MH Air Leak

[farmer52]

16 minutes ago, AZB755V8 said:

I would say that a 4psi drop an hour is Great!

I am loosing air at the rate of ~15psi per hour sitting and 60+psi per hour driving.

[gearhead204]

Ken chalk the wheels and release the brakes then feel around the air cans (double chambered only) and see if any air is escaping from the bleed holes.

 I'm thinking maybe you have two problems and a blown maxi diaphragm could be your moving (driving) air leak. and then a smaller one for the other loss.

Also have you removed the compressor discharge line to make sure air isn't bleeding back thru a bad check valve in the primary air tank?

 

Edited September 6, 2016 by gearhead204

[farmer52]

15 minutes ago, gearhead204 said:

Ken chalk the wheels and release the brakes then feel around the air cans (double chambered only) and see if any air is escaping from the bleed holes.

 I'm thinking maybe you have two problems and a blown maxi diaphragm could be your moving (driving) air leak. and then a smaller one for the other loss.

Also have you removed the compressor discharge line to make sure air isn't bleeding back thru a bad check valve in the primary air tank?

 

Rob,

Thanks for the suggestions on what/where to check.  I will try to check them this week before I leave for Allentown or Friday when I am at the Museum for Trucktoberfest.

FWIW, I had this issue (leak down while driving) before both tanks were replaced.  I have not noticed any change in the leak down rate since.  Although both tanks were in "poor condition", I was hoping my air leak was resolved when changing the tanks.

[AZB755V8]

4 hours ago, farmer52 said:

I am loosing air at the rate of ~15psi per hour sitting and 60+psi per hour driving.

Oops, I misread that 20psi after 6 hours.

Rob, thanks for pointing out, air leaks at some of the less obvious locations. I will have to check some of those on my truck, it sure would help to get some of my leaks stopped too.

 

[BC Mack]

Kn

what Gearhead said....

build air to max with brakes off (blocked!) and shut it off...

check for leaks at the maxi's park side (air pressure is holding the brakes off) check for leaks in the housing or drain hole...and the QR valve..

have someone make a full brake application, when stabilised no more than 3psi per minute air loss is allowed, again go around and check for leaks.... before your helper's leg spasms..!!

build up the air, shut off, open up the discharge line out of the compressor and bubble check, the SC-3 non return valve on the wet tank end should hold the air in, if not, it leaks back into the compressor and out the inlet side.

at least your D-2 governor seems to be good if it cuts in-out at about 25psi spread, it can be adjusted for max but not spread.

even the airbags and valve on the cab should be static checked too...

if the loss while running is not due to brake applications or cab then you have a malfunction that needs to be found...

and while you're at it, ensure the low air alarm works on both systems... and that test will check the pressure protection valve too.

BC Mack

[farmer52]

Thanks Rob and Sean for the diagnostic info.  Not sure if I will get it done this week before I leave for Trucktoberfest.  It is only me, myself, and I but will do my best to check things and report back with the results.  Maybe I can enlist the help from someone at the Museum on Friday.  Hmmm, wonder who that might be?  And I will take a spray bottle of soapy water with me.

BTW, I don't think there is a check valve between the compressor and primary air tank.  The parts book does not show one.  I will know when I break the line at the compressor.

The low air alarm works, at least when building air pressure.  I think the buzzer goes off about 60psi.  I will confirm on the down side.

I just hope the leak is obvious and simple to repair.  I would add "cheap" but that may be too much to ask.

[farmer52]

I think I found the cause of my air leaks.  First there is to be a check valve in the line from the RH primary tank to the LH tank (at the LH tank).  I cannot see one, unless it is an internal check valve in the line.  That might resolve my "parked" leak down.  Now for the big one, my moving leak (hopefully) is at the trailer gladhand port on the trailer.  I replaced the gladhand seals but there is still a major air leak behind the clamping mechanism (don't know the correct nomenclature).  Is there a gasket/o-ring between the stamped steel bracket and casting?  If so is it replaceable?  Or is the glandhand seal the "gasket"?  I searched the Great Dane parts catalog and Sloan but I do not see anything concerning a gasket/seal.  Anyone know what I am talking about?  Or do I need to replace the complete "port" on the trailer?  See attached pic, do I need to loosen two (2) torx screws and reposition the gladhand seal?

