Thomas Compressor/Vacuum pump

D

dave lowry

New member
Jul 7, 1998
615
0
0
Now this is EXCITING!

I'm still using the original Dana which is under the streetside bed in my
'76 rear bath Royale. Either it's no good or the check valve is leaking, or
both, so that the compressor cycles for 30 to 45 seconds every couple of
minutes (even on "hold"), and it takes forever to raise the coach. Also, I
want to add an auxilliary vacuum pump for the brakes.

If I'm correctly understanding the recent thread, there's a good
possibility I can replace the old Dana with a Thomas 315 or 317 to fix both
problems. Here's what I envision:

1) Mount the new compressor in the engine compartment (where it wouldn't
need a long power lead), together with the solenid valves & etc. (See note
below) including a quick-connect fitting to inflate anything else that
needs it.

2) Run a 1/4" copper pressure line back to where the Dana used to be, tying
it to the check valve (I'll replace that too).

3) Run a 1/4" copper vacuum line to the brake booster, with the appropriate
vacuum switch
to turn on the pump when vacuum is needed.

An added benefit for me would be that I could easily direct my mechanic to
do the work.

Note: If someone could PLEASE make the diagram and part numbers available
for a pressure / vacuum system, I believe many could benefit by this
moderately priced upgrade.

Watching.

Dave (& Dege), Santa Barbara, '76 Royale 26'
 
Your logic is perfect as usual Arch. One would have to have several valves
to switch back and forth between vacuum and air as needed. In other words
when the suspension needed air the vacuum side would be vented and pump up
the air tank and when the vacuum side activated the air side would be vented.

Sounds to complicated for a simple job.

>GMCers
>
>I am going to try to say this one more time. Then I will let it be. I dont
>think this will work! (yes that is theory) I have no experience with this!
>
>First lets take the compressor operation. How can a compressor
>compress air when it drawing against a vacuum? There is not much to
>compress. A compressor must have air to compress. Vacuums dont
>compress. Where is the compressor going to get the air to compress--
>surely not from a vacuum? Now it might find a little air but surely its
>ability to compress will be severely degraded.
>
>Now lets look at the vacuum aspect of this pump. OK we need vacuum
>when the engine dies. We need it in a hurry!! This pump is going to
>have to fire up with 120 PSI built up in the air tank this is only 30 PSI
>from its limit. Where is it going to put the air that it is taking out of the
>booster---------in the air tank--------mine has a 150 PSI pop-off------the
>limit of the compressor-----------I dont think I am going to get much
>vacuum under those conditions. Not to mention how little faith I have in
>pop-off valves.
>
>A compressor works because it can draw air at atmospheric pressure
>not at a vacuum. A vacuum pump works because it can dump the air
>at atmospheric pressure not at 120 PSI !
>
>OK all of you engineers tell me the flaw in this logic. I will stand and fight
>on this one.
>
>Take Care
>Arch
>
>In a message dated 1/30/99 5:05:33 PM Central Standard Time, dlowry
>writes:
>
>>
>> I'm still using the original Dana which is under the streetside bed in my
>> '76 rear bath Royale. Either it's no good or the check valve is leaking, or
>> both, so that the compressor cycles for 30 to 45 seconds every couple of
>> minutes (even on "hold"), and it takes forever to raise the coach. Also, I
>> want to add an auxilliary vacuum pump for the brakes.
>>
>> If I'm correctly understanding the recent thread, there's a good
>> possibility I can replace the old Dana with a Thomas 315 or 317 to fix both
>> problems. Here's what I envision:
>>
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach
 
Emory Stora wrote "past life I was an engineer" in his response to Arch's '
Ok all of you engineers'.
It has been my experience working with mechanics and engineers of all types
that one must never underestimate the creative and innovative minds of the
mechanic that employs logic. He just wasn't as fortunate as some to spend 4
or more years in a college classroom environment reading all the writings of
the learned folks, but he has the knowledge and knowledge is power. Stick to
your guns Arch.
Rivers fell here, but will rise again when it warms up in the mountains.
srchrls
 
It seems like every so often we need to repeat the warning on the use of
copper tubing for RV use. Copper tubing has it place in short runs in
areas not subject to vibration, flexing and stress. This is extremely
important in the use of 1/4" copper. 3/8" copper tubing is more
forgiving. The best all around material to use in a motor home is the
polytube type and it is low cost even in the 3/8 size as compared to
copper. The only thing that you will see the truckers use is steel
lines and the polytube. Copper in air service will corrode and
contaminate your air system. Also the other standard warning for
fittings is that you NEVER use teflon tape!!! Only use the paste type!

