gauges (or both needles, if single dash gauge).
3. Open the water drain valve on the WET tank (see air system schematic), and allow pressure to bleed off to zero.
3a. What came out of drain valve? Dry air is good. Water, or oily grey "mud", or dry white powder is not so good. Time to service dryer.
4. Check (record) the reading on both dash air pressure gauges (needles).
5. If both dash gauges read the same pressure in step #2 and step #4, then the inlet check valves on the respective tanks are good.
Clarification: With "good" check valves, the "front" and "rear" air tanks should not lose any pressure when you drain the wet tank.
6. If either, or both, of the dash gauges lost pressure between step #2 and step #4, the inlet check valve on the respective tank is bad, and should be rebuilt or replaced.
7. Locate your FRONT air tank (see air system schematic), open water drain valve, bleed off pressure to zero. (See note 3a above)
8. Check dash air gauge(s). One gauge(needle) should now show zero pressure - this is your FRONT tank gauge. Other should still read the same as step 4.
9. Locate your REAR air tank (see air system schematic), open water drain valve, bleed off pressure to zero. (See note 3a above)
10. The remaining dash gauge (needle) should now show zero. This is your REAR tank gauge.
I found the schematic and parts list with the treadle valve on it.
That air diagram is very helpful. See the numbers on the air lines? There are paper labels taped to all the OEM air lines - use them to help you find and identify the other valves and components. The physical location of things on the coach do not necessarily correspond to the position on the diagram, but you can get in the ballpark by tracing the air lines.
From my limited knowledge of air systems, it is not recommended to open drain valves at full pressure. Maybe it is OK to do that once in a while, but should not be a regular thing as I understand it. This can erode the seat of the valve and make things worse. Some thing to consider. Have a great day ---- Fritz
i found a leak in my parking brake switch and one that i chased forever was an air chamber diaphragm
Ok, I found two major leaks and a few not so major leaks. I'm not sure exactly what I'm looking at but do have a couple pictures so maybe someone can help me out. Both of the low pressure switches connect under the brake pedal are steadily leaking. That's the not so major leak. One of the major leaks is coming from what appears to be an air pressure regulator and associated electronic control box located under our entryway stairs. Both the controller and regulator are leaking pretty severely. I'm not sure what it's regulating but I did notice that if it set on say 80 psi it will purge air until the tanks read 80 psi and then it stops purging. It still leaks around the body though. The second sever leak is coming from a valve body that is bolted to the (I'm assuming) the ecm for the throttle. It has an inlet and outlet controlled by two solenoids. It appears to be the solenoids that are leaking. I removed the assembly and Googled the number on the back with no luck. Does anyone know what these things are and maybe how they function?
Forgot to add pictures, sorry.
Let me see if I can help.
The pressure switches under the brake control valve might just need to be tightened up (the fittings). If not, then they can probably be replaced fairly easily. You would have to remove them and see if there is any ID number on them, then do a Google search for a suitable substitute.
The thing under the stairs is a control valve that directs the air pressure going to the step cylinders. The regulator reduces the coach system air to a lower value (60-80 psi) suitable for use in operating the cylinders. You can remove the whole control assembly and take it apart. Might be able to clean it up - possibly replace some O-rings, and return it to service. If it can't be repaired, then you can buy replacement units online. Again, helps to have a part number when you go hunting. There is some info in the threads linked below that might be helpful.
GV Entry Step Actuating Cylinder (http://www.foreforums.com/index.php?topic=30329)
GV (Unihome) Air Step Mod (http://www.foreforums.com/index.php?topic=28607.msg304571#msg304571)
The last one is gonna be tough. Parts for the old Bendix cruise control assembly are like hens teeth - rumored to exist, but virtually impossible to source. Again, if it is the solenoids leaking, it might be possible to solve that with O-rings. You have to take them apart and see what you find. Here is a reference manual for the Bendix unit. Will help you figure out how it works. Also, a "corrected" diagram of the cruise control system, showing the additional parts and lines used on our coaches to add the air throttle function.
When working on the air system, especially if rebuilding valves, and when replacing O-rings, a good lube is essential. I recommend Super Lube.
https://www.homedepot.com/p/Super-Lube-3-oz-Tube-Silicone-Lubricating-Grease-with-Syncolon-PTFE-92003/202932697?MERCH=REC-_-PIPHorizontal2_rr-_-202932687-_-202932697-_-N
An SOB here in the park has an extended warranty (aftermarket). The left rear of the coach is lower than the other three coners lately (airbags) so the owner took it to a dealership for warranty work. When he picked it up the next day they presented him with a bill for $900.00, told him the extended warranty only covered labor, not diagnosis and they had found nothing leaking.
