Can't build air, not the D2 governor

Topic: Can't build air, not the D2 governor (Read 4570 times) previous topic - next topic

Re: Can't build air, not the D2 governor

Reply #25 – November 14, 2020, 05:30:16 am

We chased this issue down my coach in the spring. We did it is steps trying to find the problem... replaced the D2, no improvement. serviced the air dryer, slight improvement. Eventually replaced the engine compressor, which fixed the issue.

Re: Can't build air, not the D2 governor

Reply #26 – November 14, 2020, 07:16:27 am

Quote from: Don & Tys – November 13, 2020, 10:27:30 pm

1. I have a new PURest air dryer that says it isn't compatible with Holset compressors. Without the isolation valve,
2. I don't think the OEM "Pure Air Plus" is either.
3. My thinking that the addition of an isolation valve would do the same thing for the PURest that I have on hand... Any thoughts?
4. I would consider that Turbo 2000 with the QE compatible configuration mentioned at the end of the short video I posted, but sounds like it might be pricy.

Don,

1. Correct, it will work somewhat but not properly
2. Correct
3. You are on a role, with out the isolation valve you will run the risk of pumping oil and this will cause carbon build up in the compressor and or unloader rendering your wallet grief.
4. About $450 (the last time I checked) this is made more like the AD-9 dryers in they are a lot easer to change out elements and clean the inner works. The replacement cartridge is about $50. The unloader and service kits are about $100 for both together (not each). So if you have an old style Pure air plus and need to service it, then replacing it with one of the Turbo 2000 (not to be confused with the turbo turd 3000) isn't that much more.

Mike

Re: Can't build air, not the D2 governor

Reply #27 – November 14, 2020, 12:59:27 pm

Don, we have the Pure Air Dryer but no Isolation Valve and it works fine.
Johnh

Re: Can't build air, not the D2 governor

Reply #28 – November 14, 2020, 01:33:15 pm

You have a different compressor (Wabco?) that doesn't need it. I think the 2000 model year is when that changed for the ISC powered coaches. Lucky you!

Don
Here is another video that sheds some light on the Cummins/Holset compressor/Air Dryer compatibility requirements.
http://youtu.be/EAZJuaX1xNM

Quote from: John Haygarth – November 14, 2020, 12:59:27 pm

Don, we have the Pure Air Dryer but no Isolation Valve and it works fine.
Johnh

Re: Can't build air, not the D2 governor

Reply #29 – November 16, 2020, 03:00:40 pm

I have ordered an SKF Air dryer from Find it Parts.
620500 by SKF - Air Dryer Parts
There are several versions of this unit. The ones for Holset compressors have SKF part numbers that start with 620 and end in the 500's, i.e.; SKF 620500 Assy with bracket and external purge tank and various installing bits. Part number SKF 620502 is the dryer itself (and maybe the mounting bracket). SKF part numbers that end in the 600's (i.e.; SKF 620602 is the dryer unit only without the internal plumbing that the Holset compressor's need to keep the pump from passing oil. In my opinion, the Isolation valve required for the Holset compressor used with Pure Air Plus 3-line dryers used on the 1st year of the ISC's production is a is a band aid to make up for a design flaw.
Here is text from SKF's website that describes the model number nomenclature;

Quote

Turbo-2000 comes in two distinct variations. The 500 (ie: 620500) series is designed for Holset E-Type compressors. E-Type compressors have special plumbing considerations that the E-type compatible SKF air dryers contain. The Holset E-Type compressors are mainly found on Cummins engines and some Mack but have not been an OE option for several years. The 600 (ie: 620600) series should be used on all other compressors.

Since I hate the location of the OEM Haldex Pure Air Plus, the narrower profile of the SKF unit will allow me to make the air dryer much easier to service as well as simplifying the plumbing a bit. I am hoping to get it by Friday and will figure out the mounting details then. In the mean time, I am going to temporarily mount the Haldex PURest air dryer so I can diagnose the compressor issue, which due to the intermittent nature, is likely a stuck unloader valve.
Don

Re: Can't build air, not the D2 governor

Reply #30 – November 16, 2020, 04:42:18 pm

Quote from: Don & Tys – November 16, 2020, 03:00:40 pm

In my opinion, the Isolation valve required for the Holset compressor used with Pure Air Plus 3-line dryers used on the 1st year of the ISC's production is a is a band aid to make up for a design flaw.

Don

What gave it away? Maybe the "We need to keep the compressor under pressure or it pumps oil."?

