Miriam Romero Posted April 16, 2021 Share Posted April 16, 2021 (edited) Im at the end of my rope! 2012 Mack red engine MP7, rebuilt Wabco Compressor, new governor, working dryer but not sufficient enough air. It takes me 5 mins of 1600rpms to build up to 90psi. If I lower the rmp's, it goes down to 50 psi. no leaks. The primary tank is stopped up but I don't know with what. I bypassed the primary tank and air dryer and still can only get 90psi. This truck sat for 2 years so I'm thinking maybe oil was in the tank and dried out? Ive never experienced this problem before. My mechanic can fix anything and he is stumped... Any suggestions would be greatly appreciated. Edited April 16, 2021 by Miriam Romero Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/ Share on other sites More sharing options...
Hayseed Posted April 16, 2021 Share Posted April 16, 2021 I would Check that the Airline from the Compressor to the Wet Tank isn't carboned Up.. 1 1 Quote "Be who you are and say what you feel...Because those that matter...don't mind...And those that mind....don't matter." - Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472562 Share on other sites More sharing options...
Swishy Posted April 16, 2021 Share Posted April 16, 2021 yahr wot seed sed we have a mack th@ passes a bit of oil down to the 1st tank, the oil n heat carbonizes n clogs up the main pipe th@ restricts the air flow also if U drain all the air tanks n put the shop air in the 1st tank n see n listen to where the air is go n cya 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472566 Share on other sites More sharing options...
Miriam Romero Posted April 16, 2021 Author Share Posted April 16, 2021 5 hours ago, Swishy said: yahr wot seed sed we have a mack th@ passes a bit of oil down to the 1st tank, the oil n heat carbonizes n clogs up the main pipe th@ restricts the air flow also if U drain all the air tanks n put the shop air in the 1st tank n see n listen to where the air is go n cya Thanks, I will try that! Im hoping its not the New/rebuilt compressor. Those things aren’t easily accessible. thanks for your suggestions! miriam Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472575 Share on other sites More sharing options...
Miriam Romero Posted April 16, 2021 Author Share Posted April 16, 2021 6 hours ago, Hayseed said: I would Check that the Airline from the Compressor to the Wet Tank isn't carboned Up.. I will do that! Thanks for commenting. I’m at my wits end with this! 30+ years in trucking, married to a Mack specialist who’s mentor is a Mack teacher and they are stumped! I guess computers can diagnose and fix everything🤷♀️ thank you for your suggestion! I will check that line! Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472576 Share on other sites More sharing options...
Swishy Posted April 16, 2021 Share Posted April 16, 2021 IF U suspect the new compressor is not up to scratch U could use a stethoscope to hear wots go n on the ozzie bush stethascope = a long handle screwdriver place end on compressor with engine running place thumb on end of screwdriver handle place ear on thumb WotSezU? cya 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472588 Share on other sites More sharing options...
carlotpilot Posted April 16, 2021 Share Posted April 16, 2021 worth checkin old mh we have was giving me same kind of greif . it turned out to be the airhorn valve leaking through not enough to blow the horn or even hear from the ground but was enough to cause exactly what you`re describing 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472590 Share on other sites More sharing options...
Hayseed Posted April 16, 2021 Share Posted April 16, 2021 17 hours ago, Miriam Romero said: The primary tank is stopped up but I don't know with what. I just noticed This ^^^^ it needs to be sorted our First.. In My opinion.. 1 Quote "Be who you are and say what you feel...Because those that matter...don't mind...And those that mind....don't matter." - Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472591 Share on other sites More sharing options...
Miriam Romero Posted April 17, 2021 Author Share Posted April 17, 2021 5 hours ago, Hayseed said: I just noticed This ^^^^ it needs to be sorted our First.. In My opinion.. We are going to try all of these suggestions tomorrow. We have a tiny Snap On camera On a wire that’s we are going to try to send into the primary tank. thank you all for taking the time to comment and suggest on my dilemma. I will report back on our findings. Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472602 Share on other sites More sharing options...
Popular Post Miriam Romero Posted April 17, 2021 Author Popular Post Share Posted April 17, 2021 Ok, we hooked shop air up to wet tank and it is still very slow to pressure up. We were able to get it to 130psi after 4-5 minutes. Now we take the tank off to see better. We pour out some brownish water that would come out the petcock valve. We see a screened filter on one side so I’m assuming it’s a check valve? So, I can’t see anyway to fix this except buy a new tank. They have one in Mississippi and I’m in Houston Texas. They won’t take my card over the phone so Monday morning...off the Vanguard Mack! At least everything in the “compressing” air system will be new Thanks for everyone’s input! it did give me more things to look for. it’s not over yet but I think the new tank should do it.🤞 2 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472633 Share on other sites More sharing options...
Miriam Romero Posted April 25, 2021 Author Share Posted April 25, 2021 Well crap, the new tank didn’t solve it. I don’t know what to do! it holds at 80psi with engine at 1000rpm never have experienced this trouble. Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472904 Share on other sites More sharing options...
