Air brake canister 1993 917 AF

Hello!

I recently developed a leak in my right rear service brake on my 93 917 AF and I"m trying to get help sourcing the part or a repair kit. I've reached out to several USA based companies that work with older Mercedes trucks and one company in Romania.

The failed unit is made by Bosch. The prior owner replaced the left side some years ago. The Mercedes part number he used for the left side is: A0204209218. This is what the tag has on the right rear brake canister: Bosch 002 420 43 24 , 7176. A friend of mine that works at Mobile Fleet was able to pull up some after market part numbers using the tag on the brake chamber.
Wabco part number 4253600000 or a Euclid E33.16.001,
repair kit part, Euclid WSK.49.5. A few calls to Mercedes Benz in San Francisco were dead ends, they stated they did not have access to European market parts/trucks.

So I'm trying to source a replacement (OEM preferred) and a repair kit to have on hand for the road.

Any help would be appreciated!

Thanks!
 
MB USA is absolutely useless even with vehicles that were sold new in NA, i.e. U500. Hopefully they’re reading this.
Contact parts, Neil Webster, at Merex in Gaggenau, Germany.
 
It really helps to have the correct part number. Do you have an online way to determine that?
There’s 2 sites that are like mini EPCs. MB in its great (lack of) wisdom seems to have made EPC itself totally unavailable to private individuals, at least in North America. If anyone reading this knows of a way to subscribe to EPC for NA private individuals, please contact me through PM.
 

VerMonsterRV

Gotta Be Nuts
I just completed a brake refresh including new brake canisters. I asked my very helpful friend in Germany (Stefan who is a retired Mercedes Mechanic) and he said they never rebuilt the rear canisters when he was working. The parking brake spring is too dangerous to mess with (the fronts they did). Also the inside of the air chamber in these canisters were a mess with rust, so glad I didn't even try to rebuild.

So I ordered a couple of the after market ones from DT Spares off of eBay Spring brake cylinder DT Spare Parts 4.67635 Spring brake cylinder left M22 | eBay and Spring brake cylinder DT Spare Parts 4.67636 Spring brake cylinder right M22 | eBay (they are right/left). They bolted right up except we needed to rotate the canisters to get the air fittings to line up with the originals. I also replaced the wedge units (I replaced all 4 and since the 2 fronts seemed ok, I kept them as spares, the rears were a mess) and brake linings. When I took things apart I was very glad to replace everything as it was a mess. I also replaced the front canister diaphragms, they seemed to work ok but once I opened them up the rubber was hard and cracked in a few places.

One thing I would recommend is to get some of the brass air elbows with your order. They are 2 piece and cheap from Europe. I didn't do this and we really worked hard to save one of the fittings as it was frozen in place. Luckily (so we could get back on the road) we were able to chisel the canister housing apart to free it. Plus there are small O-rings inside of these fittings which age. They are used in a lot of places in our trucks, and are probably one of the reasons we lose air overnight. I need to order up a bunch of these. For us A0049905371, A0009970934 and A6739970145.

IMG-20221103-WA0006.jpg
 
Thank you so much for the links! I’ll order one today. Do you sharing where you got the brass elbows? Sounds like to good idea to secure those too.

If I recall, you were looking at options awhile back for a break refresh. What did you end up going up with?
My plan was to go through all 4 corners after winter and refresh/rebuild everything wirh OEM parts.


Sent from my iPhone using Tapatalk
 
Last edited:

DiploStrat

Expedition Leader
As noted, even US MB dealers cannot access the truck parts list.

The gentleman who sold me the wheels for my 917AF recommends these folks. I have no personal experience, but hope to take my truck to them next year.

Link:https://aignertrucks.com/

Best wishes.
 
Last edited:

VerMonsterRV

Gotta Be Nuts
One thing to remember about aftermarket parts vs OEM. Some parts are NLA from Mercedes and the only source is aftermarket.
Thank you so much for the links! I’ll order one today. Do you sharing where you got the brass elbows? Sounds like to good idea to secure those too.

