Haldex / Midland Check Valve Rebuid Kit

Topic: Haldex / Midland Check Valve Rebuid Kit (Read 3145 times) previous topic - next topic

Haldex / Midland Check Valve Rebuid Kit

June 04, 2017, 05:44:40 am

I recently replaced the check valves (CVs) on the front and rear air tanks. I thought I'd try to revive the removed CVs with a rebuild kit. The first of 4 went fine. It had a little rust that cleaned up OK. Installed the new spring, seat and o-ring. Note that the spring is a little heavier gauge than the original. Photos 1-5.

The remaining 3 were ruined by rust. Photos 6 and 7 typical.

If you open a solenoid and find bits of rust, your CVs might be a place to check.

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #1 – June 04, 2017, 06:51:05 am

If you want them to be squeaky clean soak them in vinegar for a few days. The one in the last two pictures may be too far gone to rebuild but you can try it.

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #2 – June 04, 2017, 07:32:59 am

Excellent investigative photo report! Good clear close-up photos - make it easy to see how the valve works.

What is the cost of rebuild kit versus a new valve?

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #3 – June 04, 2017, 07:55:14 am

I wonder what the inside of your tanks look like Mark?

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #4 – June 04, 2017, 09:30:10 am

CLR works great for rust also!

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #5 – June 04, 2017, 09:54:11 am

Quote from: Travelin' Man – June 04, 2017, 07:55:14 am

I wonder what the inside of your tanks look like Mark?

Me too...

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #6 – June 04, 2017, 09:56:35 am

Quote from: Chuck & Jeannie – June 04, 2017, 07:32:59 am

Excellent investigative photo report! Good clear close-up photos - make it easy to see how the valve works.

What is the cost of rebuild kit versus a new valve?

Local NAPA about $28. Rebuilt kit $18. Not really worth the time to do a lot with the old valves for a savings of $10 each, but it was cool to see how they worked. I have a couple of spare rebuild kits

if anyone wants one PM me.

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #7 – June 04, 2017, 10:10:43 am

Let's back up and look at the ROOT CAUSE of the rusty valves (and likely many more components of the air system):

The AIR DRYER had failed. The dryer is one of the more neglected service items on any DP. If you ever see water or, worse, white powder from the wet tank drain, the dryer has FAILED.

Get out your check book.

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #8 – June 04, 2017, 10:49:40 am

Wolfe, seems this is one of the most mentioned things on this Forum and should be at the top of the list (in my view) when buying a coach, "when was the last time it had been serviced/replaced"?
We have so much info on the damage it does to a LOT of parts in the system that are VERY sensitive to rust and dessicant and, the time and cost to replace/clean them that this DRYER is one of the most important issues on our coach's.
This thing is in control of so many items that it must rate as maybe the top servicable item on our rigs, and actually is one of the easiest to get to!! It's job is to make sure your brakes work, your levelling system, the suspension, and each of these have a miriad of valves and switches associated with them. Every 2 yrs in my view is when it should be removed and serviced ( any one of you can do it if you want to) and regular checking of drain valves for moisture is as you know one easy way to check for problems. Do all do it,NO.
Just taking out and replacing the "6 packs" because you never thought about this thing will cure you for good as some have found. It is not a nice easy job doing them and could be very expensive to say the least.
Forget about the latest update etc right now and go check the last time this Dryer was done or you may be stuck at the side of the road soon and while waiting for the Tow looking at the nice new LED lights or new upholstry that was more important than this Dryer.
Think about it- seriously!!
I do realise my comments may offend some and that is good, as this is a serious issue.
Marks coach is new to them so they are excused from this rant.
JohnH

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #9 – June 04, 2017, 11:22:54 am

Your rants are imformative.Are his check valves the same as the older coaches?
I wonder if alot of the moisture problems come from the aux. air compressor running with its not so great drier?

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #10 – June 04, 2017, 12:03:42 pm

JohnH, if you only have your air dryer serviced at Foretravel, you are eventually going to be on the side of the road. Why? Because Foretravel never changes the air dryer purge value when they service the air dryer. Why? Because they do not consider the purge valve to be a serviceable part. It is only to be replaced after it fails. Ask me how I know.

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #11 – June 04, 2017, 12:32:33 pm

I am a firm believer in factory (i.e. the factory that made the dryer) REMAN dryers. Valves, heater, etc are new, as well as filters.

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #12 – June 04, 2017, 12:37:27 pm

Quote from: John44 – June 04, 2017, 11:22:54 am

.............I wonder if a lot of the moisture problems come from the aux. air compressor running with its not so great drier?............

Quote from: wolfe10 – June 04, 2017, 10:10:43 am

Let's back up and look at the ROOT CAUSE of the rusty valves (and likely many more components of the air system):
The AIR DRYER had failed. The dryer is one of the more neglected service items on any DP. If you ever see water or, worse, white powder from the wet tank drain, the dryer has FAILED...................

