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Topic: Air dryer rebuild (Read 1283 times) previous topic - next topic

Air dryer rebuild

Howdy folks, starting another project that I'm not looking forward to but is one of them many necessary evils of owning one of these. I believe the dryer itself was replaced not long before I purchased around 3 years ago, so I decided not to buy a remanufactured unit and go ahead and do the rebuild kits.

I'm going to need to remove the air dryer because the pressure relief valve  is facing the wrong way for me to do this with the dryer left mounted on the frame, as far as I can tell.

For those of you that may have done this, it looks like if I take the small bolt on the underside of the mounting bracket off and then loosen the clamp I can then rotate it a bit to get that little elbow loose. (See pictures) And then once I take the inlet and outlet airlines off she should come out correct? I did look around on this forum but so far couldn't find a good tutorial on how to remove this dryer on my specific coach.
As usual, any help is appreciated.

Re: Air dryer rebuild

Reply #1 –
Loosen evrything before you unbolt it from the mounting plate .

Re: Air dryer rebuild

Reply #2 –
I would suggest you disconnect the main airlines while still bolted down and slacken off small connection.
Way easier.
I rebuilt mine 3 times in the 12 yrs we owned  last coach. Simple and cheapest way.
Johnh

Re: Air dryer rebuild

Reply #3 –
When I've done this before, while the mounting bolts are still tight, I loosened the main in/out lines so I don't have to wrestle with the thing.  (ETA Johnh beat me to it!)

Next there should be two wires going to the heater ring that is inside that black plastic cap on the bottom.  If the unit has been replaced before there should be a splice connector on those lines, just follow them back for a bit.  If you don't find any splice, then you can either mark and cut those lines or remove the (3) screws from the plastic cover and the cover plus heater ring will drop out.  It looks like something you would find in an old coffee pot. Reman unit will have a new one, I'd guess rebuild kits will as well.

Then you can loosen that band clamp and remove the lower bolt, turn as necessary to gain access and loosen the control line that you indicated.  I think my control line was long enough to just lower the unit but don't remember for sure.

While its out its a good time to make yourself a "EDB" Emergency Dryer Bypass which can save you should the dryer ever go belly up while on the road.

Re: Air dryer rebuild

Reply #4 –
Many find it is not necessary to replace the pressure relief valve with every air dryer rebuild kit.

Re: Air dryer rebuild

Reply #5 –
Breaking everything loose before removing was definitely the ticket, that would have been a bear with it flopping around.

It wasn't too bad, but enough to make me swear a few times. One of the elbows (I believe the air inlet hose) was turning while I tried to loosen the main nut on the hose. Had to get creative to keep it from moving but finally got it to break loose.

This thing looks pretty scuzzy so I might just order a reman but they probably all look like this since they are exposed to the elements so I'm sure the re-build kit will do just fine, then maybe next time do the reman.

Re: Air dryer rebuild

Reply #6 –
Just started her up and after installing a reman air dryer and a new governor it's building no pressure.

Let it run at 1100 rpm for at least 5 min and the gauges are only reading 20 psi.

Not hearing any loud air leaks and when I shut it off theres a small amount of air coming out of the black plastic cap on the bottom of the dryer but goes away shortly.

Any suggestions?

There is some air in the rear wet tank and it was empty so there is some air pumping around.

Re: Air dryer rebuild

Reply #7 –
Quote from: dlkj07 –
Just started her up and after installing a reman air dryer and a new governor it's building no pressure.

Let it run at 1100 rpm for at least 5 min and the gauges are only reading 20 psi.

Not hearing any loud air leaks and when I shut it off theres a small amount of air coming out of the black plastic cap on the bottom of the dryer but goes away shortly.

Any suggestions?

There is some air in the rear wet tank and it was empty so there is some air pumping around.

Any suggestions.

Try the old governor and see if it builds pressure.  Are you 100 percent sure you got the same ports on the governor on the new one?  Out of the box not normally correct.

Re: Air dryer rebuild

Reply #8 –
Check your D2 governor installation.  Make sure you reconnected the reservoir hose to the proper port and installed the plugs in the unused ports.  Be sure the exhaust port is open.

Re: Air dryer rebuild

Reply #9 –
Pics of the correct ports on air governor on my 2003 U320.

Changing D2 - access method

Re: Air dryer rebuild

Reply #10 –
Quote from: AC7880 –
Try the old governor and see if it builds pressure.  Are you 100 percent sure you got the same ports on the governor on the new one?  Out of the box not normally correct.
I was pretty careful to mimic what came out, but I'll check again. It sounds like this is more likely a problem with the governor rather than the air dryer... hopefully.

Re: Air dryer rebuild

Reply #11 –
Tank drains closed?  They're easy to forget to go back and close after you open them to dump all the coach air.

Re: Air dryer rebuild

Reply #12 –
Quote from: Michelle –
Tank drains closed?  They're easy to forget to go back and close after you open them to dump all the coach air.
Yes, I only drained the rear tank...like I mentioned theres even air in the wet tank after running for awhile.

Re: Air dryer rebuild

Reply #13 –
Quote from: dlkj07 –
Not hearing any loud air leaks and when I shut it off theres a small amount of air coming out of the black plastic cap on the bottom of the dryer but goes away shortly.
If while you are running the engine, is there is air coming out of the black plastic cap on the air dryer?

That, I believe, would indicate either a bad air dryer, bad D2, or a D2 that is not plumbed in correctly.  The D2 should "signal" the air dryer to purge when the system is up to pressure, the purge is what comes out of the base of the air dryer, it should, AFAIK, only have air coming out at the end of the cycle.

At 20PSI and the engine running you should see that gauge move almost instantly.

Re: Air dryer rebuild

Reply #14 –
Well after a quick look at my old governor, I did install the air lines in the wrong holes...I shifted them over one hole...hopefully you can't damage the governor with air in the wrong hole. 🤦

Might be a week before I can get to it, but pretty sure that's the issue.

Re: Air dryer rebuild

Reply #15 –
Quote from: dlkj07 –
Well after a quick look at my old governor, I did install the air lines in the wrong holes...I shifted them over one hole...hopefully you can't damage the governor with air in the wrong hole. 🤦

Might be a week before I can get to it, but pretty sure that's the issue.

Glad you found it. No damage likely.

Re: Air dryer rebuild

Reply #16 –
Pics 2003 U320 air governor for any future searches:

Re: Air dryer rebuild

Reply #17 –
I added a couple of labels to Dans photo. 

When I replaced my D2 I did a poor job marking the air lines, as in I did not.  When the D2 was back in there was no clear set in my lines to indicate which went where so had to follow one back to be sure.

Re: Air dryer rebuild

Reply #18 –
Quote from: steve –
I added a couple of labels to Dans photo. 

When I replaced my D2 I did a poor job marking the air lines, as in I did not.  When the D2 was back in there was no clear set in my lines to indicate which went where so had to follow one back to be sure.

The one that goes to the dryer unloader also goes to the compressor.  Correct?

Re: Air dryer rebuild

Reply #19 –
Quote from: turbojack –
The one that goes to the dryer unloader also goes to the compressor.  Correct?
True, when the D2 is remotely mounted.

In the case discussed above (photo), the D2 is bolted directly to the compressor, so no separate line to compressor is required.