UPDATE: Being the inquisitive engineer I could not sit back and do nothing.  So I removed the torx screws and the hex bolt (at the top of the picture).  This allowed movement of the red bracket but not able to remove (round head rivet at the bottom of the bracket).  But I could see behind the bracket and there is no gasket.  I removed the gladhand seal, cleaned the casting and seal, used white lithium grease, and reinstalled the seal and screws/bolt...NO LEAK.  So now comes the road test on Friday.  Stay tuned for the continuing saga of "Roll Hauler Express Air Leaks".

BTW, I checked the tractor brake cans and there are no leaks.  In all the "excitement" I forgot to check the trailer.  I will do that on Thursday.

[farmer52]

On ‎9‎/‎5‎/‎2016 at 10:11 PM, BC Mack said:

 

have someone make a full brake application, when stabilised no more than 3psi per minute air loss is allowed, again go around and check for leaks.... before your helper's leg spasms..!!

Sean,

I did a full brake application for about five (5) minutes (my leg was getting tired) and the needles never moved.

[farmer52]

Success at last!!  I installed a check valve (Bendix 800376) at the LH tank inlet.  The air pressure this morning (both primary and secondary needles) is 80psi, down from 125psi.  I calculated the air leakage and it is about 3psi per hour.    Saturday will be my "check" on the running air leakage (compressor cycling) during my bouncy trip (without trailer) to Hagerstown, MD.

[farmer52]

Drove the MH (bobtail) to Hagerstown, MD to participate in Power Day.  From Breezywood to Hagerstown (about 55 miles/1 hour) the air pressure never dropped from 130psi.  So life for the MH is good!  BTW, Power Day was great.  Thursday will be a run to Winchester with the trailer.

[DCR]

So Ken, you are saying you are full of air??

[farmer52]

9 hours ago, DCR said:

So Ken, you are saying you are full of air??

Yea, hot air!

[farmer52]

Well the air leak saga continues.   On Wednesday afternoon I installed a check valve at the inlet of the wet tank.  Thursday morning before I left for Winchester, NO AIR IN WET TANK!  It leaked down overnight even with the check valve.  I pumped up the air and did a quick soapy water check but did not see any bubbles.  Driving to Winchester, the air compressor cycled every 10 minutes.  So I concluded I STILL have an air leak with the trailer connected.  Today (Saturday) before I departed Winchester, I pumped up the air and did a more thorough check with soapy water.  No bubbles at the check valve tank connection but saw some bubbles at the trailer air supply gladhand.  I did not hear any air leaks at the back of the trailer (brakes or air bags).  I checked the gladhand seal and reattached the gladhand making sure it was snug.  On the return trip to the farm, the air did not leak down as rapidly.  I estimate at least 30 minutes between cycles.  Need to try different gladhand seals but still puzzled why the wet tank leaks down even with a check valve.  Stay tuned...

[Outbehindthebarn]

On 8/22/2016 at 3:08 PM, Vladislav said:

Build up the pressure than drive the truck into water with all air components under surface and than watch for bubbles ??

Russian deadpan humor... l almost fell out of my chair laughing.

[Hobert62]

Going down the fine PA roads with an air ride outfit and the air compressor cycles  every :10 minutes doesn't seem bad at all. Atleast in my opinion.  I apologies if I miss read something but if its windy an air ride cab can drain the air tanks parked overnight.   

Edited September 25, 2016 by Hobert62

[farmer52]

16 hours ago, Hobert62 said:

Going down the fine PA roads with an air ride outfit and the air compressor cycles  every :10 minutes doesn't seem bad at all. Atleast in my opinion.  I apologies if I miss read something but if its windy an air ride cab can drain the air tanks parked overnight.   

Never thought about the cab air bags.  But that does not explain why the wet tank leaks down within a few hours (even with a newly installed check valve).

Can anyone recommend good quality gladhand seals?  Or are they all the same.  I been using white lithium grease on the seals.

[gearhead204]

sugary  Tabaco  laden spit seems to make the best seal between the two glad hands  as for the nylon or rubber glad hand seals or a mixed combination , well I guess to each their own. when dump trucking I always carried the nylon ones as we hooked and dropped 5-10 times a day, on the trailers that stayed coupled up I would run the rubber seals ( mostly because that's what they came with)    

[Hobert62]

I've also used the red and blue ones, black rubber ones, a combination of both.    I think I have a fancy orange one now that I have no idea where it came from.  If the glad hands fit together to loose some times you have to bend the outer steel peice a little to hold them together tighter.  Where does your check valve on the wet tank go? I'm assumeing  it's between  the wet tank and supply tank.   Is it leaking out of your exhaust on your air dryer? When my dads dryer went bad his leaked from there.  I don't have an air dryer on my B and mine bleads back through my compressors air intake a little when I first shut the truck off.    I haven't look into it yet but I'm guessing there is a sticky valve in the aircompressor head from sitting for so long.    