John beat me to it while I was looking back at Mark's earlier posts.
In Mark's case, he discovered, during the PPI, that the previous owner (or the dealer) had pulled the fuse on the aux compressor rather than fix the cause of the aux compressor running too much (or maybe continuously). Then Mark found the aux. dryer system unuseable, from neglect, and replaced it with a superior system.

Brett's point is true and I agree whole heartedly that owner's neglect of the engine driven air dryer tower is the ROOT CAUSE of myriad air system problems.

But in Mark's case, the ROOT CAUSE of corrosion in the three forward tanks was equally or (in my opinion) much more likely due to the uncorrected air leaks which caused the aux air compressor to run to failure, which caused a large volume of air to be pumped which in turn exhausted the small air dryer desiccant system, which then pumped a lot of moisture into the aux tank which also wasn't serviced (drain tested periodically) which corroded the aux tank check valve which then spread the moisture to the front and rear reservoir tanks (and wet tank) all of which were also probably not serviced (drain tested periodically) which in turn rusted/corroded the front and rear tank check valves......AND who knows what else?

Brett and John H are absolutely right that improperly (or worse) unserviced air dryers are responsible for more grief and pocketbook/time drains than owners give them credit for. Don't leave the aux compressor air dryer out of your preventative maintenance routine, though. Because the aux. dryer is small (Mark has done well in improving his design and capacity) it needs to be serviced (at least inspected) several times more frequently than the main engine driven air system dryer tower, depending upon climate and the nature of any uncorrected leaks that you have.

And of course, using a small shop or home or coin operated compressor to air up anything on a coach, including tires, is begging for trouble. People say, "Aww, it's just this one time and I won't hurt anything". Well depending upon humidity and the mass of air pumped, it is probably more volume of water than you imagined. For example, with our coach tires, starting at atmospheric pressure and pumping up to a pressure of 100 psig, 72 degree F air at 70% humidity has over 1/3 cup of water in it. Much better to use known good air or nitrogen or (my preferred choice) a Power Tank, CO2 System. AND, I won't allow a tire shop to put their air in any of my tires, unless they are willing to show me their air dryer system. That's a whole 'nother story on what I have experienced when I made that demand! Usually it's just easier to tell them to only use my CO2, Power Tank. They don't grumble as much.

HTH,
Neal

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #13 – June 04, 2017, 01:18:11 pm

Quote from: Neal Pillsbury – June 04, 2017, 12:37:27 pm

...And of course, using a small shop or home or coin operated compressor to air up anything on a coach, including tires, is begging for trouble. People say, "Aww, it's just this one time and I won't hurt anything". Well depending upon humidity and the mass of air pumped, it is probably more volume of water than you imagined...

HTH,
Neal

Neal -- Glad you like the new drying system. I added an input port so I can use my shop compressor during leak checks and testing, but the input port is upstream of the new aux air drying system. Thus any air from the shop compressor should be nice and dry.

Quote from: wolfe10 – June 04, 2017, 12:32:33 pm

I am a firm believer in factory (i.e. the factory that made the dryer) REMAN dryers. Valves, heater, etc are new, as well as filters.

Brett -- Appreciate your input. I plan to replace the main Haldex dryer this week.

Mark

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #14 – June 04, 2017, 02:29:11 pm

I marked up the attachment to show what I suspect has been happening. The check valves in the diagram labeled CV1 - CV4 were all failed (the other 2 CVs on the front / rear tanks were also failed but don't matter for this scenario).

1. The solenoid valve that allows one to connect the aux compressor output to the wet tank input (shown as SV1 on the drawing) was failed in the open position.
2. Because (as Neal reminds us above) the factory aux air drying system had failed, whenever the aux compressor ran, wet air continually fed wet tank (path shown by the red arrow). This happened regardless of the switch position since the SV was failed open.
3. The wet air then followed the normal air path out of the wet tank (shown by the yellow arrows) to the front and rear tanks.
4. The blue arrows show the wet air exiting the front and rear tanks through the protection valves (both of which are interestingly enough working) through CV's 3 & 4 (normal path).
5. Because CV2 was failed, the wet air fed back into the aux compressor output circuit as shown by the purple arrows.

Over and over.

EDIT: Forgot to mention that the air regulator that controls the front airbag manifold pressure also failed with a large leak. Thus there was a constant demand aux air. That too has been remedied.

During the initial inspection the slide out air tank had a lot of water. 2 quarts or more. Since that initial draining, no more significant moisture has been observed during draining even during the drive from TX to GA and it rained pretty much that entire trip. The aux compressor was not used during that trip or since until the new drying system was installed.

As evidenced by the CV photos in the initial post above, I have the chunks of rust on the loose. I thought about protecting the 6-packs and the SO manifolds by installing filters at the three locations indicated. I'd actually install the filters inside the bay next to the new dryer system so I could monitor their condition. But this seems like a stop-gap measure since all the bits and pieces of the brake system would still be vulnerable to rust particles coming through the airlines.