Re: Can't build air, not the D2 governor

Reply #31 – November 16, 2020, 06:46:13 pm

I recently went through the same problem of suddenly not being able to build air. Cummins has a procedure to try and free up the unloaded valves in the compressor head. Since there is no external access to the valves without draining antifreeze and removing it. They suggest removing both the air intake hose and the main discharge line and spraying a Liberal amount of wd40 or penetrating oil into both openings and let it sit for an hour.I would run it prior to at least warm it up . After it sits ,start it up with lines off to let the yuck blow out. Carbon build up on the unloaded valves is a known problem, not so much on older non emissions engines. Tapping on the head with a hammer can help the loosening process. Reconnect the lines and hope for the best. The heads are available rebuilt or kits are available to do it yourself.
I saw you bypassed the Air dryer which is usually the most common problem of little or no air. You might want to rebuild the dryer while your in there if it hasn't been done in the last 2 years.

Re: Can't build air, not the D2 governor

Reply #32 – November 21, 2020, 11:19:04 am

I received the SKF Turbo 2000 on Thursday after ordering it on Monday... excellent service from Find It Parts! The sales rep took the trouble to call SKF to check that parts shown in the picture on Find It Parts' website were all included on the part number I ordered. I reused the heavy duty bracket Foretravel made but hung it from the heavy frame that the motor mount carriage is attached to. The Foretravel made bracket, was sitting on the crossmember that supports the rear engine mount, is like a large piece of ¼" thick angle iron with a triangular gusset bracing added. Hanging it from the frame rail changed the orientation 180º. Since the SKF unit comes with a bracket that orients the I/O ports a 180º from the way the OEM Haldex Pure Air Plus was mounted, that worked out perfectly. After determining the exact position the bracket needed to be in, I drilled and tapped holes for ⅜-16 bolts which I screwed in from the back, making them in function as studs, That makes removing and installing the SKF unit much easier to install since I can just hang it from the studs. It opens up the area a bit and the the whole SKF unit (or just the spin on canister can be removed from behind instead of having to go underneath or removing anything else. Access to the D2 governor plumbing connections to the air dryer is improved considerably because the smaller overall diameter of the SKF unit VS the Haldex gives increased clearance from the engine. I have successfully got the unloader valve unstuck to prove that the compressor itself functions as normal, but it stuck again. Today I will undo the air intake for the compressor and WD40 the heck out of it from above.
Does anyone know whether or not coolant runs through the unloader valve housing? I don't see why it would be, but if so, I would rather remove and rebuild or replace the unloader assy when I am going to change the coolant anyway.
Just looking at the videos linked above again, I don't see any coolant passages in the unloader housing, so it appears the answer is no...
Don

Re: Can't build air, not the D2 governor

Reply #33 – November 21, 2020, 08:08:52 pm

Quote from: Don & Tys – November 21, 2020, 11:19:04 am

Does anyone know whether or not coolant runs through the unloader valve housing?
Just looking at the videos linked above again, I don't see any coolant passages in the unloader housing, so it appears the answer is no...

Don,

You are correct there is no coolant in the unloader housing.

Mike

Re: Can't build air, not the D2 governor

Reply #34 – November 21, 2020, 10:16:35 pm

Confusing to me.. I ordered a new air drier this week from Truck Pro Truck parts. Called FT To see what air drier was put on my 96 8.3 new and I gave Truck Pro the information standing in my shop .. I can't get myself in position to look for a tag on the old air drier because of where it's mounted and my young mechanic wasn't here. Replacing it for PM purposes as it doesn't look like it's ever been changed. This post leaves me with having "compatible" questions before I even get the new drier. Truck pro ordered drier based on what parts dept at FT told me.Seems 3 line vs 4 line is the difference. Without a clear answer I suppose if my old drier is 3 line and I replace with a 3 line it should be compatible.... yes or not necessarily??

Re: Can't build air, not the D2 governor

Reply #35 – November 21, 2020, 10:35:35 pm

Dub,

The safest way to purchase a new or rebuilt dryer is to remove the old one and take it to a NAPA store. Lay it on the counter and say "I need the exact replacement for this thing". 9 out of 10 times they will have in stock, or can order, exactly what you need.

Since you have already ordered a dryer, you might as well wait until it shows up. Compare it to the old one that you or your mechanic removes from your coach, and see if they match up. If not, either exchange it for the correct one, or get a refund and go to NAPA.

