Our '99 recently started showing higher then normal PSI readings on the front air gauge. Normal should be 90-120 psi.
Goes to 147psi before the pop off valve opens. Rear goes to 115-118 psi before the pop off valve opens.
Cycle the brake pedal 3 times reduces the front to 110 psi (rear to 85 psi) then back to 143 psi (rear back to 115 psi).
Note: these reading were in our driveway this morning, but on our recent trip, similar reader were noted. Current Odom is 108900.
What should I be looking for?
dick & Sue U320 '07 Escape toad, getting ready for a Northern & UP, Mich. trip in a few weeks.
Either the air governor has failed and needs replacing or sensing air line into the governor has broken off.
Have had both experiences.
The pressure goes up until the main pressure valve lets off the excessive pressure.
If the line has broken, you can hear it very easy when the engine is shut down,'
Good luck
Dave
The air compressor is located on the engine and operates only when the engine is running. Clean, filtered, turbocharged pressurized air from the intake manifold is force-fed into the air compressor. The compressor maintains the air system whenever the system's pressure falls below preset parameters. When the maximum pressure is reached, the compressor output is diverted. An air governor is used to maintain the air pressure from 85 to 125psi.
Air pressure build up test.Continue to let the air pressure build; it should not take more than four minutes for the air pressure to go from discharged (5-20 psi) to between 120 and 130 psi.
Governor cut-in/cut-out test.When air pressure gets between 120-130 psi, the
governor should cut out. The dash gauge needle stops moving. When the needle stops, pump the brake pedal to reduce the air pressure to 80 psi, release the brake pedal, the compressor starts pumping air (cutting in)! watch for needle movement. The air governor causes the air compressor to cut in between (85-90 psi).
Governor Service:
Haldex D2 Governor Service Data (http://www.beamalarm.com/Documents/haldex_d2_governor_service_data.html)
Sounds like the first thing I would check is the air governor. It is on the right side of the engine as you face it about halfway up. It has a cover over a screw that you can use to adjust the pressure. The bladder sometimes fails and if you do not have one you can screw it in and out and see if it helps. I carry one with me. You will need one that will turn on at 95 lbs. It is an easy fix.
Dave M covered the other possibilities.
I've been carrying this part around and really do not know what it is for. Is it the air governor?
It looks like an air check valve ??
Governor is a little bigger.
The rebuilt runs from about $15.00 to $30.00 outright, last one I purchased for my FT was from a
TSA truck stop, $25.00 and they installed it for $45.00 after they looked to see how hard it would be, they would have not done it if it were very hard. They were very happy.
My old governor became erratic, so I replaced it, now happiness.
Dave
Barry,
Would the haldex model in your picture be the correct one for my 99 U320?
I would not know that Part number for sure, but here is a photo of one on a 1997 to see if it looks like yours.
Thanks Barry. Mine is working ok. Would just like of get a spare. Will look at mine in the morning to see if it looks like either of your pictures.
I carry a spare but if you do not have one. You can take the rubber cap off and screw it all the way back then all the way down and try to get it back to where it was. I did that with Don Sprouse after a Rally we had in WV and he got home. He went and bought a replacement and a spare. In fact he go a deal and bought about ten of them so our mid Atlantic group was mostly supplied.
The Governor is refered to as the D-2 Governor, Mine is made by Bendix but there are most likely many brand names. They all are the D-2 Model
Ask any truck parts house for the D-2 and you have it, no matter who made it.
Dave
Thanks, I will ask for a D2 model.
Just a quick update and thanks for all of the input.
Our friendly Detroiter Truck Stop has D-2 Governors in stock @ $31.79.
He suggested that it could also be the gauge, so with that, I removed the air lines to the front gauge.
The gauge bottomed out at 30 psi, just about the amount that it read over normal range.
Several taps with the wrench and the needle moved to Zero.
Re hooked everything and now the front and rear track exactly each other and the pop-off is at 115 psi.
So now, either I have a defected or sticky gauge that needs to be replaced.
The manufacturing # is 150 077 006 and the VDO # is 150112. Just found one at Perry, Mi., almost on our way North for $32.50.
Monday morning I'll be at my parts store to buy a spare governor, just in case.
Once again, thanks for all the help.
dick & Sue, heading for Northern Mich and the UP starting next Sat.
In an earlier comment, July 30th, you had mentioned the pressure went up and the pop off relief went off. If that is the case, I can not see where the gauge was all that incorrect.
Of course something else could have caused the sound of the pressure relief going off like a high speed leak in a tire. air conditioner line blowing off. :D
Cheers
Dave
Dave,
What I said was "Rear goes to 115-118 psi before the pop off valve opens." May be I should have said that when the pop off goes off, the front gauge was at 147 and the rear was at 115-118 at the same time.
Since removing the air lines from the front gauge and "tapping" the gauge back to zero, both gauges tracked each other on a restart. During this test, we were parked in our driveway, no tire leak & no AC on.
Just rechecked a few minutes ago, both gauges were in sync with each other at 60 psi.
We have located a new VDO gauge and the D-2 governor (keep as a spare). Will pick them up this week.
