Home » Public Forums » GMCnet » Dana Compressor adjustments (How to)
| Dana Compressor adjustments [message #64542] |
Mon, 16 November 2009 17:37  |
Oldngray
Messages: 544
Registered: August 2009
Location: Punta Gorda Florida
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Seems I'm full of it today <BG> Another earlier post of mine had to do with not getting enuf pressure from my pump. Well I repaired a big leak and I am now able to get near 100 lbs psi out of the Dana before it shuts off. Just how do I adjust the pressure so that it shuts down at 100-105 lbs ?
I still have a really small leak and I am looking for it.
On the same subject, should the tank hold the pressure for a reasonable time? Mine looses it within minutes.
Richard MacDonald
Punta Gorda, Florida
Sold our TZE April 2015
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| Re: Dana Compressor adjustments [message #64547 is a reply to message #64542] |
Mon, 16 November 2009 18:07  |
C Boyd
Messages: 2629
Registered: April 2006
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| Oldngray wrote on Mon, 16 November 2009 18:37 |
Seems I'm full of it today <BG> Another earlier post of mine had to do with not getting enuf pressure from my pump. Well I repaired a big leak and I am now able to get near 100 lbs psi out of the Dana before it shuts off. Just how do I adjust the pressure so that it shuts down at 100-105 lbs ?
I still have a really small leak and I am looking for it.
On the same subject, should the tank hold the pressure for a reasonable time? Mine looses it within minutes.
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Sir: with my experience with big trucks, I would advise to keep on digging and finding air leaks until you can get the coach to hold air overnight before messing with the air governor adjustment. I use a concentrated soap mixture, or I borrow a handheld listening device that Wally uses to find air leaks in air handlers working on 3-5 lb pressure. Radio shack has some that would probably work. I was impressed by the way I could hear air leaks.
C. Boyd
76 Crestmont
East Tennessee
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| Re: Dana Compressor adjustments [message #64562 is a reply to message #64547] |
Mon, 16 November 2009 19:20 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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Air tank should hold air overnight, all other things being equal. If it is the original tank, check for rust pin holes, especially on the underneath. There was no water/air separator in the original design. My air tank was a leaking sponge. I bought a SS one from the guy in Canada, and have never looked back. I did put one of the air/water filters on my tank. amasing the amount of water it removes.
You could also remove the fittings to the tank and clean the threads and cover them with teflon tape. Do not allow the teflon tape to enter the tank. No sense in creating additional problems.
Tom Phipps,
75 GMC Ex-Avion
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: Dana Compressor adjustments [message #64565 is a reply to message #64542] |
Mon, 16 November 2009 19:26 |
Oldngray
Messages: 544
Registered: August 2009
Location: Punta Gorda Florida
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I do believe I found it. I used dawn (thanks for the suggestion) and discovered that the water filter was leaking ever so slightly.
Compressor pulled 105 lbs and shutdown. Will check the tank in the am to see if it holds.
Richard MacDonald
Punta Gorda, Florida
Sold our TZE April 2015
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| Re: Dana Compressor adjustments [message #64568 is a reply to message #64542] |
Mon, 16 November 2009 19:35 |
idrob
Messages: 645
Registered: January 2005
Location: Central Idaho
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| Oldngray wrote on Mon, 16 November 2009 15:37 |
Seems I'm full of it today <BG> Another earlier post of mine had to do with not getting enuf pressure from my pump. Well I repaired a big leak and I am now able to get near 100 lbs psi out of the Dana before it shuts off. Just how do I adjust the pressure so that it shuts down at 100-105 lbs ?
I still have a really small leak and I am looking for it.
On the same subject, should the tank hold the pressure for a reasonable time? Mine looses it within minutes.
