Air Leak--Check valve

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Air Leak--Check valve

June 29, 2023, 08:14:38 am

Seems like air leaks are a popular topic these days. I have been pursuing air leaks on my 2015 IH45 for nearly 2 years. Although its a bit like "whack-a-mole," I have been able to make good progress--mostly by spaying lots of soapy water to find and replace air lines and connectors. Reference the attached pic--I found my final big leak [maybe?]. The check valve that isolates the aux. pump from the Active Air tank failed--totally rusted inside. Seems the desiccant bulb on the aux. pump doesn't do a very good job of removing moisture. Issue was likely made worse by previous system leaks that caused the pump to run a bit more than usual.

Re: Air Leak--Check valve

Reply #1 – June 29, 2023, 09:46:24 am

The very first air leak I found on my coach was the top fitting on that check valve. Since I still seem to have some leaks, I guess I need to go and remove that check valve and verify it is working or I guess better yet just replace it.

Re: Air Leak--Check valve

Reply #2 – June 29, 2023, 11:57:19 am

PS--the tricky part with this check-valve leak is that the air leaked back internally thru the aux. pump so there were no external signs of the leak--and it was a pretty sizeable leak too.

Re: Air Leak--Check valve

Reply #3 – June 29, 2023, 04:54:29 pm

On the subject of check valves, I'm confused about the variety of types and costs of the various check valves that are available. Can anyone shed some light on what should be taken into consideration when selecting the proper check valve and what would justify the huge price differences? See examples attached.

Re: Air Leak--Check valve

Reply #4 – June 29, 2023, 05:11:38 pm

Quote from: OldScout – June 29, 2023, 08:14:38 am

Seems the desiccant bulb on the aux. pump doesn't do a very good job of removing moisture.

It's a small load of desiccant for the overall job, particularly in humid conditions. How often are you replacing/re-drying and re-using it?

Re: Air Leak--Check valve

Reply #5 – June 29, 2023, 05:51:51 pm

The short answer is never in the two years I have own the rig--engine drier yes; this drier nope. Fully appreciate the need to service the engine drier but haven't messed with the pump drier--didn't really think about it/nobody mentioned it. This does beg the question, though, as to whether the aux. pump desiccant system in the 2003 era FT is different from the one in the 2015IH? The one on the 2015 looks more like a small filter in the bulb and appears totally inadequate to the task of drying the aux. pump air volume.
PS--Geomann--I asked the same question on pricing after my research. Though, both Wabco and Haldex are recognized air brake suppliers. Fleetpride also found a Bendix cross-ref number for me--but no price. The first valve on your post looks a bit like the OEM in mine rig, except mine is female to female; the second is an apparent match; the third looks like brass--good for moisture; and the fourth looks like any number of valves on Amazon and Ebay???

Re: Air Leak--Check valve

Reply #6 – June 29, 2023, 06:05:51 pm

Quote from: OldScout – June 29, 2023, 05:51:51 pm

The short answer is never in the two years I have own the rig--engine drier yes; this drier nope. Fully appreciate the need to service the engine drier but haven't messed with the pump drier--didn't really think about it/nobody mentioned it. This does beg the question, though, as to whether the aux. pump desiccant system in the 2003 era FT is different from the one in the 2015IH? The one on the 2015 looks more like a small filter in the bulb and appears totally inadequate to the task of drying the aux. pump air volume.

A 2003 has about a 4 ounce (IIRC) capacity. There are indicator crystals that change color as the desiccant is spent, at least with the usual load. It's readily available in bulk; just keep it dry. FOT used to charge $51/dose so I learned to "bag my own". You can find blue indicating, which has cobalt, or green indicating which does not.

We typically changed it out every couple of months, as needed. It can often be revived by baking/microwaving to dry it out so I kept a paint can of spent desiccant for "bulk drying".

Link to my "instructable" Desiccant option for the HWH system

Re: Air Leak--Check valve

Reply #7 – June 29, 2023, 06:19:22 pm

Michelle--very interesting, my desiccant, if it is desiccant, looks more like a pre-formed cone--not too different from what you might see in a small fuel filter sediment bulb. My system also has a fancy electric solenoid dump valve that exhausts out the bottom of the bulb, every time the aux. pump shuts off? I will get a pic and attach it..

