Air Tank Refresh / Replacement

Topic: Air Tank Refresh / Replacement (Read 1291 times) previous topic - next topic

Air Tank Refresh / Replacement

March 06, 2025, 01:45:26 pm

Attached is what our tanks looked like. On our year coach there are (3) identical tanks, each with a unique set of valves & plumbing tree attached to them. The tanks were stamped JWP (Johnson Welding Products) A-9122. I believe these were used on 1990 through 2005 coaches, 2-3 on each.

Our leak down rate was excessive, full to nothing in approx an hour. We also had a longer than "normal" pressure up time, it would gain up to the 105psi and then take a bit to finally "pop off" at 125psi.

The leaks appear to all before the air bags / HWH manifold as we can fully raise the coach and it will remain there for weeks with little to no lowering. The air bags had been replaced in the last couple of years.

Deciding that replacing all of the components; single check valves, double (shuttle) check valves and pressure protection valves would be good PM as they all are 25yr old originals. I also felt that removing the tanks would be the easy way to get that done as I also wanted to clean the rust off the tanks, give them a good inspection for leaks, and then paint them.

All of the valves on the tanks were Meritor WABCO parts and I cross referenced them to Haldex part numbers (Part Number Collection). I was able to find most of these on Ebay in the $20-25 price range, search on all of the part numbers as NOS will show up. There are rebuild kits available but I was not sure a Haldex rebuilt would work in the original part, plus those rebuild kits were in the same price range I was finding NOS on Ebay.

Looking at the tanks and thinking about the effort to de-rust, de-scale and paint vs the cost of new tanks, we began to investigate getting new tanks. More on that adventure next.

Re: Air Tank Refresh

Reply #1 – March 06, 2025, 02:41:22 pm

So if the tanks are leaking at pin holes they are at end of life. If they have corroded threw in one spot that same tank will have other points about to fail also. Removing any component can prove to be impossible to do and may be reason to replace the tank but that being said everything can be removed by someone with the proper technique although the component will need to be replaced. Probably should have automatic drains installed on all of our tanks. My shop air compressor would get drained daily and I would get moisture out of it daily. Went to an automatic drain that drains every 45 minutes of being powered up and drains tank for 2 seconds. Now when I test it I never see any signs of moisture in the tank. I regret not doing it years ago. My take on the tanks they are either good or bad. When we got our coach I drained about half of the slide bladder tank of water. Point being stay up on your water separator system on your Aux compressor. I added a desiccant dryer on mine. Auto drain may have the same results? Toss those original drain valves. They are probably part of your leaks also

Re: Air Tank Refresh

Reply #2 – March 06, 2025, 06:16:09 pm

I replaced the rear tank on my 91 and it looks the same as your tanks. I was unable to find a direct replacement, so I ended up with something that was close and would fit in the space. I ended up with a larger tank. Let me know if you find a direct replacement.

https://www.fleetpride.com/parts/power-products-2850-in-3-capacity-12-diameter-trailer-air-tank/01tUZ000001qUZ3YAM

This is what I ended up fitting in the rear. Front fit up would be much easier.

Re: Air Tank Refresh

Reply #3 – March 06, 2025, 06:39:15 pm

Quote from: kgrover – March 06, 2025, 06:16:09 pm

I replaced the rear tank on my 91 and it looks the same as your tanks. I was unable to find a direct replacement, so I ended up with something that was close and would fit in the space. I ended up with a larger tank. Let me know if you find a direct replacement.

It will be in one of the future installments

Re: Air Tank Refresh

Reply #4 – March 06, 2025, 07:47:14 pm

My rear tank looked like that and I used a disk grinder with a wire brush to clean the rust off of the tank and then painted it.
You need to find the leak or leaks.