Re: Can't build air, not the D2 governor

Reply #36 – November 21, 2020, 11:06:57 pm

That's what I aim to do Chuck..Would think it would be fairly straight forward on a 96 Cummins air system.

Re: Can't build air, not the D2 governor

Reply #37 – November 23, 2020, 01:58:56 am

The SKF Turbo 2000 comes with a remote mounted purge tank. It is basically a ping tank. They have a Turbo 3000 model that ia self contained and that would have been fine, but the price difference is minimal and the extra work of finding a place for the ping tank isn't a big deal, but the larger capacity of the Turbo 2000 (also available in a dual HC version) seems like it might be worth having. Today I mounted the ping tank alongside the chassis battery next to the bottom of the radiator. I reused the Haldex Pure Air Plus mounting bracket by shorting the clamp band by cutting it in half and overlapping it and drilling a hole through the overlapped pieces. I then countersunk a flat head screw through the tank side of the bracket to pin the two halves of the band clamp in place, I attached a scrap piece of ⅛" 2" X2" about 20" long angle iron to the chassis battery supporting frame to make a ledge for the tank mount. Just to be safe, I will add a hanger of some kind to the radiator support bracket to secure the other side.

I also removed and inspected the unloader valve. I will make another post about that...
Some more pictures of the air dryer mount and its location opposite the Holset air brake compressor as will as the purge (ping) tank.
Don

Re: Can't build air, not the D2 governor

Reply #38 – November 23, 2020, 08:04:55 am

Quote from: Don & Tys – November 23, 2020, 01:58:56 am

The SKF Turbo 2000 comes with a remote mounted purge tank. It is basically a ping tank.

I'm not clear about the purpose/function of the "ping" tank.

Re: Can't build air, not the D2 governor

Reply #39 – November 23, 2020, 08:56:40 am

Quote from: Chuck & Jeannie – November 23, 2020, 08:04:55 am

I'm not clear about the purpose/function of the "ping" tank.

It's a local tank used to deliver brief bursts of air faster than what can be delivered by the supply line.

Re: Can't build air, not the D2 governor

Reply #40 – November 23, 2020, 09:00:09 am

Quote from: Old Toolmaker – November 23, 2020, 08:56:40 am

It's a local tank used to deliver brief bursts of air faster than what can be delivered by the supply line.

OK, but why does Don's air dryer require a ping tank. The air pressure used to purge the dryer is usually contained within the air dryer housing. Other air dryers work fine without a external pressure tank.

Perhaps because this dryer has a smaller, slimmer housing it does not contain sufficient volume of pressurized air to facilitate a effective purge?

Re: Can't build air, not the D2 governor

Reply #41 – November 23, 2020, 11:17:08 am

The Turbo 3000 unit in which the purge air volume is included within the cartridge is listed as suitable for light to medium duty applications. The purge tank stores clean, dry air for regeneration of the desiccant bed. The self cotained Turbo 3000 would be adequate based on the Holset air compressor in our coach of around 12 CFM and normal use, but the greater purge volume of the separate tank provides extended compressor cycles which can only be a good thing. Since the price difference is minimal (and who's afraid of a little extra work

), I decided with the higher capacity. Below is a screen shot from SKF showing the vocational matrix (why not call it an application guide?).
Don

Quote from: Chuck & Jeannie – November 23, 2020, 09:00:09 am

OK, but why does Don's air dryer require a ping tank. The air pressure used to purge the dryer is usually contained within the air dryer housing. Other air dryers work fine without a external pressure tank.

Perhaps because this dryer has a smaller, slimmer housing it does not contain sufficient volume of pressurized air to facilitate a effective purge?

Re: Can't build air, not the D2 governor

Reply #42 – November 23, 2020, 01:29:56 pm

A size and form factor comparison of the Haldex dryers VS the SKF, plus a few pictures of the D2 Unloader ASSY combo,,,
Assuming we can make it to Quartzsite this time, I can bring the OEM Pure Air Plus to give away at the raffle...

It should be a good science experiment and I suspect it is rebuildable.
Don

Re: Can't build air, not the D2 governor

Reply #43 – November 23, 2020, 06:03:32 pm

OK so after all of this, Is it fixed?

Re: Can't build air, not the D2 governor

Reply #44 – November 23, 2020, 06:16:47 pm

What's the rush?