Thanks for input. I always like to go back and recheck what I did, just the old "engineering" in me.
dick
Dave, most off over pressure pop off valves go off about 140-150 psi.
Looks like the first step would be get a good working governor installed, then check out where you are with the gauges.
It is always nice to have a solid starting point from where you can make all your calculations.
I read that some where in the engineering books
Had it happen due to sensing line to governor had broken off while on I-95 is FL. Fixed at first rest area.
Good luck
Dave
Dave,
Thanks for the update. That'll be my new plan. So much easier to repair in our driveway than on the road side.
dick
Found a Governor for $16.93 at http://tinyurl.com/2fj554o (http://tinyurl.com/2fj554o)
Barry, Yup, the D-2 governors have been in the $15-$30 range for years. And they are real simple to replace, if you have the right tools and some mechanical sense. Not "Rocket Science"
Dave
I was just offering to Dick where he could find one cheaper than the one he is looking at.
Barry,
How do I know if my Bendix system uses the D2 Governor? Is it pretty universal, even for old (19 years) coaches like mine? I really like the price from Ryder Fleet products and have purchased from them a few times before.
This is a photo of my air governor. Hmmm, guess i will have to do something about that rust.
Don, Take a look at D2 on the Internet and look at yours. If they are similar, you have a D2. http://www.google.com/images?num=100&hl=en&rlz=1Q1DLUS_enUS354US354&q=d2+governor&um=1&ie=UTF-8&source=univ&ei=UkZWTOy3DsX_nAfVyfSUBA&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CDIQsAQwAw (http://www.google.com/images?num=100&hl=en&rlz=1Q1DLUS_enUS354US354&q=d2+governor&um=1&ie=UTF-8&source=univ&ei=UkZWTOy3DsX_nAfVyfSUBA&sa=X&oi=image_resu)
Not for the "mechanics" at the TA Truck Stop in Brunswick, Ga. It was not a D-2 governor, but it was very similiar but had extra air outlets and was one of the Bendex governors replacing sob. They said it would not fit. I had to show them how to install it and plug off the extra outlets, cause they were clueless. Then they charged me labor. I should have charged them for instruction time. Too boot, they paged me from the restaurant when I was eating, and when I got back there, my meal was gone. It was one of those days.
If it was not a D-2 governor what was governor did you use? Part Number?
Not a clue, only ever used the D-2, so who knows what could be gotten out of the wood work??
Might be a very old prior to the D-2, who knows.
I will ask my supplier about this tomorrow and let you know. Maybe the SOB can provide a pix of this jewel.
Luck
Dave
Bought a D2 haldex air governor at NAPA for $14.02. Looks just like the one on my coach. Will probably never need it now that I have a spare.
Our D-2 type of governor had an open female threaded hole, used as a vent to the air.
I felt dirt, water, etc could enter the governor, so I screwed in a brass hose barb fitting into the vent hole and ran about a couple of feet of rubber hose down that is open at the bottom end.
Concerning the air compressor D-2 governor,
After checking with 3 local supply houses, the word seems to be the D-2 made by lots of outfits, Bendix, Midland and others, is the only governor they see EXCEPT for some foreign truck systems.
The D-2 is very versatile, capable of many different setups including the alcohol injection or pop off the air dryer.
Lot of ports / positions/ options.
Because of the different setups possible, it is REAL important to match the holes with the old unit or you can create a crazy, not operating correct system.
Have a ball
Dave
Dave,
Did you see this post I saw elsewhere? The last paragraph tells all.
"I work on the tech team at Bendix and I've read some disturbing things throughout this thread. First of all, 150 psi is the MAX rating for every Bendix air brake system component (same for all brands). So it is not ok for a system to be running that high.
Second, when adjusting a governor, turning it CW will decrease the pressure. CCW will raise it.
There are many misconceptions when it comes to the air dryer. The rule of thumb is that if you are not dumping air from the purge valve while trying to build to system pressure, which means you are stuck on the side of the road, it's probably NOT an air dryer issue. 90% of the time it's the compressor unloaders that are faulty and unfortunately, all the noise is at the dryer. The governor and dryer most often get changed first without success.
In this situation, if the air dryer never makes a single noise until 140 psi, then I believe the governor is set too high or gauges are off. Put a gauge in either the "res" port on the governor or the "wet" tank (1st tank the dryer delivers to). That is the pressure that the governor is making its decisions off of.
I can count on one hand in my 12 years of being an air brake expert where the governor was actually the problem. But that's only with Bendix governors. I can't count the amount of times that knock off governors (overseas cheap junk) malfunction and cause issues in the system."
It was on a Peterbilt with a big Cummins under the doghouse. And a very long time ago, so my memory is lacking at to the model of the governor. But the other brand was a Airco which was throw away junk.
PatC,
I would never leave coach at any truck stop for work while I had lunch. I have also had issues with TSA shops even while I am watching them.
It just proves that just because a person says they are a mechanic, does not mean he knows any thing. And yes, a simple governor has baffled many wannabee mechanics with too many pipe plug holes and not enough pipe plugs.
;D
Dave