If I recall, you were looking at options awhile back for a break refresh. What did you end up going up with?
My plan was to go through all 4 corners after winter and refresh/rebuild everything wirh OEM parts.


Sent from my iPhone using Tapatalk
I ended up rebuilding all the brakes, but with mainly aftermarket parts. Even with aftermarket parts and shipping it ended up around $2600. Also, I think that some of the parts are not even available from Mercedes anymore. In the rear I used the DT combination canisters, PE wedge units, SBP drums and Textar brake linings. The wedge units did lack a couple of holes to fix them in place while you bolted things together. Not a huge deal, but would have been slightly easier. It also would make just replacing the canisters down the road easier. Now if I need to replace the canisters I would need to remove the brake drums first. With any luck I will never need to replace them again. For the front I used PE wedge units, PE rubber diaphragms (for the canisters), SBP drums and new linings. The Textar linings are not metallic like old Mercedes ones (not sure what they are doing now).

I can say this, our brakes are now better than we have ever had since we have owned this truck. I am having to relearn the required amount of brake pedal force needed to slow us down. I feel much better now knowing more about how these brakes should work and what condition they are in. I do know that I will add a yearly check where I remove all the rock shields, check the gap (.7mm), and have Heather use the service and parking brake while I watch from underneath.

For the air elbows I haven't gotten them yet. Shipping can be a pain (not to mention costly), so I am trying to work up a small parts list before I make an order.
 
Are you talking about Voss air fittings. My generation vehicle (2005) uses Voss 232 fittings but there’s a previous generation. I got a comprehensive spares kit in an organizer image.jpgfrom the UK that I’ll probably never need.
 

VerMonsterRV

Gotta Be Nuts
Are you talking about Voss air fittings. My generation vehicle (2005) uses Voss 232 fittings but there’s a previous generation. I got a comprehensive spares kit in an organizer View attachment 754092from the UK that I’ll probably never need.
Yup, those are the same idea as the ones we have. I need to assemble a few of these as spares. Other than corrosion the o-rings get hard with age.
 

VerMonsterRV

Gotta Be Nuts
This is the elbow that is cracked and leaking.

View attachment 754446
I am not 100% sure but I think that is a vent line (if you look at the DT aftermarket canister picture you will see a small rubber bung in the same position). If I envision it right, the compressed air enters/leaves the left side (in this picture) of the clamp ring. On right side of the clamp is the space for the rubber diaphragm to expand and push a plunger towards the wedge unit. So you would hear air escape when the brakes are first pushed but then stops, even if you keep the brakes engaged. This was the area that we had a lot of rust (about a 1/4 cup poured out). Inside the narrow part to the right is the shaft from the plunger which mates to a cup on the end of the shaft from the wedge unit. That shaft on the wedge unit has a spring on it to push the canister plunger back into the non-braking position.

My guess is if all else internal is ok, then this canister would be ok as long as water hasn't damaged anything inside. In our case the wedge unit spring was destroyed with rust everywhere. One other thing to look for is the pivot pin for the brake shoes. When the shoes are installed you put grease into the bearing surface. Other than taking the shoes off I don't see a way to re-grease these. Taking things apart I could feel a bit of resistance for the shoe to return to the non-braking position (actually one was stuck in the open position). Although it was a bit of a pain to do this project I am really glad I went through each corner refreshing things. Pretty sure our brakes haven't worked this good in very long time.

On a brake side note. In Europe I am hearing it is common to be able to test your braking force as part of the yearly inspection. Anyone know if this is even possible in North America?
 
I am not 100% sure but I think that is a vent line (if you look at the DT aftermarket canister picture you will see a small rubber bung in the same position). If I envision it right, the compressed air enters/leaves the left side (in this picture) of the clamp ring. On right side of the clamp is the space for the rubber diaphragm to expand and push a plunger towards the wedge unit. So you would hear air escape when the brakes are first pushed but then stops, even if you keep the brakes engaged.
Mine continues to leak as the brakes are engaged. That makes me think the diaphragm is failing. Please correct me if I'm wrong. I'm new to these systems.
 

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