J.R. Wright
GMC Greatlaker
77 Eleganza II
Michigan

>
> -- [ From: Eugene Fisher * EMC.Ver #2.5.3 ] --
>
> sounds like you have some serious leaks. I just came back from another
> tuneup trip and after the inital pump-up I leave the switch on auto and
> the pump never comes on again. Your pump might be ok gene
> -------- REPLY, Original message follows --------
>
> Date: Saturday, 30-Jan-99 06:07 PM
>
> From: Dave Lowry \ Internet: (dlowry)
> To: gmclist \ Internet: (gmcmotorhome
> .org)
>
> Attachment: mimemsg.doc Code: 024D44L \ Created: Unknown [3 Kb]
>
> Subject: GMC: Thomas Compressor/Vacuum pump
>
> Now this is EXCITING!
>
> I'm still using the original Dana which is under the streetside bed in
> my '76 rear bath Royale. Either it's no good or the check valve is
> leaking, or both, so that the compressor cycles for 30 to 45 seconds
> every couple of minutes (even on "hold"), and it takes forever to raise
> the coach. Also, I want to add an auxilliary vacuum pump for the brakes.
>
> If I'm correctly understanding the recent thread, there's a good
> possibility I can replace the old Dana with a Thomas 315 or 317 to fix
> both problems. Here's what I envision:
>
> 1) Mount the new compressor in the engine compartment (where it wouldn't
> need a long power lead), together with the solenid valves & etc. (See
> note below) including a quick-connect fitting to inflate anything else
> that needs it.
>
> 2) Run a 1/4" copper pressure line back to where the Dana used to be,
> tying it to the check valve (I'll replace that too).
>
> 3) Run a 1/4" copper vacuum line to the brake booster, with the
> appropriate
> vacuum switch
> to turn on the pump when vacuum is needed.
>
> An added benefit for me would be that I could easily direct my mechanic
> to do the work.
>
> Note: If someone could PLEASE make the diagram and part numbers
> available for a pressure / vacuum system, I believe many could benefit
> by this moderately priced upgrade.
>
> Watching.
>
> Dave (& Dege), Santa Barbara, '76 Royale 26'
>
> -------- REPLY, End of original message --------
>
> --
> Gene 76Palm Beach /Or/CA
>
> GMC Technical Information
> http://www.california.com/~eagle/
 
John, in general I agree with you. However I did add a copper loop
to my air compressor outlet as shown on Gene Fishers home page to
condense moisture from the air. Since the air system is not a crucial
system I will chance the possible inconvenence of a leak developing.

Ted Schurman
73 Glacier 73

>
> It seems like every so often we need to repeat the warning on the use of
> copper tubing for RV use. Copper tubing has it place in short runs in
> areas not subject to vibration, flexing and stress. This is extremely
> important in the use of 1/4" copper. 3/8" copper tubing is more
> forgiving. The best all around material to use in a motor home is the
> polytube type and it is low cost even in the 3/8 size as compared to
> copper. The only thing that you will see the truckers use is steel
> lines and the polytube. Copper in air service will corrode and
> contaminate your air system. Also the other standard warning for
> fittings is that you NEVER use teflon tape!!! Only use the paste type!
>
> J.R. Wright
> GMC Greatlaker
> 77 Eleganza II
> Michigan
>