[farmer52]

2 hours ago, gearhead204 said:

sugary  Tabaco  laden spit seems to make the best seal between the two glad hands  as for the nylon or rubber glad hand seals or a mixed combination , well I guess to each their own. when dump trucking I always carried the nylon ones as we hooked and dropped 5-10 times a day, on the trailers that stayed coupled up I would run the rubber seals ( mostly because that's what they came with)    

I don't do tabaco, will plain spit work?

10 minutes ago, Hobert62 said:

I've also used the red and blue ones, black rubber ones, a combination of both.    I think I have a fancy orange one now that I have no idea where it came from.  If the glad hands fit together to loose some times you have to bend the outer steel peice a little to hold them together tighter.  Where does your check valve on the wet tank go? I'm assumeing  it's between  the wet tank and supply tank.   Is it leaking out of your exhaust on your air dryer? When my dads dryer went bad his leaked from there.  I don't have an air dryer on my B and mine bleads back through my compressors air intake a little when I first shut the truck off.    I haven't look into it yet but I'm guessing there is a sticky valve in the aircompressor head from sitting for so long.    

I am using the red and blue nylon seals with the stainless steel screen insert.  The supply (red) seems to be loose.  I will try tightening the clamp.  I do not have an air dryer.  Truck was not spec'd with one.  I have a check valve at the wet tank inlet with the SS line from the compressor connected to it.  The wet tank leaked down within a couple hours before the valve was installed and it STILL leaks down.  The LH tank has a check valve at the inlet port and the line from the wet tank is connected to the valve.  I am not loosing air in the secondary or LH tanks overnight.  MOF, the pressure after two (2) days was about 70psi.

[farmer52]

Final update for 2016...

Bent the gladhand "retainer" on the trailer.  Seems to fit tighter.  Checked the compressor supply line fittings and no leaks.  Also checked the governor "feedback" line and no leaks either.  The Roll Hauler goes into winter storage on Thursday.  So no more checks/updates until 2017.

Thanks to all for your suggestions to resolve the leaks.

[j hancock]

Hope you are gaining on it.    Interesting..... I thought for sure you used the MH for Christmas shopping trips.

[farmer52]

9 hours ago, j hancock said:

Hope you are gaining on it.    Interesting..... I thought for sure you used the MH for Christmas shopping trips.

Yes, made headway on the leak issue.  This year I replaced both air tanks and installed some check valves but wet tank still leaks down.  Otherwise holds air in the secondary and main tanks.  Did not hold air before.

My Christmas list is short and I don't need the MH for a couple lumps of coal.  It spent 20 years outside and running in the snow and salt so it deserves a covered resting place during the winter months.  Now if I could only find a shed for the trailer.

[fxfymn]

Ken, you are making me chuckle as you try to chase down this ghost.

We had a 1969 C cab Ford rescue squad that leaked air right from the git go. It went to the shop more times than we could count and they never could find the leak. It got to the point that we threatened to drive it into the Potomac river to look for bubbles (the shop was not amused by this suggestion).  We finally jury rigged a double male quick connection to plug into the auxiliary air outlet so we could keep the station's air compressor plugged into it to keep the air pressure up. 

Point is you may never find all of the leaks. DOT has a rule on leak down rate which I'm sure someone on here will be able to quote. If it passes the DOT test you may just have to suppress your "anal" gene and live with it.

[farmer52]

Roll Hauler is hibernating for the winter.  Filled the tank with fuel and connected the battery maintainers.  As I mentioned, no more air leaks this year.  Not concerned as long as the air stays up while I am driving.  I am just a frustrated old engineer.  I drove it over five (5) years with "major" leaks.  2017 will be its 25th birthday so I am going to put Historical plates on it.  Then hopefully I will not need to be concerned about the DOT.

[gearhead204]

when I worked at the local apple warehouse we had a 79 f 800 single screw tractor would hold air for over 10 months, always was amazed when I would turn the key on and the low air buzzer would not come on, would look over at the pri.sec. needles and both were still above 110!