Wonder if they provided complimentary Super Lube when they "presented" him the bill.
Ok, I did a little more investigating and what I found is that vent no. 5 is leaking when the step is down, the step cylinder around the polished rod is leaking when the step is up and the electronic end of the distribution block is leaking at all times. I am going to forgo the attempted repair of any of those issues and instead try to install an inline shutoff valve on the air inlet just before the pressure regulator. I will let everyone know if it works. It also appears that someone has done installed a toggle switch in the bay to control the up and down of the step from there. There is another one below the dash to the right of the steering column that also has something to do with the step, but it doesn't seem to do anything.
There is no lube provided in those type of situations!
Tyler. I and a couple of others have done that idea of adding a solenoid valve to the valve body so when the step is either up or down depending on what you want you just flip a switch on dash and the air is terminated and no more air is lost. I found a great amount of air was bypassing the O ring in main cylinder for step cover and the cylinder could not be taken apart so I left it in and stop any loss of air while driving and this works good. In Beamalarm under Modifications you will see a write up of this and pics.. There is also one on how to wire in a switch to keep the step up when parked, simple wiring job.
JohnH
One leak fixed! It may not be a glamorous fix but it is simple, reliable and effective! The best part is that there's no electronic wizardry involved and in my book I call that a double win! Sure it's not as convenient as a switch on the dash but I'm quite capable of bending down and turning a lever by hand. Now to try and figure out the solenoids in the back.
One little suggestion: instead of teflon tape, the smart kids on this Forum recommend using pipe sealing paste when working on the air system. There is less likelihood of a small bit breaking loose and getting stuck in a valve seat somewhere downstream from your repair.
I've had good results with the product linked below - there are others. Available in most auto parts stores. One small tube will last for years.
Permatex® High Temperature Thread Sealant - Permatex (https://www.permatex.com/products/thread-compounds/thread-sealants/permatex-high-temperature-thread-sealant/)
We had bottles of that stuff laying around when I was building natural gas skids. I'll have to get some for the next project.
It's been a little over 3 hours and we still have 40psi on the dash! We're making progress haha!
It' the little things in life that make it so much fun b^.^d
Larry
I removed the solenoid assembly again to have a go at it but I'm not sure how it comes apart and I don't want to break it trying to figure it out. I'm not too smart with this stuff, that's why I opted for a mechanical valve rather than an electric one on the door step, and if I break this assembly there's a good chance we'll be stuck here. It might be best to reinstall it and look for another one somewhere.
Wish I could help with the solenoid assembly, but I have not tried to take ours apart. It is not obvious from your photos how it comes apart. Best not to break it, unless you have another one in hand. I am afraid that will be a very difficult part to find. I'll see if I can find you any help. Some guys at one of the Bluebird forums were pretty deep into working on these systems. I'll see if I can find some contact info for that group.
Here's a link to the Wanderlodge Owners Group. Some of their coaches use the Bendix cruise system.
Right above where it says: Welcome to the Wanderlodge Owners Group" there is a search box. Put "bendix cruise control" in there and search. You'll get lots of hits to read through. Perhaps you will find something about a source for used solenoid assemblies? Worth a look.
Wanderlodge Owners Group - Powered by vBulletin (https://www.wanderlodgeownersgroup.com/forums/index.php)
Thanks Chuck! I'm on the WOG site frequently just perusing the 'for sale' section as I have a real soft spot in my heart for the Wanderlodge. I'll sign up for an account and ask around as well. It's really cool how these things cross brand lines, like the Newell guys with our air conditioner problem.
Found a old post that may help, if you do want to disassemble the solenoids. Check this out (Reply #329):
What did you do to your coach today VII (http://www.foreforums.com/index.php?topic=33153.msg316676#msg316676)
RVtinker (Mike & Lilli) is active on the Forum - was here today. Might send him a PM if you need help chasing air leaks!
Dang Chuck, you're really on it!
A was able to find a part number which is 065030 according to some old bendix parts catalog. I'll check out that link and see what I can do!
Followed rvtinker's instructions and the solenoids came off easy as can be! :)) I am feeling 100x better than I was a few minutes ago! I'll get some new o-rings tomorrow and see if that solves the problem! Thanks so much to everyone for your help!
Don't forget the Super Lube!
I would have too! Thanks for reminding me, it is on the list along with the thread sealant!
Whenever I work on any of the air system valves or components, I always use the Super Lube. I coat every O-ring and every metal part lightly with lube before reassembling and installing it. Don't get carried away - just a thin coating. Helps hold things in correct position while you assemble the valve. Protects the rubber O-ring surface from "friction" damage between moving parts. It will also actually help fill in microscopic defects in the sealing surfaces within the valve, and thereby (hopefully) forestall minor leaks.