> >
> > -- [ From: Eugene Fisher * EMC.Ver #2.5.3 ] --
> >
> > sounds like you have some serious leaks. I just came back from another
> > tuneup trip and after the inital pump-up I leave the switch on auto and
> > the pump never comes on again. Your pump might be ok gene
> > -------- REPLY, Original message follows --------
> >
> > Date: Saturday, 30-Jan-99 06:07 PM
> >
> > From: Dave Lowry \ Internet: (dlowry)
> > To: gmclist \ Internet: (gmcmotorhome
> > .org)
> >
> > Attachment: mimemsg.doc Code: 024D44L \ Created: Unknown [3 Kb]
> >
> > Subject: GMC: Thomas Compressor/Vacuum pump
> >
> > Now this is EXCITING!
> >
> > I'm still using the original Dana which is under the streetside bed in
> > my '76 rear bath Royale. Either it's no good or the check valve is
> > leaking, or both, so that the compressor cycles for 30 to 45 seconds
> > every couple of minutes (even on "hold"), and it takes forever to raise
> > the coach. Also, I want to add an auxilliary vacuum pump for the brakes.
> >
> > If I'm correctly understanding the recent thread, there's a good
> > possibility I can replace the old Dana with a Thomas 315 or 317 to fix
> > both problems. Here's what I envision:
> >
> > 1) Mount the new compressor in the engine compartment (where it wouldn't
> > need a long power lead), together with the solenid valves & etc. (See
> > note below) including a quick-connect fitting to inflate anything else
> > that needs it.
> >
> > 2) Run a 1/4" copper pressure line back to where the Dana used to be,
> > tying it to the check valve (I'll replace that too).
> >
> > 3) Run a 1/4" copper vacuum line to the brake booster, with the
> > appropriate
> > vacuum switch
> > to turn on the pump when vacuum is needed.
> >
> > An added benefit for me would be that I could easily direct my mechanic
> > to do the work.
> >
> > Note: If someone could PLEASE make the diagram and part numbers
> > available for a pressure / vacuum system, I believe many could benefit
> > by this moderately priced upgrade.
> >
> > Watching.
> >
> > Dave (& Dege), Santa Barbara, '76 Royale 26'
> >
> > -------- REPLY, End of original message --------
> >
> > --
> > Gene 76Palm Beach /Or/CA
> >
> > GMC Technical Information
> > http://www.california.com/~eagle/
 
Are the 'Compression' Fittings used on polytube OK?? Is there any concern
over using these instead of the normal 'Flare' type used with copper??
(Age, vibration....)??

>It seems like every so often we need to repeat the warning on the use of
>copper tubing for RV use. Copper tubing has it place in short runs in
>areas not subject to vibration, flexing and stress. This is extremely
>important in the use of 1/4" copper. 3/8" copper tubing is more
>forgiving. The best all around material to use in a motor home is the
>polytube type and it is low cost even in the 3/8 size as compared to
>copper. The only thing that you will see the truckers use is steel
>lines and the polytube. Copper in air service will corrode and
>contaminate your air system. Also the other standard warning for
>fittings is that you NEVER use teflon tape!!! Only use the paste type!
>
>J.R. Wright
>GMC Greatlaker
>77 Eleganza II
>Michigan
>

>>
>> -- [ From: Eugene Fisher * EMC.Ver #2.5.3 ] --
>>
>> sounds like you have some serious leaks. I just came back from another
>> tuneup trip and after the inital pump-up I leave the switch on auto and
>> the pump never comes on again. Your pump might be ok gene
>> -------- REPLY, Original message follows --------
>>
>> Date: Saturday, 30-Jan-99 06:07 PM
>>
>> From: Dave Lowry \ Internet: (dlowry)
>> To: gmclist \ Internet: (gmcmotorhome
>> .org)
>>
>> Attachment: mimemsg.doc Code: 024D44L \ Created: Unknown [3 Kb]
>>
>> Subject: GMC: Thomas Compressor/Vacuum pump
>>
>> Now this is EXCITING!
>>
>> I'm still using the original Dana which is under the streetside bed in
>> my '76 rear bath Royale. Either it's no good or the check valve is
>> leaking, or both, so that the compressor cycles for 30 to 45 seconds
>> every couple of minutes (even on "hold"), and it takes forever to raise
>> the coach. Also, I want to add an auxilliary vacuum pump for the brakes.
>>
>> If I'm correctly understanding the recent thread, there's a good
>> possibility I can replace the old Dana with a Thomas 315 or 317 to fix
>> both problems. Here's what I envision:
>>
>> 1) Mount the new compressor in the engine compartment (where it wouldn't
>> need a long power lead), together with the solenid valves & etc. (See
>> note below) including a quick-connect fitting to inflate anything else
>> that needs it.
>>
>> 2) Run a 1/4" copper pressure line back to where the Dana used to be,
>> tying it to the check valve (I'll replace that too).
>>
>> 3) Run a 1/4" copper vacuum line to the brake booster, with the
>> appropriate
>> vacuum switch
>> to turn on the pump when vacuum is needed.
>>
>> An added benefit for me would be that I could easily direct my mechanic
>> to do the work.
>>
>> Note: If someone could PLEASE make the diagram and part numbers
>> available for a pressure / vacuum system, I believe many could benefit
>> by this moderately priced upgrade.
>>
>> Watching.
>>
>> Dave (& Dege), Santa Barbara, '76 Royale 26'
>>
>> -------- REPLY, End of original message --------
>>
>> --
>> Gene 76Palm Beach /Or/CA
>>
>> GMC Technical Information
>> http://www.california.com/~eagle/
>
 