Does it make sense to just replace the tanks?

Thoughts?

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #15 – June 04, 2017, 02:33:56 pm

Quote from: wolfe10 – June 04, 2017, 12:32:33 pm

I am a firm believer in factory (i.e. the factory that made the dryer) REMAN dryers. Valves, heater, etc are new, as well as filters.

I understand what you are saying but, and it is a big one "can you swear to me that ALL factory rebuilt Dryers are 100% correct? in other words was someone having a bad day while doing it and forgot/screwed up something in the rebuild/" Yes I know it is remote but I like to see it myself and know that I have done it right. Also it is good to know how/what they work like.
I forgot to mention the aux comp' as with no slides and me never using it (auto level has never been on) It m,ay as well not be there for me.
Draining the tanks every couple of days is worth gold.
JohnH

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #16 – June 04, 2017, 02:58:27 pm

Quote from: John Haygarth – June 04, 2017, 02:33:56 pm

I understand what you are saying but, and it is a big one "can you swear to me that ALL factory rebuilt Dryers are 100% correct?

JohnH

Nope, no guarantee of 100%. But substantially higher change of it being correct, than "Bubba" rebuilding with "made to replace" parts of dubious quality or "built to replace" the part number of equally dubious quality.

And, I totally agree, check the wet tank drains-- have always said they were the "report card" on dryer health.

And, yes, with an auxiliary compressor, there are two sources of moisture/contamination.

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #17 – June 04, 2017, 04:08:03 pm

If the tanks are ASME or DOT they may be expensive. Same size pipe with end caps welded by a certified welder meets ASME standards as does a pipe with removable victalic end caps. Add some thread o let's as required.

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #18 – June 04, 2017, 04:21:29 pm

Quote from: Old phart phred – June 04, 2017, 04:08:03 pm

If the tanks are ASME or DOT they may be expensive.

The tanks that fit most Unicoaches are reasonable.
Wet tank ~$125
Front & Rear tanks ~$75
Bladder seal tank ~$50

Pamela & Mike

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #19 – June 04, 2017, 04:33:04 pm

Quote from: Pamela & Mike – June 04, 2017, 04:21:29 pm

The tanks that fit most Unicoaches are reasonable.
Wet tank ~$125
Front & Rear tanks ~$75
Bladder seal tank ~$50

Pamela & Mike

That's way less than expected. Source?

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #20 – June 04, 2017, 04:39:14 pm

Quote from: Pamela & Mike – June 04, 2017, 04:21:29 pm

The tanks that fit most Unicoaches are reasonable.
Wet tank ~$125
Front & Rear tanks ~$75
Bladder seal tank ~$50

Pamela & Mike

My info shows JWP as the manufacturer.

On a 2003, front, rear, and wet tanks are all showing as 1239, a 12" X 15" Rev B tank. Hopefully P&M can verify since their pricing would indicate a different wet tank.

I'm showing 8001, an 8" x 32" tank, as the slide bladder tank.

These are the tanks only, not the assembly with the fittings.

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #21 – June 04, 2017, 04:44:50 pm

Quote from: Michelle – June 04, 2017, 04:39:14 pm

My info shows JWP as the manufacturer.

On a 2003, front, rear, and wet tanks are all showing as 1239, a 12" X 15" Rev B tank. Hopefully P&M can verify since their pricing would indicate a different wet tank.

I'm showing 8001, an 8" x 32" tank, as the slide bladder tank.

These are the tanks only, not the assembly with the fittings.

Michelle,

Thanks for the info on the tanks. Sounds about right. The wet, front and rear appear to be the same although I haven't measured them.

The outside of my tanks are in good enough shape to read the imprinted info. I'll look tomorrow and see if there's a model number. I do recall seeing "DOT" and "150 PSI" on them.

It's ironic that the outside of my tanks are rust free....

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #22 – June 04, 2017, 05:04:25 pm

Mark, not ironic the inside cannot dry off like the outside and air passing thru gives it perfect conditions.
JohnH

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #23 – June 04, 2017, 05:11:39 pm

We have a Truck parts world here. If someone swings by and needs one we just go out there and they match one up. (so I don't have a TPW part number) Any good truck shop should have at least a DOT air tank book that you can look a replacement up. These aren't special made for our application they are off the shelf items. If you want to get fancy they are even some made of stainless. The older coaches do have a larger wet tank than I have seen on the Nimbus though so always do a matchup for best results.

One other thought is you may want to get one with at least one extra boss for some use you may dream up.

Pamela & Mike

Re: Haldex / Midland Check Valve Rebuid Kit

Reply #24 – June 05, 2017, 08:02:42 am

I'd go one step further. Don't buy any coach unless the PO can prove the air dryer has been changed regularly-in my case every 18 months as the FT maintenance schedule specifies.

Affiliate Notice