Will not degrade rubber parts, tolerant of high and low temperature operating conditions, water resistant, chemically inert. Excellent stuff!
Went and got o-rings today. Could not find metric ones anywhere but found some at Lowe's that were a near exact match. The box had half of them missing and since it was the only one they had they let me have them for half the price, for a grand total of $1.53. Could not find super lube anywhere but the throttle rebuild kit came in today so I used some of the silicone grease that came with it. No more leaking from the solenoids! I'm pretty pumped that I was able to fix it! :)) The tanks are holding much better now, only lost about 15psi in an hour. There's still some leaks to be found but it's getting better!
Got the throttle out and rebuilt last night. Removal, rebuild and reinstall was pretty easy. Getting the foot pedal back in place was kind of a bugger but I used a piece of braided fishing line tied to the top of the spring to hold up on it and a mirror behind the pedal so I could see what was going on. The pedal took about 15 minutes to install and the rebuild took about the same. I checked for leaks and also the actuation of the throttle cable as per the instructions. There are no leaks and the throttle moves as it should although I'm not sure how to check if it's moving the proper amount. All in all it was a fun project. We're still losing air steadily from somewhere so the search continues!
I'm not sure what the air chamber diaphragm is but would like to check it. Can anyone enlighten me?
Took me a LOT longer than you to get that pedal reinstalled......
Ah, to be young and flexible again. My old body don't fold up so good anymore, and looking through trifocals makes working in close quarters more difficult than it should be.
Glad you got this project done successfully! That's one item that won't need repair again for about 20-30 years. ^.^d
Only "air chamber diaphragm" I can think of is a part of the brake assemblies. Air pressure is used to release the spring brakes (parking brake) on the rear axle. Don't mess with the air brakes or rear spring brake mechanism unless you know what you are doing. That's a job for qualified brake techs.
Photo (not very good) of rear brake can below:
I may have just gotten lucky! We'll go with that because it doesn't happen very often. haha
That's what I was coming up with when I did a search but wasn't for sure. When I was under the coach look for our wet tank I noticed that our brake cans were pretty badly corroded. I'm definitely not comfortable with messing with our brakes!
The brake chambers won't leak until the brake pedal is pushed.
Correct. The parking brake/emergency brake is SPRING applied, AIR PRESSURE released.
So, when parked, should not be source of air leak.
Speaking of air leaks, I have a "waiting to happen" braided stainless steel air line from compressor to air dryer. Is there a reason for it to be so long? It comes out of compressor "I think it is compressor" goes forward to transmission then loops back to back of engine compartment across back to air dryer. It has 2 spots That the stainless braid is missing-- looks like it was kinked!
Would a shorter line do the job?
Thanks
Chris
If that big air line was kinked its leaking. Its that type of stainless nylon hose because of the heat produced by the air compressor. That type of hose can not be kinked no matter what.
Maybe I'll get under there tomorrow and have Hannah hit the brakes.
Chris,
1.The short answer, yes
1a. That hose length is there so the air that has been compressed can have time to cool off some prior to getting to the dryer. I don't remember the exact numbers that Mark (he is the Cummins man that worked on this engine development) gave me but that length was what was determined to work for the Holset compressor on our age coaches. Different compressor/dryer combos have different specs.
2. It would do the job of moving the air from point "A" to point "B"
3, Not good.
Pamela & Mike
There is real satisfaction in finding a problem then creating a solution. When I had a significant air leak, I squirted my bubble mix all over and when I got to the front (engine running) I could clearly hear it. Reaching up to the bottom of the treadle valve, I found the leak and when I plugged the exhaust port with my finger I could make the engine rev! The replacement/ remanufactured valve was easy to get, relatively easy to replace, and it solved the leak.
Now on to the next thing...
Got back under the coach today and found a couple more air leaks. One of the solenoids MoT replaced on the rear six pack is leaking around the base of it. It may just be the o-ring but the surface of the manifold is so rough I'm not sure how they got a seal in the first place. The other two air leaks are coming from the service brake relay valve and the spring brake relay valve. They both look identical and from pictures I found they both look like a service brake valve but how I'm reading the schematic one is the spring brake valve. I could be wrong though. Both have one air line entering and two lines running to the brake cans. Both are leaking from the bottom around what appears to be a circlip. If there is a circlip, maybe they're rebuildable? There are numbers on the bottom (T-294859-C) but I didn't come up with much of anything.
Is anyone familiar with these valves?