Re: Air Tank Refresh

Reply #5 – March 06, 2025, 10:00:48 pm

The rust on that tank looks very superficial. Also interesting that the rust is on the bottom only of the suspension sub frame tubing. I've never seen that before. I guess I'm really fortunate that my coach has little or no corrosion underneath. I have other problems to make up for my good luck though... lol
I would prep and paint those tanks... just my opinion. I definitely enjoy watching your adventure.

Re: Air Tank Refresh

Reply #6 – March 07, 2025, 10:19:18 am

They have good rust coverage, not just surface but raised areas that you can flake off. I would not be surprised to find a pin hole leak but then again those tanks are pretty thick/robust as well.

The rust on the sub-frame is just superficial. This coach was kept inside during the winter, but I suspect it was over a dirt or gravel floor in a barn, damp and cold. It would also explain why I had to remove several nests of everyone's favorite snack stealing friends the rodents.

The tank drains, well everything on them, will be updated. Right now only the wet tank has a remote drain so its easy to check. In the future I would like to do the same for the two front tanks, our 03 was set up like that and it made it easy to check on them. Even a pull chain style would be an improvement.

All the tank fittings used pipe dope, so they may require a little local heat to soften the dope and break loose, I'm sure they will come out ... with the exception of the internal hex brass plug at base of the tank.. With new replacement tanks I'd simply get new "everything" and start of clean. I'd salvage what I could from old tanks for the parts bin.

Re: Air Tank Refresh

Reply #7 – March 07, 2025, 10:36:29 am

Another way would be to pressurize the tanks to 150 psi. and use a dish soap and water mixture to see if there are any leaks, then paint with black epoxy paint if they don't leak.

Re: Air Tank Refresh / Replacement

Reply #8 – March 10, 2025, 06:29:41 pm

Getting new tanks

A call to FT parts and the tanks are no longer available, but they do have a replacement they are using. That replacement is an Automann 172.2001D (?) which is a universal tank, NOT a drop in replacement. They were clear that it had the right tank fittings, but it needed some effort to update the way things were mounted and possibly some new air lines.

The original tanks are 15" long and 12" in diameter with top-mounted brackets. The universal is 22.5" long and 9.5" in diameter with side ear brackets. They hold approx the same volume of air, within 100cu-in. Installing those replacement tanks would take some effort, some existing air lines will not reach, and you need to fabricate mounting brackets for the coach. That is after you determine a place/orientation where they will fit.

Not wanting to go that route, we started calling around to salvage yards and doing searches for air tanks "close" to what we had. All the salvage yards turned up empty and finding a cross tank was not yielding great results, either via the web or our local truck parts store. There were a couple of Freightliner tanks that looked close (a little lower air volume), but those needed to have brackets fabricated and welded on (they were simply raw tanks). Perhaps others have had better luck in sourcing somewhat "drop-in" replacements.

The tanks on our coach were stamped Midwest Products Inc, 06-16-9, very difficult to read due to the rust and could only be seen on (1) one tank. Foretravel stopped using Midwest Products (2000-2002?) and began to use tanks made by Johnson Welding Products (JWP) P/N A-9122. Same exact tank, just a new vendor and P/N. We contacted Johnson Welding Products (JWP) to inquire about availability or even special ordering them. Unfortunately, JWP did not respond to emails or phone calls, even to simply say sorry bubba, yer outta luck.

In researching JWP, Michelle discovered they had recently been sold/acquired by Tramec. We contacted Tramec. They were very quick to respond and apologized that JWP was unresponsive. They indicated that the change over was still a work in progress, but they would check with JWP on the availability of the tanks. It took a couple of weeks and some back and forth with Tramec (Darcy Brady/Customer Service) but we eventually were put in contact with Brook Hessey, the Territory Manager for our area of the country.

Brook called us, got all the information on the tanks, and had his inside team dig into what was going on. Within a few days, he contacted us again and said that indeed those tanks were no longer being produced, but they would fabricate them for us as a sort of apology for JWP's lack of responsiveness

. The only downside was that these would be raw tanks, no brackets.