Ted;
I think you are misguided if you think that the copper loop will "condense
water" from the compressed air. Just where would this water go???? I believe
that the reason for the copper loop is to cool the air. Water filters can be
added to the system; I have one (actually two since I have two compressors)
filtering the air before it goes into the tank. I got these filters from Jim
Bounds. IIRC the price was around $15 each.
Gary
'77 Kingsley
North Bend, Oregon Coast

> John, in general I agree with you. However I did add a copper loop
> to my air compressor outlet as shown on Gene Fishers home page to
> condense moisture from the air. Since the air system is not a crucial
> system I will chance the possible inconvenence of a leak developing.
>
> Ted Schurman
> 73 Glacier 73
>
 
Ted,

I did the same thing - added a loop of copper between the compressor and
an in-line filter. The object is to cool the air and hence encourage
condensation here, where it can accumulate in the filter's bowl instead
of in the air tank. All this is upstream from a check valve, so I
figured a minor leak here would have an insignificant effect.

Richard

>John, in general I agree with you. However I did add a copper loop
>to my air compressor outlet as shown on Gene Fishers home page to
>condense moisture from the air. Since the air system is not a crucial
>system I will chance the possible inconvenence of a leak developing.
 
Gary, I too have a water filter installed after the copper tubing.
The purpose of the tubing is indeed to cool the air which will then turn
the water vapor to liquid water which can be strained by the water
filter. If the air is not cooled then the water will pass through the
filter as water vapor, a gas. When it gets to the storage tank then it
cools and forms liquid water in the tank.

Ted Schurman
73 Glacier 73

>
> Ted;
> I think you are misguided if you think that the copper loop will "condense
> water" from the compressed air. Just where would this water go???? I believe
> that the reason for the copper loop is to cool the air. Water filters can be
> added to the system; I have one (actually two since I have two compressors)
> filtering the air before it goes into the tank. I got these filters from Jim
> Bounds. IIRC the price was around $15 each.
> Gary
> '77 Kingsley
> North Bend, Oregon Coast
>

>
> > John, in general I agree with you. However I did add a copper loop
> > to my air compressor outlet as shown on Gene Fishers home page to
> > condense moisture from the air. Since the air system is not a crucial
> > system I will chance the possible inconvenence of a leak developing.
> >
> > Ted Schurman
> > 73 Glacier 73
> >
 
OK. Now I'm less excited.

First, I'll not use copper. (I knew that. Must have had "Senior Moment".)

Sounds like I first need to find the leaks. Twice I've had my helper use
the soapy liqiud without finding any, but it still has a very slow leak on
the left side (3 or 4 days to fully settle) and the compressor cycles far
too often while we're under way. I think I'm going to have to bite the
bullet and let my high-priced mechanic try to find the problem (@ $60 per).
Maybe if I study past posts to GMCnet and articles in Cinnabar's news
letter and print some for the mechanic's use, he'll be able to find the
problem before I run out of money.

Questions: 1) Would a faulty check valve cause the compressor to cycle
with the system on "hold"? 2) Where would be the best place to tie in a
guage to monitor the pressure?

After the leaks are eliminated, I'll deal with the slow pump-up by either
having the Dana rebuilt or replaced with a Thomas 315).

As for the auxilliary vacuum pump, I may have to buy a new one, as it's
pretty difficult to pay someone else to scavange the right parts at the
local junk yard. Again, I'll review past posts to learn more before I
proceed.

Sorry to be so long winded, but since I can't do the work myself, I need to
minimize
other's "research" time, and GMCnetters are are by far the best bunch to
bounce ideas off of.

While I'm at it, let me say that this site is a fantastic example of how
the internet can be used to benefit the masses. I vote for NOT becoming a
GMCMI chapter or envoking too many rules. GMCnet, despite minor disruptions
, is an information resource and should be restricted to that.
One-on-one social comentary should be conducted privately, and not on the
GMCnet. Patrick, you had it right from the very begining; sharing
information of common (GMC) interest. Period.

I'm done.