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If it is a Penn pressure switch (my original on a '76 was) here is a photo of the interior and how to adjust it. After I found all the leaks in my overall system it would hold pressure for a week or more with the valves in "hold" and when driving in the travel mode, would only cycle about once or twice a day. It did take me forever to find all the leaks.
http://www.gmcmhphotos.com/photos/showphoto.php?photo=15410
Rob Allen
former owner of '76 x-PB
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| Re: [GMCnet] Dana Compressor adjustments [message #64575 is a reply to message #64542] |
Mon, 16 November 2009 20:38 |
Charles
Messages: 455
Registered: January 2004
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Put soapy water on the bottom side of your tank. Sounds like you have a
leak.
After 30 + years they start to rust out.
Charles
----- Original Message -----
From: "Richard MacDonald" <rm1936@gmail.com>
To: <gmclist@temp.gmcnet.org>
Sent: Monday, November 16, 2009 5:37 PM
Subject: [GMCnet] Dana Compressor adjustments
>
>
> Seems I'm full of it today <BG> Another earlier post of mine had to do
> with not getting enuf pressure from my pump. Well I repaired a big leak
> and I am now able to get near 100 lbs psi out of the Dana before it shuts
> off. Just how do I adjust the pressure so that it shuts down at 100-105
> lbs ?
> I still have a really small leak and I am looking for it.
>
> On the same subject, should the tank hold the pressure for a reasonable
> time? Mine looses it within minutes.
>
> --
> Richard MacDonald
> Punta Gorda, Florida
> 76 Edgemonte
> 94 K2500 6.5 Turbo Diesel Silverado
>
>
> _______________________________________________
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Charles Wersal
Duncanville, Texas
26 foot 1975 Glenbrook
Pandora's Box
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| Re: [GMCnet] Dana Compressor adjustments [message #64624 is a reply to message #64542] |
Tue, 17 November 2009 14:11 |
Rick Denney
Messages: 430
Registered: January 2004
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Richard MacDonald writes...
> On the same subject, should the tank hold the pressure for a
> reasonable time? Mine looses it within minutes.
Yes, it should hold pressure indefinitely (in a perfect world) or for
days (in my world).
Remember, though, that the pressure in the tank will always be higher
than the pressure needed in the bags. The bags will need 80 or 90 psi
depending ono the weight of the coach--maybe less if your coach is
light like mine. The purpose of the tank is to provide a reservoir of
pressure to be used by the leveling valves or control valves to raise
the coach. When the bags have excess pressure, it is dumped to the
atmosphere. So, when driving, it is normal for the tank pressure to be
used up and if the pump has to run every couple of hours that's not
unusual.
The pressure in the tank is controlled by a standard air-system
pressure switch. The usual replacements that you get for any air
compressor will work fine, and most adjustible models come set from
the factory to turn on a 90-100 psi and turn off at 120-125 psi. Those
values work fine. If your pressure switch is set for something lower,
the tank might not be able to provide the needed pressure for raising
operations.
My coach is at maximum raise at 100 psi or even a bit less, but mine
is light.
There are many possible leak sources, including the TEE connections
(which are probably the plastic ones on your coach), tubing that is
notched from rubbing on a frame rail, the check valve in the pump
leaking, leaks in the tanks, leaks in the control valves (or solenoid
valves on Electro Level systems), leaks in the tank, or leaks in the
various things screwed into the tank. There is a pressure pop-off
valve in the tank that can leak, plus a moisture drain valve that can
leak. Every one of these has leaked on my coach at one time or
another. Fortunately, the system uses standard 1/4" DOT nylon tubing
that is also used on big trucks, so the fittings are reasonably
available. Parker is a good brand.
Rick "who has a new check valve and water filter still to install"
Denney
'73 230 Ex-Glacier "Jaws"
Northern Virginia
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| Re: Dana Compressor adjustments [message #64629 is a reply to message #64542] |
Tue, 17 November 2009 14:50 |
Oldngray
Messages: 544
Registered: August 2009
Location: Punta Gorda Florida
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Well the pump seems to work nicely, turns on when asked and turns off at 105 lbs in about 45 seconds +-. The coach seems to be at its maximum height at least it is as high as I have seen it since we bought it.
