Just returned from a 500 mile trip. I noticed a change in the air up time of my brake system. It is taking a lonnnng time to air up, about 7 minutes from 0-120 and about 4 mins from 90psi (cut in) to 120. It used to be about 1 min from cut in to 120. The leak down is the same, about 36 hours back to zero when parked. I removed my air cleaner and checked the inlet pipe and I could feel suction on my fingers. When the dryer sneezed suction would cease. The coach loses about 10psi on a hard brake application. No noticable leak down holding the brakes with the engine off.
Something has changed and can't be good. The Eagle manual says I have a BW700 compressor with a D-2 governor. I don't know the age or time. However, I've had the coach since 2000 and put on 56k miles. Dryer desicant was changed about 20k miles ago.
I'm thinking a new compressor and governor may be in order just for the peace of mind.
Help.
David
The DOT test for compressor function is, with engine running, to fan the brakes down to below 85 PSI, and measure the time it takes the compressor to recover between 85 psi and 100 psi. The test fails if the compressor takes over 2 minutes and the vehicle must be taken out of service immediately (per the DOT). Normal time for the test is between 20 and 40 seconds. B
Vehicles with dual service air tank systems tend towards 40 seconds, my bus with a DD3 single service tank system takes 18 to 20 seconds. FWIW my bus takes close to 10 minutes from dead flat to 120.
There are various valves and shuttles inside the compressor and governor, you may get away with servicing what you have rather than just replacing, but it does sound like you have a problem somewhere. The key is that something changed. If it's working right it's the same every time.
Brian
David, check your auto drains on the tanks up front and the rear if the compressor is not pumping a lot of oil it is probably ok.
FWIW David the Bendix 700 is getting hard to find for a Eagle ,Jefferson is about the only show in town for that compressor
good luck
You have a leak in your aux air system (wipers, belts, shutters, etc). Get out the spray bottle and start spraying soapy water on all the components. Regulators, air valves, tanks, bleeders, tensioner cylinders, throttle cylinders, etc. Eventually you'll find a bubbler or two.
After I reread the original post, I agree that this is probably not a correct diagnosis.
if Gumpy is right and there is a leak in the aux system, then you should see the pressure leak down to about 60 psi quite quickly, then the pressure protection valve will kick in and the service tank would then leak down quite slowly. David said that over all leak down from full pressure was unchanged at 36 hours. If the bus leaks down at a reasonably steady state to zero, then there isn't a new and dangerous leak in the aux system.
you could probably hear a leak that caused the compressor recovery to increase from one minute to 4 minutes 90 to 120 psi, as soon as you turned the bus off and started snooping around, too.
Quote from: luvrbus on November 09, 2009, 03:58:49 PM
FWIW David the Bendix 700 is getting hard to find for a Eagle ,Jefferson is about the only show in town for that compressor
good luck
Do I have to replace it with a 700 or is there an alternate compressor that will bolt on to the 6v92?
Also, what price range am I looking at for parts? I can install myself.
David
David, I have never seen a replacment air compressor for a Eagle other than the Bendix Tu Flo 700 you can use a truck type but it requires new piping.
Jefferson charges around 500 bucks,and if you do change replace the compressor drive also buy it from DD.
It is not hard to do if you can still get into the engine hatch at the rear, you do have antifreeze and oil to contend with.
good luck and do you still have my number if you need help
I believe there is a new 700 on ebay for around $300 after shipping. It may be a 500 but it's worth checking out. keyword detroit diesel in the search and press newly listed. it just came on in the last day.
RB
I would do some more trouble shooting before springing for a new compressor. Perhaps a problem with the dryer causing some restriction in the line.
Rick, Eagle uses a different 700 compressors from most buses and trucks only the one for a Eagle will work without a lot of new piping I never understood Eagles reasoning for doing that way.
good luck
Could also be problems with the check valves between the air dryer and the wet tank, and the wet tank and the dry tank.
Brian
Since governors are so cheap($20+-), if yours uses the common type in use now, it is far better to start with replacing that before replacing the comp. The gov should be replaced anyway if you replace the comp.
I have a reman Bendix Tuflo 700 that I bought for my mc9, but it won't fit. A friend told me that he thinks it is for an Eagle. If you send me some photos or other identifying info, I'll see if it's what you need.
I pulled the compressor off. The coupling seems to be steel, not carbon fiber. I noticed there was no cotter pin in the slotted nut. Hmmm, could be bad. I also noticed the circle around the nut is rubbed clean. What does that mean? See the pictures:
The first and second and 3rd pictures are of the compressor with the drive cog slipped in
The 4th has the pencil pointing to the area around the slotted nut that is rubbed clean.
See next post below this one
3 more pictures
The first and 2nd are the drive cog slipped onto the engine
The 3rd is with it removed laying next to the mounting hole.
David if the drive is steel the compressor will have a key behind the drive check it and make sure it is not sheared if so find a compressor they shear for a reason.
good luck
I installed the new compressor and it leaks copious amount of oil at the bottom near the hole that drains oil from the compressor back to the engine sump. The instructions said no gasket sealant. I didn't use any. I haven't pulled it back off yet. I don't think I boogered up the gasket upon installation, but I did something wrong. Any ideas?
Another two hours of dismantling and reinstalling coming up. Arrrgh!
Edit: Update
I went back in and tighten the nuts, I mean tightened as hard as I could. The leak stopped. The Installation instructions say 220lbs torque. I did that much if not more.
The compressor model number to crossover to the old number is now Bendix 289941. Compressor cost me $423, governor, 15.99, and drive hub 31.33. Since I had to remove one bed to get this out it took me about 4 hours total to do the job. Bought it all at San Antonio Brake and Clutch.
This compressor will recover from 60psi to 120psi in about 30 -35 seconds at hiway speed, from 105 to 120 in about 10 seconds, so I definitely had a problem with the old one. It was taking about 60 seconds to recover from 90 to 120.
David
David, if the gasket was not a DD style gasket with the built in sealant ( orange or green etc) you need to use something I use aircraft Permatex
good luck
Quote from: luvrbus on November 14, 2009, 03:03:54 PM
David, if the gasket was not a DD style gasket with the built in sealant ( orange or green etc) you need to use something I use aircraft Permatex
good luck
The gasket had orange sealant on one side only.
David