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.

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?

Thanks for the link. I will take a look. This morning I decided to use the new tank I bought rather than "squirrel it away". I disconnected the air lines and removed the fittings from the old tank. I need to install the fittings, plug four (4) ports, and then it is ready for installation. I was going to powder coat it but will just install with "factory" paint. Hey the original one lasted almost 25 years. So the new one will likely outlast me. As with the RH tank, I will put a rubberized strap between the aluminum step and tank. My red knob does not pop out with the yellow knob so I think my system is functioning correctly. I was only guessing at the time delay but it is a few seconds before the trailer brakes release. Thanks everyone for the comments and information.

My trailer is a 2005 Great Dane single axle. When I pull out the yellow parking valve the trailer purges air and the red trailer valve does not automatically pop out. Also, I notice when I release (push in) the yellow parking valve I cannot move until the trailer brakes release. There is about a 3-5 second delay. Is this normal? New replacement (22QE31179M) tank bought from Barry but has several more ports and does not match exactly. I can make it work if I can't find a nice used tank.

We have a movie star...one of our own...can you guess who? https://www.youtube.com/watch?v=Gc6anukym9s https://www.youtube.com/watch?v=ENCQNfSIHuI

Barry - Great show (as always). And if it was not hot enough...there was the "flame thrower" that raised the temperature another 20 degrees or more. Did I miss the BMT nooner? Larry - congrats! You scored two (2) pics. If you need someone to spend the gift certificate...give me a call.

Air leak identified - LH air tank between tank and step...duh! I was not able to drive the "roll hauler" in a deep or cement pond so I got out the trusty water/soap bottle. Sprayed all the fittings and then soaked the tank at the step bracket (see photo). I put my ear to the area and even before the bubbles started I could hear a slight air leak. The bubbles confirmed what I suspected. So definitely in the market for a nice used LH steel tank. Still need an answer to my question...when parking the tractor-trailer combination, do I just pull the yellow knob and leave the red and blue knobs pushed in? The red knob states "Not for parking" so I never pull it when connected to the trailer. Thanks for the suggestions.

Have you checked the spray pattern of the nozzle? If it is burning in a small area outside the piston bowl, that might indicate a poor spray pattern.

Still looking for a nice used LH single chamber steel air tank (part number 22QE1269M or 22QE4907M). I will be at Trucktoberfest, Hagerstown Power Day, Winchester, and Gerhart's. Carl - I may need to contact Dave. Midway tanks are gone.

In June I replaced the RH (dual chamber) air tank because it was leaking air (red needle dropped quicker than the green needle and I could hear air leaking at the step bracket). In mid-July I noticed the green needle drops to zero (0) within an hour or so but the red needle stays above 100psi (after several days the red needle will eventually drop to zero but that is not my concern). I have three (3) hand valves - RED (trailer), YELLOW (parking), and BLUE (tractor). When I am connected to the trailer I only pull the YELLOW parking valve. When parking just the MH I pull the BLUE valve. When driving the unit, both needles stay together and drop pressure at the same rate. IIRC, the compressor kicks in at about 100psi and charges to 130psi. Using the drain valves, the RH tank secondary side has pressure but the primary side and the LH tank have no pressure. I also checked the trailer tank and it has pressure. First am I correct to only pull the YELLOW valve when parking the tractor-trailer combination? Second, I cannot hear any air leaks. I would think I could hear an air leak with the green needle dropping pressure so quickly. The other night I pulled all three (3) valves and the green needle dropped as before and red showed pressure. I am eventually planning to replace the LH (single chamber) tank but as I mentioned, I cannot hear any air leak. Any suggestions on where to look or what might be the issue? Thanks for any suggestions.

Larry, As I suggested, remove the hose on the inlet side and look at the fins. Pull the exhaust and look at the outlet too. Try "wiggling" the wheels to feel any sideways movement which would indicate bad bearings. Also look for evidence of oil on both the inlet and exhaust sides.

Truck is geared for 56 mph based on my calculations (4.62 ratio with 11R22.5 at 2100 rpm). Spicer TR722 5 speed transmission. How much to change axle ratio or OD tranny?

Does a bear shit crap in the woods? Count me in!