Re: Air Leak--Check valve

Reply #8 – June 29, 2023, 07:08:59 pm

I thought I had a good picture of the filter but this is the best I have. Problem is you can not see the filter. Just so happens that FOT has the Air trap solenoid valve on sale. Maybe not since it says May Sales.

On the check valve I have sent Brad @ FOT if they stock. I guess I might find out tomorrow or maybe next week if he has taken a long holiday. I have not seen any except the $100.00 one that is not brass

Re: Air Leak--Check valve

Reply #9 – June 29, 2023, 07:59:08 pm

Quote from: OldScout – June 29, 2023, 06:19:22 pm

Michelle--very interesting, my desiccant, if it is desiccant, looks more like a pre-formed cone--not too different from what you might see in a small fuel filter sediment bulb. My system also has a fancy electric solenoid dump valve that exhausts out the bottom of the bulb, every time the aux. pump shuts off? I will get a pic and attach it..

See here if your system is similar to our former 2003 HWH Filters and Bowls

See also this on the NO solenoid "blow off" valve, which I believe is identical to the electric solenoid dump valve you mention. It has the same function; a 2003-ish has separate bowls for desiccant and condensate.

HWH Solenoid Valve Rebuild

Re: Air Leak--Check valve

Reply #10 – June 29, 2023, 08:26:19 pm

Just purchased one from FOT (about$145).

It comes from HWH.

jack

Re: Air Leak--Check valve

Reply #11 – June 29, 2023, 08:47:43 pm

Quote from: cynjac – June 29, 2023, 08:26:19 pm

Just purchased one from FOT (about$145).

It comes from HWH.

jack

If the issue is the valve seat, get parts (specifically the plunger) from encantotom and rebuilt the solenoid valve to have as a spare.

Re: Air Leak--Check valve

Reply #12 – June 29, 2023, 08:51:13 pm

Michelle--just as I was starting to suspect after your last post--my 2015 system only has the clear bulb and "blow-off" solenoid, similar to what you have on the left. I dont have anything like the desiccant cartridge on the right. Almost seems like FOT abandoned the desiccant function in favor of the owner ensuring they periodically drain the Active Air tank. Problems here are: 1- the steel check-valve seen in your atchmt doesn't like the moisture; and 2- my aux pump feeds three functions: a-the active air tank; b-the aux tank; and a direct feed to the Active Air leveling system in the event the AA tank has emptied and the two DOT tanks are isolated by their protective valves [eg. at 60 PSI or below]. Think parked in a CG for several days, your stored air is depleted, and the AA is triggered to re-level the coach via the air bags.

Re: Air Leak--Check valve

Reply #13 – June 29, 2023, 08:55:07 pm

Scout (I refuse to call you "old"

)

Some have retrofitted a larger payload desiccant vessel in their older coaches - it's basically an air dryer for a shop compressor. If you frequent humid/moist areas like the Gulf coast or PNW, it would probably be possible to plumb in something like that on your coach.

Re: Air Leak--Check valve

Reply #14 – June 30, 2023, 08:11:08 am

Quote from: Geodmann – June 29, 2023, 04:54:29 pm

On the subject of check valves, I'm confused about the variety of types and costs of the various check valves that are available. Can anyone shed some light on what should be taken into consideration when selecting the proper check valve and what would justify the huge price differences? See examples attached.

I do not know if we are hijacking this thread, but I have the same questions. I have to feel that a check valve is a check valve. I ordered two from Find it parts that appeared to be the same threads and size as my "original" check valves and a pop off valve for my wet tank. After I replaced the aux pump tank aka Slide bladder tank, I still had some substantial leaks. All I could find was the pop off valve on the wet tank leaking and it was draining the the two "front and rear" brake tanks. So both check valves appear to be open both ways. As I have removed sensors and valves I find that they have blockage and corrosion at the inlets. I feel my air system is pretty clean and dry NOW, but I am replacing parts damaged or blocked by twenty years of use or abuse. Now that I have direct and constant reading pressure gauges for both front and rear tanks, I can watch real time what is happening with my air. I also remoted the drain valve for the new Slide Out Seal Air Tank to make it easier to check air quality and drain moisture on a periodic basis. Also my original check valves had a part number on a label attached to each valve. This number was Meritor WABCO 9341990030 which Find it Parts shows a Haldex KN23000 as a direct replacement which is what I ordered at $28.84 each, Today they also show a Newstar 8444 as a direct replacement at $10.18 which I did not see earlier when I ordered the Haldex part. I am sure either on will be fine though. I do not know if I have answered your question, but I will let you know how the parts I ordered work out in a few days when I go back to the coach and install them.