Dave, '76 Royale, Santa Barbara (sunny & 70)
 
Thom,
I recommend the Parker Brass Compression Fittings. These type of
fittings have been used for many years without failure problems.
Sweglock Brand fittings are also of equal quality. The 1/4" tubing size
are rated at 400 PSI @ 73 deg F which is fine for Motorhome use. The
3/8" are rated at 200 PSI @ 73 deg F. You can find these at most
industrial supply houses or at catalog companies like Grainger &
McMaster. The 45 deg. Brass flare fitting are rated much higher when
using copper tubing, but you just don't need to have that much overkill
on rating. I have been in the Instrument and air system design for 27
years and my warning on copper in air service is valid. The least
amount of corrosion from the condensed moisture can and will contaminate
your solenoids over a period of time. The schrader valve that is used
for draining the water out of the air take can have a slow leak caused
by rust and corrosion. I would recommend a 304 or 316L stainless steel
tubing along with a good filter in the suction of the air compressor and
weekly draining of your air tank. I have a coalescing filter in my air
line from the compressor to the air tank to knock out any moisture and
other impurities to my air system and not let is get as far as my air
tank. Anyway I have rambled on here too long and I am sure there are
other out there with other opinions and ideas.

J.R. Wright
GMC Greatlaker
77 Eleganza II
Michigan

>
> Are the 'Compression' Fittings used on polytube OK?? Is there any concern
> over using these instead of the normal 'Flare' type used with copper??
> (Age, vibration....)??
>

> >It seems like every so often we need to repeat the warning on the use of
> >copper tubing for RV use. Copper tubing has it place in short runs in
> >areas not subject to vibration, flexing and stress. This is extremely
> >important in the use of 1/4" copper. 3/8" copper tubing is more
> >forgiving. The best all around material to use in a motor home is the
> >polytube type and it is low cost even in the 3/8 size as compared to
> >copper. The only thing that you will see the truckers use is steel
> >lines and the polytube. Copper in air service will corrode and
> >contaminate your air system. Also the other standard warning for
> >fittings is that you NEVER use teflon tape!!! Only use the paste type!
> >
> >J.R. Wright
> >GMC Greatlaker
> >77 Eleganza II
> >Michigan
> >

> >>
> >> -- [ From: Eugene Fisher * EMC.Ver #2.5.3 ] --
> >>
> >> sounds like you have some serious leaks. I just came back from another
> >> tuneup trip and after the inital pump-up I leave the switch on auto and
> >> the pump never comes on again. Your pump might be ok gene
> >> -------- REPLY, Original message follows --------
> >>
> >> Date: Saturday, 30-Jan-99 06:07 PM
> >>
> >> From: Dave Lowry \ Internet: (dlowry)
> >> To: gmclist \ Internet: (gmcmotorhome
> >> .org)
> >>
> >> Attachment: mimemsg.doc Code: 024D44L \ Created: Unknown [3 Kb]
> >>
> >> Subject: GMC: Thomas Compressor/Vacuum pump
> >>
> >> Now this is EXCITING!
> >>
> >> I'm still using the original Dana which is under the streetside bed in
> >> my '76 rear bath Royale. Either it's no good or the check valve is
> >> leaking, or both, so that the compressor cycles for 30 to 45 seconds
> >> every couple of minutes (even on "hold"), and it takes forever to raise
> >> the coach. Also, I want to add an auxilliary vacuum pump for the brakes.
> >>
> >> If I'm correctly understanding the recent thread, there's a good
> >> possibility I can replace the old Dana with a Thomas 315 or 317 to fix
> >> both problems. Here's what I envision:
> >>
> >> 1) Mount the new compressor in the engine compartment (where it wouldn't
> >> need a long power lead), together with the solenid valves & etc. (See
> >> note below) including a quick-connect fitting to inflate anything else
> >> that needs it.
> >>
> >> 2) Run a 1/4" copper pressure line back to where the Dana used to be,
> >> tying it to the check valve (I'll replace that too).
> >>
> >> 3) Run a 1/4" copper vacuum line to the brake booster, with the
> >> appropriate
> >> vacuum switch
> >> to turn on the pump when vacuum is needed.
> >>
> >> An added benefit for me would be that I could easily direct my mechanic
> >> to do the work.
> >>
> >> Note: If someone could PLEASE make the diagram and part numbers
> >> available for a pressure / vacuum system, I believe many could benefit
> >> by this moderately priced upgrade.
> >>
> >> Watching.
> >>
> >> Dave (& Dege), Santa Barbara, '76 Royale 26'
> >>
> >> -------- REPLY, End of original message --------
> >>
> >> --
> >> Gene 76Palm Beach /Or/CA
> >>
> >> GMC Technical Information
> >> http://www.california.com/~eagle/
> >
 
Ted,
Think about it for a second, "Your Air System Is An Important System"!
With out your air system working you do not get down the road! Believe
me you do not want the inconvenience of a developing leak.