No, I am waiting for a rebuild kit for the unloader. Ridiculosly expensive for what is included. $102 shipped for this: 3559568K by HALDEX - Compressor Repair Kit

Aside from that, I will be replacing the protection valve, 2 check valves, adding a service air at the rear, and hopefully rebuilding the 6 packs...
P.S. I am posting the pictures and my conclusions etc., because I am learning more about the air system and want to share with someone down the line. Maybe it will help someone as pictures, part numbers, proceedures, etc. others have posted have been a big help to me for other projects, and I will be more likely to remember what I did.
Don

Quote from: Roger & Susan in Home2 – November 23, 2020, 06:03:32 pm

OK so after all of this, Is it fixed?

Re: Can't build air, not the D2 governor

Reply #45 – November 24, 2020, 11:00:32 am

Quote from: Don & Tys – November 23, 2020, 11:17:08 am

Below is a screen shot from SKF showing the vocational matrix (why not call it an application guide?).
Don

Because when you've spent $160,000 on a PhD . . .

" . . . a rebuild kit for the unloader. Ridiculously expensive for what is included. $102 shipped for this: 3559568K by HALDEX - Compressor Repair Kit."

Hydromat in Missouri builds a nice rotary transfer machine and we used to pay those prices for pretty much the same amount of stuff. It's what happens with limited production machinery.

Re: Can't build air, not the D2 governor

Reply #46 – November 24, 2020, 12:25:04 pm

Don, to Roger's question am I correct that in essence it is fixed after you took off the unloader valve body and cleaned the carbon etc off. You did mention that it worked but stuck again. The new dryer etc is just more refining of the system which you are good at and enjoy doing.
So, if anyone else has a similar problem with lack of air build up there is a real chance it can be fixed by taking that off and cleaning.
Johnh

Re: Can't build air, not the D2 governor

Reply #47 – November 24, 2020, 01:35:33 pm

John,
I have yet to reinstall the unloader ASSY as the gasket was trashed. Not easy to clean the gasket remnants off the compressor flange while the compressor is still on the coach. It would have been a whole lot easier if I had access to a pit!

. The rebuild kit is supposed to arrive tomorrow. But since I had managed to get air to build twice with normal function, I am confident that reinstalling the unloader valve will restore normal function. However, you are correct, I am upgrading the system with the new SKF Turbo 2000 dryer as well as taking care of other air system maintenance while I have it up on the ramps. I had apparently two major issues with the system as the air dryer had failed as well. The OEM Pure Air Plus was rebuilt (supposedly!) in Canada, but always had issues in that the wet tank would always leak down rapidly to about 30 PSI after cut off was reached. That resulted in rapid cycling even with the engine idling and no use of the brakes, but allowed normal operation while driving the coach. It has bugged me ever since because I don't like anomalous behavior. The air dryer failure this time resulted in the wet tank not being able to hold air at all. I diagnosed this by adding air directly into the wet tank via the service air supply with my trusty harbor freight compressor. It wouldn't hold air until I bypassed the dryer. With the bypass in place, I was able put a 120 psi in with the external compressor. Not only that, after sitting all night the wet tank was still holding air at around 115 psi! So my conclusion is that my suspicion of the hack rebuild job of the OEM dryer in Canada being the cause for the rapid cycling is correct. I look forward to once again having a (relatively) air tight system again. Replacing the check valves, rebuilding the 6-packs, replacing the protection valve, is something I have been wanting to do for a long time. I will be installing the check valves on the brake tanks using stainless unions so that (as you well know!) the entire plumbing tree won't have to be disassembled to get at the check valves, regulators, etc.
Don
Don

Quote from: John Haygarth – November 24, 2020, 12:25:04 pm

Don, to Roger's question am I correct that in essence it is fixed after you took off the unloader valve body and cleaned the carbon etc off. You did mention that it worked but stuck again. The new dryer etc is just more refining of the system which you are good at and enjoy doing.
So, if anyone else has a similar problem with lack of air build up there is a real chance it can be fixed by taking that off and cleaning.
Johnh

Re: Can't build air, not the D2 governor

Reply #48 – November 24, 2020, 08:22:32 pm

Don, on the dryer leak down problem it sounds to me that it may be the same issue I had after FT rebuilt mine about 2 yrs after I bought coach, and my first trip to the mothership. The little check valve in the end of the main line at dryer was put in backwards so leaked back. Since my air tanks hold really good after fixing numerous little leaks a few years ago and doing the 6 packs. One holds 110 for a week and the other has a very small leak below brake pedal. Tough to get to tighten those line fittings. It still takes about 4 days to leak down to 30lbs.
JohnH

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