Bendix Air Dryer

[Bus'n it]

So I'd like to replace my air dryer as it is original to the bus and one of the copper lines running to it wiggles. Someone put a piece of foam and electrical tape around the flare joint. And they say buses are well maintained...Sheesh. I called my local BB dealer and they did confirm it is an AD-9 dryer but said something is different about it and couldn't elaborate. Either way they want $510 for it. I find genuine Bendix AD-9's online for between $350-400. What could be different about these things? Any brake gurus here?

[s2mikon]

Check evil-bay and amazonk.

[Bus'n it]

I did, but they have Chinese knock offs. I would still prefer to buy OEM. I don't want to crawl under there again! (Especially with the new storage area killing space.)

[s2mikon]

I saw bendix and haldex at half the bluebird price. I wouldn't buy Chinese.

[s2mikon]

Part #: MBI 65650 NAPA 230 dollars.

[Bus'n it]

The BB guy is telling me it has some ID number of 88562 which is what makes it different. The only thing I see different on mine is the label is facing towards the front whereas the main line in is to the left.

[mmoore6856]

Originally Posted by Bus'n it

The BB guy is telling me it has some ID number of 88562 which is what makes it different. The only thing I see different on mine is the label is facing towards the front whereas the main line in is to the left.

ad 9 air dryers are rebuild-able by anybody with simple mechanical skills. it is always much cheaper. it contains 3 parts. 1 the desiccant cartage which is what takes the moisture out. 2 the purge system that takes the water droplets that collect on the bottom and spits them out every time the control system (line from governor ) is activated. this occurs every time the compressor reaches 120 psi and the governor unloader port becomes active. this is why air leaks must be controlled as if not, the purge will not work and the drier will fill with water. (and freeze in winter) and lastly the regenerative system which is why they can last for years. it simply when it is purging it will use some of the dried air in the large shell around the desiccant filter to go backwards out of the filter and deposit the water in the bottom to be purged. the ad9 also has a thermostat and heater element in the bottom to help it purge in the cold. to test them you must put them in a freezer and then before it gets warm check for conductivity as it warms up you should see the conductivity end to a open circuit. parts are easily available and usually have good instructions. just be sure to mark the bottom 2 case bolts where the lower mount goes

[mmoore6856]

the heater / thermostat part can be tested while unattached to the base so it will be easier than putting the whole drier in the freezer ps send the wife out while you do this

[mmoore6856]

one last note there should be about 6 to 8 feet of heat resistant supply (copper works best) air line on the supply side to start cooling the air as it is hot after being compressed. the air dries better when the air is cooled

[Booyah45828]

Agreed to the rebuild vs replace. The components to rebuild/refresh are available for cheap, no need to spend 500 on a new one. Dryers really aren't that complicated.

The spot that is taped looks to be before the fitting, and is likely a leak/crack from the copper vibrating and work hardening. They make teflon lined braided stainless hoses that can replace the copper and lasts much longer.

If the taping is before the connector, a new drier won't fix it, you'll have to replace that copper tubing.

[Bus'n it]

The tape job and loose connection are where the copper line joins the fitting. It is also greasy at the joint. I am sure thats one of the air leak down locations. I guess for that pipe I will have to go to the bus depot for parts. The other end of the copper also has a piece of foam and electrical tape at that fitting where the black air line from the compressor goes in. The whole shebang is zip tied like everything else under there. In my storage build project, I will re secure all that crap using the frame hangers and adel clamps. Again, crazy as to the maintenance thats done on these. Regarding the air dryer, My intent of replacement wasn't the loose fitting but rather not having to go back in there again. I've been crawling on the dirt on my back the last week or so. My legs are all cut and scraped. yes, I wear shorts and drag my butt on cardboard, but weld splatter, grinding sparks, AZ caliche ground and general bumping in difficult places takes its toll! I am amazed I am still at it!

[mmoore6856]

also if your compressor is worn out and blowing oil into the system you are wasting your time on the air drier. need to fix that first

[mmoore6856]

Originally Posted by Booyah45828

Agreed to the rebuild vs replace. The components to rebuild/refresh are available for cheap, no need to spend 500 on a new one. Dryers really aren't that complicated.

The spot that is taped looks to be before the fitting, and is likely a leak/crack from the copper vibrating and work hardening. They make teflon lined braided stainless hoses that can replace the copper and lasts much longer.

If the taping is before the connector, a new drier won't fix it, you'll have to replace that copper tubing.

yea i really like those braided stainless/Teflon lines but they are spendy

[Bus'n it]

The oily residue is very slight and only at the taped up connection. Compressor pumps up quickly. No residue elsewhere

[mmoore6856]

Originally Posted by Bus'n it

The oily residue is very slight and only at the taped up connection. Compressor pumps up quickly. No residue elsewhere

replace the entire fitting using one that has dot stamped on it as that means its certified for air brake use. use new copper line with no hard kinks

[Bus'n it]

Originally Posted by mmoore6856

replace the entire fitting using one that has dot stamped on it as that means its certified for air brake use. use new copper line with no hard kinks

Would a braided line that transitions to the nylon line work? I asked the dealer about the copper line and they do not have any part numbers since the bus is old. I haven't taken it apart yet. I need to be able to move it for the next few weeks. Today I power washed everything under there. Should have done so before welding in the storage framework! Ah, well, its Arizona and it dries fast!

[s2mikon]

100 r5 hose is DOT rated for air brakes. You can get reusable ends and make your own hose.

[mmoore6856]

It must be able to withstand high heat from the compressor

[mmoore6856]

maybe the ss/braided at a junkyard might be cheaper than copper with the prices lately