J.R. Wright
GMC Greatlaker
77 Eleganza II
Michigan

>
> John, in general I agree with you. However I did add a copper loop
> to my air compressor outlet as shown on Gene Fishers home page to
> condense moisture from the air. Since the air system is not a crucial
> system I will chance the possible inconvenence of a leak developing.
>
> Ted Schurman
> 73 Glacier 73
>

> >
> > It seems like every so often we need to repeat the warning on the use of
> > copper tubing for RV use. Copper tubing has it place in short runs in
> > areas not subject to vibration, flexing and stress. This is extremely
> > important in the use of 1/4" copper. 3/8" copper tubing is more
> > forgiving. The best all around material to use in a motor home is the
> > polytube type and it is low cost even in the 3/8 size as compared to
> > copper. The only thing that you will see the truckers use is steel
> > lines and the polytube. Copper in air service will corrode and
> > contaminate your air system. Also the other standard warning for
> > fittings is that you NEVER use teflon tape!!! Only use the paste type!
> >
> > J.R. Wright
> > GMC Greatlaker
> > 77 Eleganza II
> > Michigan
> >

> > >
> > > -- [ From: Eugene Fisher * EMC.Ver #2.5.3 ] --
> > >
> > > sounds like you have some serious leaks. I just came back from another
> > > tuneup trip and after the inital pump-up I leave the switch on auto and
> > > the pump never comes on again. Your pump might be ok gene
> > > -------- REPLY, Original message follows --------
> > >
> > > Date: Saturday, 30-Jan-99 06:07 PM
> > >
> > > From: Dave Lowry \ Internet: (dlowry)
> > > To: gmclist \ Internet: (gmcmotorhome
> > > .org)
> > >
> > > Attachment: mimemsg.doc Code: 024D44L \ Created: Unknown [3 Kb]
> > >
> > > Subject: GMC: Thomas Compressor/Vacuum pump
> > >
> > > Now this is EXCITING!
> > >
> > > I'm still using the original Dana which is under the streetside bed in
> > > my '76 rear bath Royale. Either it's no good or the check valve is
> > > leaking, or both, so that the compressor cycles for 30 to 45 seconds
> > > every couple of minutes (even on "hold"), and it takes forever to raise
> > > the coach. Also, I want to add an auxilliary vacuum pump for the brakes.
> > >
> > > If I'm correctly understanding the recent thread, there's a good
> > > possibility I can replace the old Dana with a Thomas 315 or 317 to fix
> > > both problems. Here's what I envision:
> > >
> > > 1) Mount the new compressor in the engine compartment (where it wouldn't
> > > need a long power lead), together with the solenid valves & etc. (See
> > > note below) including a quick-connect fitting to inflate anything else
> > > that needs it.
> > >
> > > 2) Run a 1/4" copper pressure line back to where the Dana used to be,
> > > tying it to the check valve (I'll replace that too).
> > >
> > > 3) Run a 1/4" copper vacuum line to the brake booster, with the
> > > appropriate
> > > vacuum switch
> > > to turn on the pump when vacuum is needed.
> > >
> > > An added benefit for me would be that I could easily direct my mechanic
> > > to do the work.
> > >
> > > Note: If someone could PLEASE make the diagram and part numbers
> > > available for a pressure / vacuum system, I believe many could benefit
> > > by this moderately priced upgrade.
> > >
> > > Watching.
> > >
> > > Dave (& Dege), Santa Barbara, '76 Royale 26'
> > >
> > > -------- REPLY, End of original message --------
> > >
> > > --
> > > Gene 76Palm Beach /Or/CA
> > >
> > > GMC Technical Information
> > > http://www.california.com/~eagle/
 
John, not to carry this too far but that is why I have a new check valve
between the tank and the compressor, a schrader on the tank, ball valves
on each bag, schrader valves on each bag and carry a heavy duty portable
12V compressor. I think I have it covered. I meant that the air system
isn't crucial to safety. If the copper loop should develop a leak the
worst that will happen is that the pump might continue to run.
Ted Schurman
73 Glacier VA

>
> Ted,
> Think about it for a second, "Your Air System Is An Important System"!
> With out your air system working you do not get down the road! Believe
> me you do not want the inconvenience of a developing leak.
>
> J.R. Wright
> GMC Greatlaker
> 77 Eleganza II
> Michigan
>

> >
> > John, in general I agree with you. However I did add a copper loop
> > to my air compressor outlet as shown on Gene Fishers home page to
> > condense moisture from the air. Since the air system is not a crucial
> > system I will chance the possible inconvenence of a leak developing.
> >
> > Ted Schurman
> > 73 Glacier 73
> >