Swishy Posted April 25, 2021 Share Posted April 25, 2021 plumb the compressor up to the 2nd tank .... bypass the 1st tank n C wot happens cya 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472907 Share on other sites More sharing options...
High Binder Posted April 25, 2021 Share Posted April 25, 2021 Just my two cents worth, you're assuming the new governor and the compressor you put on are good. I would first replace the governor, maybe the compressor, and find your air leak. We've had to replace a lot of new and reman parts lately. Your pressure drops from 90 to 50 when your rpm's drop. Where's the 40 lbs of pressure going? JMO 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472908 Share on other sites More sharing options...
Miriam Romero Posted April 25, 2021 Author Share Posted April 25, 2021 Thanks, we just found it! It’s an air hose collapsing when it heats up. We were able to make up a hose to try it. It’s working! I’ll go Monday and get the right hose. again, thanks for commenting. We did use all of your suggestions! Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472910 Share on other sites More sharing options...
Swishy Posted April 25, 2021 Share Posted April 25, 2021 Hose from compressor to 1st tank needs 2 B made of something th@ can withstand heat eg: Copper pipe ....... or ........ stainless steel braded flexible covered hose cya 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472911 Share on other sites More sharing options...
Miriam Romero Posted April 25, 2021 Author Share Posted April 25, 2021 My husband said that he could blow through it until it heated up and it would swell up inside of the hose once heated and he couldn’t blow through it. The only place open 24/7 that may by chance have that braided hose is Freightliner in Houston. This tank has fine metric threads and I’d bet that Mack is the only place to get it. The new air tank had an extra hole so we had to get a plug from Mack this morning. Thanks again! I’m grateful for your input. I do believe we are back in business...with a whole new air brake system😂 Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472912 Share on other sites More sharing options...
High Binder Posted April 25, 2021 Share Posted April 25, 2021 Glad you found the problem. That's a first for me since I've never had the main line collapse. My trucks are older and still run hard lines off the compressor. I learned something. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472918 Share on other sites More sharing options...
Rob Posted April 25, 2021 Share Posted April 25, 2021 I always run type "K" copper pipe for the discharge of the air compressor to the drier, or wet tank. This is a heavy wall type copper pipe and work hardens when you bend it but excels at both cooling the discharge air from the compressor, and condensing out the moisture due to the cooling effect. Don't attempt to bend type "K" pipe by hand as it will readily kink in the bending area. I've seen the newer "teflon" stainless braided discharge hose used a lot and it works well but is expensive; albeit much easier to run. Anything needs support and both types require supporting that will preclude "drooping" or vibration to keep from moisture "pooling" in the line which will cause "slugging" of the output air. 2 Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472925 Share on other sites More sharing options...
Miriam Romero Posted April 25, 2021 Author Share Posted April 25, 2021 I am relaying all of your suggestions to my husband who has been a Mack mechanic for over 30 years. I’ve never seen him stumped until this. Thanks again, I appreciate you guys! my puppy’s got her pep back!😂 btw, I’m the driver and my hubs is the mechanic...it works for us😊 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472933 Share on other sites More sharing options...
Mark T Posted April 25, 2021 Share Posted April 25, 2021 don't forget as Rob said it needs to be supported that requires teflon P clamps as well to put up with the heat 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-472943 Share on other sites More sharing options...
Polarhound Posted April 29, 2021 Share Posted April 29, 2021 On 4/16/2021 at 5:15 AM, Swishy said: we have a mack th@ passes a bit of oil down to the 1st tank, the oil n heat carbonizes n clogs up the main pipe th@ restricts the air flow This is also why it is so critical to use a proper coalescing air dryer cartridge on US07 and newer engines. Too many people try to save a few dollars by using older style non-coalescing cartridges or not changing them on time (once per year). Failing to maintain it risks not only clogging up the tanks, but screwing up your entire AHI system. From MTPI 561-016: Note: Proper servicing of the air dryer with an oil coalescing media cartridge is critical to the Aftertreatment Hydrocarbon Doser (HC Doser) system. The HC Doser system uses compressed air to purge fuel from the HC Doser nozzle supply pipe and the HC Doser nozzle. This air is also used to continuously cool the HC Doser nozzle and to prevent soot from the exhaust entering the HC Doser nozzle. The removal of oil from the compressed air system is critical to support the function of the air control solenoid valve in the HC Doser dosing module. Oil in the air supply can collect in the valve and cause it to stick, inhibiting the function of the valve. Additionally, oil in the air can collect on the HC Doser nozzle and form deposits which can reduce HC Doser nozzle flow. Coalescing Air Dryer Cartridges should be serviced and replace every 12 months during normal preventive maintenance. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66551-i-give-up-air-compressor-system-trouble/#findComment-473130 Share on other sites More sharing options...
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