We contacted several fabrication shops in the area that could make brackets, and we made contact with a certified tank welder. Most regular welders did not want to take on the liability of working on air (brake) tanks. Can't say I blame them. We contacted Brook and asked for bracket prints and let him know we had found fabricators & welders to do the work. A few days later he called and said they would make the complete tanks, brackets and all, perhaps a liability concern with having us getting that work done.

To order the parts, we had to go through Fleet products and place a special order. Brook put us in contact with the right person and did all the prep work so we could easily place the order. The price came to $250 a tank ... that is tank, tax, crating and truck shipped to our house. FT wanted $220 for the Automan tanks (plus tax and shipping), just for perspective. I know you can get those Automan tanks in the $150 range, plus tax, plus shipping, plus bracket fabrication, plus some new air lines, plus creative process aggravation, etc.

It did take a couple of months for the order to be fulfilled, fortunately we were in no rush to go anywhere during Nov/Dec and had plenty of other coach projects to keep us busy while we waited. Little things like actually getting it running again

Both Brook and Darcy were great to work with and were very responsive. We did ask if we could let folks know the tanks were again available, but Brook said this was a one-off build and that they would not be offering these or building them again. We asked a few times for them to keep the P/N active to no avail. However, if you were in need of tanks, I'd surely give them a call. You never know. I'm sure if there was a large order they would consider it.

Re: Air Tank Refresh / Replacement

Reply #9 – March 10, 2025, 08:51:44 pm

The Tramec-Sloan e-mail I sent that resulted in our first responded-to note to was

customerservice@tramec.com

Darcy responded within 24 hours. Her signature indicated "Darcy Brady, Customer Service, Tramec Sloan / Fleet Engineers Products". Her manager is the one who had Brook Hessey contact us directly.

If you use this link, put in Country and then select State or Province, and click "Submit", your territory manager's contact info will come up

Contact Us

Brook Hessey handles:

Market: Aftermarket/Fleet
Territory: FL, GA, AL, MS, SC, NC, TN

If you're in one of those states, you can try pinging Brook. If you're in another state, you'll have a different territory manager (but you might let them know of this successful interaction

)

ETA - here's the relevant text of the note I sent to the Tramec customer service e-mail:

Quote

"Good afternoon,

I have a Foretravel motorhome that is equipped with Johnson Welding Products air reservoirs/tanks for air braking. Foretravel no longer stocks these tanks and I have been unsuccessful at locating any online vendors who carry these shorter air tanks.

I am reaching out to Tramec, as owners of JWP, in hopes of sourcing replacements for these tanks.

There are 3 tanks total, all the same size and configuration. They were used throughout Foretravel's production in the 1990's and 2000's and there are still many of these motorhomes on the road today.

The tanks are 12" diameter, roughly 15" long. Top mounted. The tank configuration is 3 ports on one side, 1/2, 1/2, 1/4 I believe, then 1/2 ports on the two end bells and the 1/4 drain.

The most recent version of the tanks we have seen were stamped JWP and "A-9122".

I would appreciate any information on sources where I might purchase these tanks.

Thank you,"

Re: Air Tank Refresh / Replacement

Reply #10 – March 11, 2025, 06:01:14 am

Maybe someone could organize a group buy, similar to the work done for the hydraulic pumps a while back. If you can get enough interest, they might be willing to do a run for a high enough quantity. Those new tanks sure to look nice.

Re: Air Tank Refresh / Replacement

Reply #11 – March 11, 2025, 11:35:35 am

I doubt that many people would change tanks as a precautionary measure. My tanks on the '81 FTX still don't leak and I never lost a tank on any of my trucks or cranes. I actually have a spare as a member many years back bought 3 new tanks because of the white powder issue and he didn't think they could be cleaned enough to use so I bought one and put it on one of my spares shelves. If I ever need it I will have it hot tanked then I will repaint it.

