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.

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.

My favorite bus is the GM Greyhound Scenicruiser. Second favorite is the Crown bus especially the tandem axle buses. And why didn't Mrs. FWD "doll up" for the Nunnery?

October in PA = possibility of sleet, ssssnow, and salt.

Excellent show and venue. Too bad it was so stinkin' hot but at least the A/C in the museum was working. Kudos to Doug and the Museum staff for their efforts. Always something "new" to see at the Museum.

Affirmative...I plan to arrive around noon on Thursday and depart Saturday afternoon. Going to "rough it" and sleep in the trailer both nights. Not sure if Capt. Barry will be there. You all missed a great Trucktoberfest on Saturday. But it was HOT!

If you license it as an "antique", most states restrict the usage (i.e. parades, shows, etc.) but cannot be used "for hire" or commercial service. Check with your state BMV to be sure.

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

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.

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.

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.

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

T2050 transmission so no range piston. Yes the HVAC doors are air operated. What about the issue of loosing more air while I am driving (~30psi in 20 minutes =1.5psi per minute)? Sitting the air leak is way less at approximately 0.27777psi per minute. Or should I just say "fluff it" and move on?

Went to the Shortway Truck Show; Washingtonville, PA on Saturday, nice turnout of trucks and show (great ice cream BTW). The primary air (green needle) after six (6) hours sitting was down to about 20psi (secondary red needle at about 90psi). So still have an air leak. Someone mentioned perhaps the brake "cans" are leaking. Does this make sense while the truck is parked? Is there an easy way to check them? Soapy water? Any particular area to spray? I replaced the dash valves last year and there are no leaks there. Guessing it is outside somewhere since I cannot hear air leaking. Also while driving the air will drop (both needles at the same rate) from ~120psi to 90psi in 20-30 minutes (then the compressor kicks in and recharges). Thanks for any suggestions/help.

Yea, I was curious who was the "crazy biker" trying to pass me. I did not remember pulling out in front of anyone. Sorry I did not have more time to talk. I wanted to get south of State College before the Pedo State game was over.

FWIW When I pull the yellow knob, I get a "puff" of air from both the tractor and trailer. But the red knob does not pop out.

Back in Black Al?

David, Some older pics are in my gallery http://www.bigmacktrucks.com/gallery/album/1033-1992-mh612/

In the past I been referring to my MH as the "spudmobile" since it was previously owned my Martin's Pastry makers of Martin's Potato Rolls. Fxfymn calls it the "roll hauler" so I renamed it the "Roll Hauler". Thanks Carl for the "catchy" name. I had some lettering made with the new name...

Replaced the new (22QE31179M) LH tank this afternoon. Still have an air leak somewhere but is dropping slower than with the old tank. I checked all the external fittings with soapy water but no bubbles. I am done for this year trying to resolve air leaks. Attached pics of the old tank and the new installation.

Bob, Thanks! At first I thought it was a snow thrower then realized it is a reel mower. Looks easier, simpler, and probably less expensive than working on a Mack truck.

A question for the Mack Museum and its staff to answer. Wasn't the Gen I Superliner manufactured in Hayward? Did Hayward have a design studio?