Re: Air Leak--Check valve

Reply #15 – June 30, 2023, 08:26:27 am

Herb, the valves to isolate each slide bladder were leaker on my 01. They got replaced when I put vacuum pumps in to suck the bladders down.

Re: Air Leak--Check valve

Reply #16 – June 30, 2023, 09:29:49 am

Fot has check valve RN13526BR which is $63.53 + tax+shipping

Re: Air Leak--Check valve

Reply #17 – June 30, 2023, 10:14:43 am

Napa can match the check valves for about 40$.
You can find rebuild kits for most of the old ones.
Mine are female / male. Some replacements may need a nipple to fit.

Re: Air Leak--Check valve

Reply #18 – June 30, 2023, 11:28:41 am

Just an FYI - when I replaced the check valves on my U320 the new ones came with a "hum" as air was passing through them. Sounded like a harmonic imbalance. Not too loud or annoying, just a new sound. To this day you still hear them every time the coach starts airing up. Just an FYI if you start hearing a noise you aren't familiar with. They work fine and I've heard others report the same.

Re: Air Leak--Check valve

Reply #19 – June 30, 2023, 07:26:28 pm

This has been a very enlightening post for me--it also reminds me that while older and newer Foretravels have a lot in common, there have also been some changes over the years. Think the engine compressor drier does a good job [if properly maintained] of controlling moisture, but without desiccant, the aux air pump can be a major source of moisture in the air system. Other than installing an after-market desiccant system, the alternative is to regularly drain off the tanks. There are also implications for replacement check-valves too--perhaps those made of brass [Haldex?] are a better choice.
PS--interesting comment about the "noise" some check-valves make--mine sound-off for a few seconds as the compressed air reaches about 60PSI. 60PSI is when the protective valves [isolation] open on the DOT tanks and begin filling the other tanks. Be interesting to understand what causes the noise?

Re: Air Leak--Check valve

Reply #20 – June 30, 2023, 07:59:11 pm

Quote from: OldScout – June 30, 2023, 07:26:28 pm

Be interesting to understand what causes the noise?

I suspect it is similar to what makes the noise in a musical wind instrument that employs a reed.

Most check valves consist of a thin spring loaded flat metal plate that sits on a round seat. Air can only flow through the valve in one direction. As air flows through the valve, it lifts the thin plate up off the seat. At some specific rate of flow, the plate must start to vibrate rapidly on the seat, thus generating the weird noise.

Re: Air Leak--Check valve

Reply #21 – June 30, 2023, 09:12:04 pm

Hey Chuck--ref the noise, that sounds right--I had the check-valve apart to clean up the rust, pending a replacement. The innards are exactly as you described.

Re: Air Leak--Check valve

Reply #22 – July 05, 2023, 09:49:02 am

Finally got around pulling my inline check valve above the compressor out and checked it. You could blow in either side and the same amount of air came out. I have now ordered a new one from FOT. I tried to open it up last night but was unsuccessful in doing. I was trying with a crescent wrench and valve in vice and it was not giving. Even tried hitting end of wrench with hammer. Today going to take a socket with my almighty impact wrench and see what happens.

I also got a picture of what our filter /air dryer looks like. I am not sure how I would go about being able to get to it since it is crammed between the inverter and air compressor. I had a hard time just getting a picture of it.

Re: Air Leak--Check valve

Reply #23 – July 05, 2023, 11:37:57 am

TurboJack, I also tried to disassemble the check valve to look into the possibility of rebuilding it and there's no way I could get it apart. I can't even tell for sure that it's two pieces although it must be. Please update if you're able to get it apart. In your picture, that's the water separator with automatic drain solenoid on the bottom. Our older coaches have that as the first stage of water separation and then we have a dessicant bowl filled with beads that change from blue to pink when they've been exhausted. Do you not have a dessicant filter at all on your system?

Re: Air Leak--Check valve

Reply #24 – July 05, 2023, 12:39:39 pm

Quote from: Geodmann – July 05, 2023, 11:37:57 am

Do you not have a dessicant filter at all on your system?

No, that is all that we have.

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