Re: Air Tank Refresh / Replacement

Reply #12 – March 12, 2025, 10:29:21 am

Quote from: craneman – March 11, 2025, 11:35:35 am

I doubt that many people would change tanks as a precautionary measure

I'm sure it falls under the change them when (and if) they fail category, like the D2 or Air Dryer. Not like you are going to travel around with spare air tanks.

In my case I felt they were bad enough that I did not want the risk, they had lived on a northern high salt diet. Having original tanks makes the change a lot less involved and certainly in the DIY area. If you had to use different shaped tanks that mounted and plumbed differently it gets more involved, and if you can't do it yourself, it will rack up an impressive shop bill.

Re: Air Tank Refresh / Replacement

Reply #13 – May 12, 2025, 09:21:10 pm

I wanted to take a minute to document the final tank swap-out process.

I started by disconnecting all the air lines from the tanks. Our setup uses D.O.T. compression fittings rather than push-to-connect types. As I removed each line, I marked its number directly on the corresponding tank fitting—this made reassembly much easier. Make sure you have your safety blocks in place before starting.

Once all the air lines were disconnected, I removed the tanks. The two front tanks are secured with nuts and washers. I'd sprayed everything with Liquid Wrench the day before, and all fasteners came loose easily. The mounting studs are actually Roloks driven down through brackets that are themselves fastened to the frame.

The rear tank (the wet tank) is mounted differently. It uses four Roloks driven upward—two into a sheet metal bracket and two directly into the frame rail. I was concerned the frame rail bolts might snap, as they wouldn't budge with a socket wrench, but they came out easily with an impact driver (start on a low setting).

The tanks aren't particularly heavy. I supported them with a mix of blocks, jacks, and anything else that would fit underneath. From there, I slid them out from under the coach—plenty of clearance.

New Fittings

Once the tanks were on the bench, I started removing the old fittings—but quickly decided it was easier to replace them. We took the old tanks to a local truck repair shop, where they matched the fittings one by one. The owner even lent me his set of Snap-on Weatherhead fitting sockets, telling me I'd need them more than he did—just to return them when finished. Turns out those were his late father's tools. Great folks at J&K Truck Repair, and yes, they will work on motorhomes.

Reassembly

With the new fittings in hand, I began assembling everything. I used Loctite 565 on the pipe threads and installed each fitting carefully, matching the orientation to the original setup. Pay close attention to the flow direction arrows on the pressure protection valves—you definitely don't want to install them backwards.

I did eventually remove and clean the old fittings as well. They'll be good stock for future projects.

With the fittings installed, I reversed the removal process: slid the tanks back under the coach, lifted them into place, and fastened them. I did the front tank and its air lines first, then moved to the rear tank.

Many of the air lines were just long enough, so I reused the existing ferrules and tubing on several. In some places, I trimmed the lines and installed new ferrules. When reusing, the original tube stiffeners (the inserts that make them DOT-compliant) were usually still inside the tubing. I used side cutters to gently work them out—just apply light pressure between the stiffener and the tube end and they'll slide out easily. The new fittings had built-in stiffeners.

To reconnect the lines, I fully seated the tube and ferrule into each connector, hand-tightened the nuts, and then used a wrench to snug them—just a couple flats. After everything was buttoned up, I had two very minor leaks that went away after a couple of loosen/tighten cycles.

What's That Noise?

One issue we ran into was a strange noise from the new Haldex KN23000 check valves. In our configuration, the wet tank's "out" line runs to a tee, and each side of the tee feeds a tank inlet via one of these check valves. One of these check valves is also used on the "in" to the wet tank. During tank filling / cycling, they made a pronounced groaning/honking sound. The selected media item is not currently available.

OK that is not the actual sound, but its pretty close to what you would hear inside the coach.