The tank leak down is fairly quick, about 5 lbs every ten minutes or so. I have used soap all over the system (inside) and yet to do so around the air bags. The Coach does not settle, actually Jeff Sirum commented that from January to August the Coach stayed at the same height.
I would like to install schraders just in case, just unsure how to go about it. I have read several writeups on it but my mind cannot seem to get around it. Just another project.
Richard MacDonald
Punta Gorda, Florida
Sold our TZE April 2015
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| Re: [GMCnet] Dana Compressor adjustments [message #64633 is a reply to message #64629] |
Tue, 17 November 2009 14:56 |
Dennis S
Messages: 3046
Registered: November 2005
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Richard,
Don't know if it has been mentioned -- but the check valve could be leaking, so your air loss would be back through the compressor.
Dennis
Dennis Sexton
73 GMC
Germantown, TN
USA
-----Original Message-----
From: Richard MacDonald <rm1936@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Tue, Nov 17, 2009 2:50 pm
Subject: Re: [GMCnet] Dana Compressor adjustments
Well the pump seems to work nicely, turns on when asked and turns off at 105 lbs
n about 45 seconds +-. The coach seems to be at its maximum height at least it
s as high as I have seen it since we bought it.
he tank leak down is fairly quick, about 5 lbs every ten minutes or so. I have
sed soap all over the system (inside) and yet to do so around the air bags.
he Coach does not settle, actually Jeff Sirum commented that from January to
ugust the Coach stayed at the same height.
would like to install schraders just in case, just unsure how to go about it.
have read several writeups on it but my mind cannot seem to get around it.
ust another project.
--
ichard MacDonald
unta Gorda, Florida
6 Edgemonte
4 K2500 6.5 Turbo Diesel Silverado
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MCnet mailing list
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Dana Compressor adjustments [message #64637 is a reply to message #64629] |
Tue, 17 November 2009 15:58 |
Rick Denney
Messages: 430
Registered: January 2004
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Richard MacDonald writes...
> Well the pump seems to work nicely, turns on when asked and turns
> off at 105 lbs in about 45 seconds +-. The coach seems to be at its
> maximum height at least it is as high as I have seen it since we bought it.
> The tank leak down is fairly quick, about 5 lbs every ten minutes
> or so. I have used soap all over the system (inside) and yet to do
> so around the air bags. The Coach does not settle, actually Jeff
> Sirum commented that from January to August the Coach stayed at the same height.
> I would like to install schraders just in case, just unsure how to
> go about it. I have read several writeups on it but my mind cannot
> seem to get around it. Just another project.
Richard, I would suggest a little research into how the air system
works. I think you have an Electro-Level I system, which I'm not that
familiar with, but in hold the pump, tank, control valves, and
everything attached to the tank should hold pressure and the rest is
out of the circuit. Getting rid of leaks around the bags is a
different process and diagnostic procedure than getting rid of leaks
at the tank.
If your coach isn't settling when you have it in Hold, then your leaks
are between the pump, tank, pressure switch, and control valves. If
the tank pressure holds up but the bags leak down, then the leaks are
around the bags, leveling valves, and tubing going back to the control
valves. If your control valves are leaking, the bags would probably
not stay up. A leak in the check valve on the pump would also not
appear with the soap-bubble test--the intake of the Dana pump is a
little big to blow bubbles. The Dana pumps use a rubber flap as a
check valve and it does not hold--most have added a good
brass/stainless steel check valve downstream from the pump.
How are you measuring tank pressure?
The bags will always have less pressure than the tank, unless the
control switches are in Raise for an extended period. In Travel mode,
the bags are regulated by the leveling valves, and those feed air from
the tank (by whatever means) only when needed. The tank should always
have more pressure than the bags during normal operation.