> > >
> > > It seems like every so often we need to repeat the warning on the use of
> > > copper tubing for RV use. Copper tubing has it place in short runs in
> > > areas not subject to vibration, flexing and stress. This is extremely
> > > important in the use of 1/4" copper. 3/8" copper tubing is more
> > > forgiving. The best all around material to use in a motor home is the
> > > polytube type and it is low cost even in the 3/8 size as compared to
> > > copper. The only thing that you will see the truckers use is steel
> > > lines and the polytube. Copper in air service will corrode and
> > > contaminate your air system. Also the other standard warning for
> > > fittings is that you NEVER use teflon tape!!! Only use the paste type!
> > >
> > > J.R. Wright
> > > GMC Greatlaker
> > > 77 Eleganza II
> > > Michigan
> > >

> > > >
> > > > -- [ From: Eugene Fisher * EMC.Ver #2.5.3 ] --
> > > >
> > > > sounds like you have some serious leaks. I just came back from another
> > > > tuneup trip and after the inital pump-up I leave the switch on auto and
> > > > the pump never comes on again. Your pump might be ok gene
> > > > -------- REPLY, Original message follows --------
> > > >
> > > > Date: Saturday, 30-Jan-99 06:07 PM
> > > >
> > > > From: Dave Lowry \ Internet: (dlowry)
> > > > To: gmclist \ Internet: (gmcmotorhome
> > > > .org)
> > > >
> > > > Attachment: mimemsg.doc Code: 024D44L \ Created: Unknown [3 Kb]
> > > >
> > > > Subject: GMC: Thomas Compressor/Vacuum pump
> > > >
> > > > Now this is EXCITING!
> > > >
> > > > I'm still using the original Dana which is under the streetside bed in
> > > > my '76 rear bath Royale. Either it's no good or the check valve is
> > > > leaking, or both, so that the compressor cycles for 30 to 45 seconds
> > > > every couple of minutes (even on "hold"), and it takes forever to raise
> > > > the coach. Also, I want to add an auxilliary vacuum pump for the brakes.
> > > >
> > > > If I'm correctly understanding the recent thread, there's a good
> > > > possibility I can replace the old Dana with a Thomas 315 or 317 to fix
> > > > both problems. Here's what I envision:
> > > >
> > > > 1) Mount the new compressor in the engine compartment (where it wouldn't
> > > > need a long power lead), together with the solenid valves & etc. (See
> > > > note below) including a quick-connect fitting to inflate anything else
> > > > that needs it.
> > > >
> > > > 2) Run a 1/4" copper pressure line back to where the Dana used to be,
> > > > tying it to the check valve (I'll replace that too).
> > > >
> > > > 3) Run a 1/4" copper vacuum line to the brake booster, with the
> > > > appropriate
> > > > vacuum switch
> > > > to turn on the pump when vacuum is needed.
> > > >
> > > > An added benefit for me would be that I could easily direct my mechanic
> > > > to do the work.
> > > >
> > > > Note: If someone could PLEASE make the diagram and part numbers
> > > > available for a pressure / vacuum system, I believe many could benefit
> > > > by this moderately priced upgrade.
> > > >
> > > > Watching.
> > > >
> > > > Dave (& Dege), Santa Barbara, '76 Royale 26'
> > > >
> > > > -------- REPLY, End of original message --------
> > > >
> > > > --
> > > > Gene 76Palm Beach /Or/CA
> > > >
> > > > GMC Technical Information
> > > > http://www.california.com/~eagle/
 
John,

I hadn't considered the corrosion issue when installing a length of
copper at the compressor exhaust port. Do you think the filter with
moisture bowl that is downstream from it would keep any corrosion out of
the rest of the system?

Richard
 
When I had my air system apart I noticed that a few of the fittings were
using the brass rings. There are no leaks at these fittings now, but is
there something about brass on the air tubing that makes them more prone
to working loose?

Richard

>....fittings come with a brass "wedding band."
>You don't use these, but you should buy nylon "wedding bands" and brass
>inserts for the plastic hoses

>Emery Stora
>77 Kingsley
>Santa Fe, NM
>
 
My brass fittings are 25 years old with no problems.
Ted Schurman
73 Glacier 73

>
> When I had my air system apart I noticed that a few of the fittings were
> using the brass rings. There are no leaks at these fittings now, but is
> there something about brass on the air tubing that makes them more prone
> to working loose?
>
> Richard
>
> >....fittings come with a brass "wedding band."
> >You don't use these, but you should buy nylon "wedding bands" and brass
> >inserts for the plastic hoses
>
> >Emery Stora
> >77 Kingsley
> >Santa Fe, NM
> >
 
Go to HOme Depot if you have one there and get a bottle of plumbing leak
detector. It is an orange liquid, syrupy consistency. Put it on each joint
and it stays there until you either wipe it off or it is washed off. it
will detect the minutest leak over several days if you want. Makes
beautiful bubbles!
Dave I assume you have a Power level system if you have a 1976 coach?