Here's a video that explains the issue:
https://www.youtube.com/watch?v=cyVqyx8_4Xo

After discussing with James Johnson at MOT—who was very familiar with the issue, the fix was to replace the Haldex KN23000 valves with Bendix SC3 / 800372 units. Whether you experience this problem will depend on your air line layout which varies by model year, etc. With the Bendix valves installed, the flutter noise disappeared.

One Last Item

After the install, there was still a noticeable air leak when the tanks were full. You could hear it briefly after shutting down the coach. Tracing it back, I found the pressure regulator feeding the HWH front 6-pack was leaking from the stem.

This regulator should be set to 65 psi, but ours was set around 105 psi—which should have been a red flag.

I grabbed a replacement from Lowe's, installed it the same way as the old one, and... it leaked even worse. After staring at it for a bit, I realized it was installed backwards, the outlet was facing the tank instead of the 6-pack. I checked photos taken before disassembly, and sure enough, the old regulator had also been installed backward. I'd copied the mistake.

I'd set the new regulator to 65 psi, which made the leak even more noticeable. The backward installation explains why the previous one was set so high—it had to be cranked up to delay leaking. With the tank pressure at 125 psi, it would immediately bleed down to 105–110 psi.

This helped explained our slow pressure build at idle between 100 and 125 psi.

Final Notes

With everything complete, we're now seeing less than 1 psi per hour of leak-down at the tanks—a massive improvement. I still suspect a small leak at the step cover valve, so that's on the list. Maybe not next, but it's coming.

Re: Air Tank Refresh / Replacement

Reply #14 – May 13, 2025, 11:29:14 am

I can relate to the noisy check valves. My air system made some tell tale groaning noises before and I completely replaced all of the valves and fittings at my air tanks similar to what you did except I didn't need to replace my tanks. I was hoping to eliminate the noise problems. Instead to my dismay with all new components, my air system now makes more noise than it did before. There are all kinds of groaning and moaning noises. I will probably just tolerate it and move on to bigger problems. It does sort of tell me what the air system is doing once I figure out under what conditions they occur.
I see you're using a lot of new brass bar stock fittings. I've found these harder to come by as many suppliers have switch to forged fittings. What was your source for those?

Re: Air Tank Refresh / Replacement

Reply #15 – May 15, 2025, 09:48:33 pm

Quote from: Geodmann – May 13, 2025, 11:29:14 am

I see you're using a lot of new brass bar stock fittings. I've found these harder to come by as many suppliers have switch to forged fittings. What was your source for those?

That is what my local truck repair shop had, all pulled from their fittings cabinet.

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Air Tank Refresh / Replacement

March 06, 2025, 01:45:26 pm

Re: Air Tank Refresh

Reply #1 – March 06, 2025, 02:41:22 pm

Re: Air Tank Refresh

Reply #2 – March 06, 2025, 06:16:09 pm

Re: Air Tank Refresh

Reply #3 – March 06, 2025, 06:39:15 pm

Re: Air Tank Refresh

Reply #4 – March 06, 2025, 07:47:14 pm

Re: Air Tank Refresh

Reply #5 – March 06, 2025, 10:00:48 pm

Re: Air Tank Refresh

Reply #6 – March 07, 2025, 10:19:18 am

Re: Air Tank Refresh

Reply #7 – March 07, 2025, 10:36:29 am

Re: Air Tank Refresh / Replacement

Reply #8 – March 10, 2025, 06:29:41 pm

Re: Air Tank Refresh / Replacement

Reply #9 – March 10, 2025, 08:51:44 pm

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Reply #10 – March 11, 2025, 06:01:14 am

Re: Air Tank Refresh / Replacement

Reply #11 – March 11, 2025, 11:35:35 am

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Reply #12 – March 12, 2025, 10:29:21 am

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Reply #13 – May 12, 2025, 09:21:10 pm

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Reply #14 – May 13, 2025, 11:29:14 am

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Reply #15 – May 15, 2025, 09:48:33 pm

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