I wrote an article on the earlier Power Level system, and that may
help you understand it, assuming that's not one of the articles you've
already read. The Electro-Level I system works basically the same way,
as I understand it. The Electro-Level II system is much different, and
uses electrical leveling controls rather than valves. That article is
linked on this page:
http://www.gmceast.com/technical/
Rick "diagnosis is based on theory of operation" Denney
'73 230 Ex-Glacier "Jaws"
Northern Virginia
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| Re: [GMCnet] Dana Compressor adjustments [message #64640 is a reply to message #64637] |
Tue, 17 November 2009 16:30 |
Oldngray
Messages: 544
Registered: August 2009
Location: Punta Gorda Florida
Karma: 0
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Senior Member |
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| Rick Denney wrote on Tue, 17 November 2009 16:58 |
Richard MacDonald writes...
> Well the pump seems to work nicely, turns on when asked and turns
> off at 105 lbs in about 45 seconds +-. The coach seems to be at its
> maximum height at least it is as high as I have seen it since we bought it.
> The tank leak down is fairly quick, about 5 lbs every ten minutes
> or so. I have used soap all over the system (inside) and yet to do
> so around the air bags. The Coach does not settle, actually Jeff
> Sirum commented that from January to August the Coach stayed at the same height.
> I would like to install schraders just in case, just unsure how to
> go about it. I have read several writeups on it but my mind cannot
> seem to get around it. Just another project.
Richard, I would suggest a little research into how the air system
works. I think you have an Electro-Level I system, which I'm not that
familiar with, but in hold the pump, tank, control valves, and
everything attached to the tank should hold pressure and the rest is
out of the circuit. Getting rid of leaks around the bags is a
different process and diagnostic procedure than getting rid of leaks
at the tank.
If your coach isn't settling when you have it in Hold, then your leaks
are between the pump, tank, pressure switch, and control valves. If
the tank pressure holds up but the bags leak down, then the leaks are
around the bags, leveling valves, and tubing going back to the control
valves. If your control valves are leaking, the bags would probably
not stay up. A leak in the check valve on the pump would also not
appear with the soap-bubble test--the intake of the Dana pump is a
little big to blow bubbles. The Dana pumps use a rubber flap as a
check valve and it does not hold--most have added a good
brass/stainless steel check valve downstream from the pump.
How are you measuring tank pressure?
The bags will always have less pressure than the tank, unless the
control switches are in Raise for an extended period. In Travel mode,
the bags are regulated by the leveling valves, and those feed air from
the tank (by whatever means) only when needed. The tank should always
have more pressure than the bags during normal operation.
I wrote an article on the earlier Power Level system, and that may
help you understand it, assuming that's not one of the articles you've
already read. The Electro-Level I system works basically the same way,
as I understand it. The Electro-Level II system is much different, and
uses electrical leveling controls rather than valves. That article is
linked on this page:
http://www.gmceast.com/technical/
Rick "diagnosis is based on theory of operation" Denney
'73 230 Ex-Glacier "Jaws"
Northern Virginia
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The Placard just says Electro Level no 1 or 2.
I just readjusted the cutoff to 125psi, it took 50 seconds for the pump to go from 0 to 125, the pressure gauge attached to the pump is what I am reading.
As I understand, the intakes are in the front of the pump and I would have to remove the entire system to get at those two hoses.
Something for later on.
While traveling, I have set the switch to hold, perhaps I should set it to auto since my tank does not hold the pressure, thereby having the pump come on whenever the pressure drops below the cutin.
Rick, I have read about the Level System and refer to the manual most every day, however, my retention abilities are somewhat suspect 
Trust you will bear with me.
Thanks
Richard MacDonald
Punta Gorda, Florida
Sold our TZE April 2015
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| Re: [GMCnet] Dana Compressor adjustments [message #64649 is a reply to message #64642] |
Tue, 17 November 2009 17:03 |
Rick Denney
Messages: 430
Registered: January 2004
Karma: 0
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Senior Member |
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Hal Kading writes...
> I agree with Dennis, probably the check valve. The original check
> valves were steel and very prone to rusting. Replace with stainless or brass, if not already done.