If you have the power level system with the large tank under the drivers
side of the coach, I would check the complete tank(you have to be very
thorough in doing it) and all fittings connected to it first. I found
several pin holes (under the mounting straps) in mine from rusting inside
out. If the tank is good and you still have the original check valve I
would get the Cinnabar upgrade consisting of a pressure gauge, stainless
steel check valve and water strainer. If you still have leak down, replace
the rubber o rings in the power level controls.

>OK. Now I'm less excited.
>
>First, I'll not use copper. (I knew that. Must have had "Senior Moment".)
>
>Sounds like I first need to find the leaks. Twice I've had my helper use
>the soapy liqiud without finding any, but it still has a very slow leak on
>the left side (3 or 4 days to fully settle) and the compressor cycles far
>too often while we're under way. I think I'm going to have to bite the
>bullet and let my high-priced mechanic try to find the problem (@ $60 per).
>Maybe if I study past posts to GMCnet and articles in Cinnabar's news
>letter and print some for the mechanic's use, he'll be able to find the
>problem before I run out of money.
>
>Questions: 1) Would a faulty check valve cause the compressor to cycle
>with the system on "hold"? 2) Where would be the best place to tie in a
>guage to monitor the pressure?
>
>After the leaks are eliminated, I'll deal with the slow pump-up by either
>having the Dana rebuilt or replaced with a Thomas 315).
>
>As for the auxilliary vacuum pump, I may have to buy a new one, as it's
>pretty difficult to pay someone else to scavange the right parts at the
>local junk yard. Again, I'll review past posts to learn more before I
>proceed.
>
>Sorry to be so long winded, but since I can't do the work myself, I need to
>minimize
>other's "research" time, and GMCnetters are are by far the best bunch to
>bounce ideas off of.
>
>While I'm at it, let me say that this site is a fantastic example of how
>the internet can be used to benefit the masses. I vote for NOT becoming a
>GMCMI chapter or envoking too many rules. GMCnet, despite minor disruptions
>, is an information resource and should be restricted to that.
>One-on-one social comentary should be conducted privately, and not on the
>GMCnet. Patrick, you had it right from the very begining; sharing
>information of common (GMC) interest. Period.
>
>I'm done.
>
>Dave, '76 Royale, Santa Barbara (sunny & 70)
>
>
>
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach
 
I installed the Cinnabar kit to filter air going into my air tank but I
don't think there is a filter following my air tank. After 25 years, It
probably contains plenty of rust, grit and so forth.

It seems a second filter / trap following the air tank would further protect
the air bag system, especially the valves.

I am thinking of adding one there similar to the Cinnabar supplied filter.

Would someone know of a better filter to follow the air tank ?

Don Miller
75 Glennbrook
Shenandoah Valley of Virginia
 
Richard,
I have a small coalescing filter between my compressor and air tank to
remove any moisture and dirt. Everyone likes to use the copper tubing
because it is easy to bend and work with, but it can reach out and bite
if you are not careful.

J.R. Wright
GMC Greatlaker]
77 Eleganza II
Michigan

>
> John,
>
> I hadn't considered the corrosion issue when installing a length of
> copper at the compressor exhaust port. Do you think the filter with
> moisture bowl that is downstream from it would keep any corrosion out of
> the rest of the system?
>
> Richard
 
Richard,
I use the Parker air fittings for polytube in my business and as I
rebuild by GMC. The brass ferrules that come with many of the
compression fittings are design to be used with copper tubing. Your
absolutely correct in using the nylon or plastic ferrules and the
inserts with the poly air lines. Use correctly the fittings are good
for 150# air minimun. I will scan the Parker Tech Data and post it soon.

J.R. Wright
GMC GreatLaker
77 Eleganza II
Michigan

>
> When I had my air system apart I noticed that a few of the fittings were
> using the brass rings. There are no leaks at these fittings now, but is
> there something about brass on the air tubing that makes them more prone
> to working loose?
>
> Richard
>
> >....fittings come with a brass "wedding band."
> >You don't use these, but you should buy nylon "wedding bands" and brass
> >inserts for the plastic hoses
>
> >Emery Stora
> >77 Kingsley
> >Santa Fe, NM
> >
 
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