Your coach ever had a check valve? My '73 (with Power Level) did not,
except for the rubber flap check valve in the Dana pump. Maybe they
added it to the later systems.
My Viair replacement pump came with a check valve, but I'm not sure I
fully trust it, and am replacing with a higher-quality check valve
that I bought from Jim K.
The reason is that the tank side of my system still leaks down faster
than it should, and I have a new tank, new pop-off pressure switch,
new drain valve, new tubing, new connections, new pressure switch, new
gauge, new Slaten control valves, and new pump. The cheapie check
valve that came with the pump is the only suspect item left.
And, Richard, the Electro-Level I didn't have the I--when they made it
they weren't anticipating that there would be a II, heh, heh.
Rick "also with a pesky leak in the right bag" Denney
'73 230 Ex-Glacier "Jaws"
Northern Virginia
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| Re: [GMCnet] Dana Compressor adjustments [message #64660 is a reply to message #64649] |
Tue, 17 November 2009 17:47 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Rick,
The Avions have the Power Level System also which I like as it so bloody
simple. Double Trouble came with a Thomas pump that works fine and JR's
valves. Unfortunately the system leaked pretty badly.
While at the COOP last year we pulled everything out and after replacing the
body pads (didn't find any crushed lines) replaced all the lines, fittings,
air bag manifolds, seals, you name it. When we got done it still leaked down
slowly. DAMN! This year at Tom Hampton's shop we found the leaks; it was the
o-rings that seal the fittings in the ends of the OEM air bags. We took both
bags out and put new o-rings that had larger cross sections. The pump cuts
out at 140 psi and only looses 1-2 psi per day even with the air bag
isolation valve on. I could chase that but why bother!
The thing I noticed is that the machined surface inside the OEM airbags on
which the o-ring seats is lousy. It is tapered with the taper going towards
the inside of the bag. If you tighten the fitting to much you force the
o-ring away from the sides and into the hole! I cut the fitting end off a
bad airbag at Tom's shop and brought it back to Sydney with me. I'm going to
make some flat gaskets about 1/8" thick of a fairly high durometer rubber.
The OD will be the size of the threaded hole in the air bag and the id will
be 1/4". You would be able to tighten it down more and the cross section
between the OD and ID would help keep it from squeezing out.
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Rick Denney
Sent: Wednesday, 18 November 2009 10:03 AM
To: Hal Kading
Subject: Re: [GMCnet] Dana Compressor adjustments
Hal Kading writes...
> I agree with Dennis, probably the check valve. The original check
> valves were steel and very prone to rusting. Replace with stainless or
brass, if not already done.
Your coach ever had a check valve? My '73 (with Power Level) did not,
except for the rubber flap check valve in the Dana pump. Maybe they
added it to the later systems.
My Viair replacement pump came with a check valve, but I'm not sure I
fully trust it, and am replacing with a higher-quality check valve
that I bought from Jim K.
The reason is that the tank side of my system still leaks down faster
than it should, and I have a new tank, new pop-off pressure switch,
new drain valve, new tubing, new connections, new pressure switch, new
gauge, new Slaten control valves, and new pump. The cheapie check
valve that came with the pump is the only suspect item left.
And, Richard, the Electro-Level I didn't have the I--when they made it
they weren't anticipating that there would be a II, heh, heh.
Rick "also with a pesky leak in the right bag" Denney
'73 230 Ex-Glacier "Jaws"
Northern Virginia
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Dana Compressor adjustments [message #64669 is a reply to message #64542] |
Tue, 17 November 2009 18:37 |
Oldngray
Messages: 544
Registered: August 2009
Location: Punta Gorda Florida
Karma: 0
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Senior Member |
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Well Folks, I just discovered that the pump is a Hadley not a Dana. It is a two cyl with a blue belt cover but I found a sticker that says Hadley and has a animated fat guy blowing air. It looks just like the two cyl GMC pumps that I have seen on other coaches.
Don't know if it matters but it is different.
Richard MacDonald
Punta Gorda, Florida
Sold our TZE April 2015
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