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 Working on air valves
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Art Love

Australia
6237 Posts

Posted - 03/27/2010 :  04:43:16  Show Profile  Reply with Quote
Francis raised this and Chris and he decided that a new thread would be best. So I thought I would start one. The right front valve on the 300SE coupe had a significant leak which was dropping the right front corner very quickly. I had bought a set of second hand valves not long back. So I connected the compressor up the the right front unit using my specially made hose and shoved it in a bucket of water and it didn't leak. So I decided to swap valves. I did it today.

It is not an easy job on the car. We put the front of the car up on stands and removed the right front wheel. In the RHD cars, the steering box is in the road in front and above the valve. It would be easier in a LHD car. All sorts of bits and pieces are in the way and it is hard to get more then a fraction of a turn on a spanner on any of the air lines or the bolts. I used the two spanner technique which I described in the air bellows thread. I did not take any pictures today, but shall in the future.

The basic principles that I followed were as follows. Release the control rod at the ball joint. Release all the air lines with the unit attached to the axle. Use the pipe spanner to "crack" them loose, the an open ended 12mm spanner. You just can't get the pipe spanner on and off. I started with the one to the bellows in the middle on the bottom, then I did the ones at each end then the high level one at the top last. It is helpful to release the airlines where they are held to the subframe by the clamp. When all were fully released, and this involved a lot of time turning each one just a little at a time because of the very limited room. Then I released the two bolts that hold the unit to the subframe and removed the unit.

For instillation, I attached the inner line first. It has the least movement. It is absolutely essential to start every air line thread by hand. Cross threading is a disaster. To achieve this, I believe it is necessary to have the unit loose from the subframe so that you can move it in one hand while you try to engage the thread with the other. This more or less gets harder and harder the more lines are attached. I recall have dreadful trouble with the left front valve. Everything has to line up perfectly for the thread to start. Leave each one half done up till all of them are engaged. It is not a fun job. I then tightened up all the airlines and then installed the two mounting bolts. I found that I had to attach the inner of the two bolts first. With the outer one in, the inner one would not engage the thread. The other problem that I had that I had not forseen was that I left the mounting bolts out while I installed the air lines and then found that the I had dreadful trouble getting them in because the RHD steering box was in the way!

I finally got it all done, took the car down off the stands after putting the right from wheel back on and reattaching the control rod. And, guess what, the vavle leaked like a sieve from the center shaft, having shown no sign of a leak in the test!!! So the right front of the car went straight down again. Serves me right for not having the valve rebuilt before I put it on. So this is a job I shall be doing again in the near future and I'll take some pictures.

Art

Chris Johnson

USA
3751 Posts

Posted - 03/27/2010 :  06:33:34  Show Profile  Reply with Quote
Just out of curiousity, which port on the valve did you apply the compressed air for the test? I would like to think that this would be a valid test.

Chris Johnson
If you aren't constantly impressed with your car, then it needs fixing.
100.012-12-000790
100.012-12-000867
www.300SE.org
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FEMA

USA
1392 Posts

Posted - 03/27/2010 :  12:26:35  Show Profile  Reply with Quote
Art, thanks for starting this thread; I'd like to address the approach to diagnosis as I feel intimated thus far by the air suspension system

I know Chris that you are intimate with this and at this point my plan is to look at a past service record in which my dealer tech dignosed which valves were leaking and need replacement. I'm also thinking perhaps I just replace all with new and be done rather than try to diagnose in the event I screw it up.

All that said it would be great to uunderstand how we should approach the problem to determine which valves leak and which don't because it's not like I have extra money to burn on unnecessary parts

This may already be outlined in a previuos thread and if so, I don't mean to add repeated information here but will go look over that thread and we can dialogue here and there as appropriate.

Francis E. Abate
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Chris Johnson

USA
3751 Posts

Posted - 03/27/2010 :  13:43:58  Show Profile  Reply with Quote
I'll make a generalization, but it is accurate 95% of the time. If the car sinks after the engine is shut off, one or more height control valves is leaking.

These are no longer available new, so they must be rebuilt. I did recently pickup two "new" rear valves and two (one each side) "new" front valves. I haven't tested them yet, nor do I intent to because even so called new valves are still going to have to be rebuilt in order to be reliable after this period of time.

The most common leak in a late style valve (all 600s and 300SELs) is from the seal at the internal operating lever. This air usually leaves the valve assembly at the hinge pin for the external lever. Spraying some soapy solution (409, etc.) at this area on a valve that is pressurized will show bubbles if there is a leak. It is a good idea to spray the entire valve and connections with the soapy solution to reveal other possible external leaks. Other typical leaks are from between the line screw adaptors and the body of the valve and from between the line adaptors and the line nuts. Both of these external leaks are readily fixed with new rubber O-rings (of the correct type). Other than leaks around these fittings the valve is not repairable by us mere mortals, so they must be sent off for rebuilding.

I'll post some more later this evening.

Chris Johnson
If you aren't constantly impressed with your car, then it needs fixing.
100.012-12-000790
100.012-12-000867
www.300SE.org
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FEMA

USA
1392 Posts

Posted - 03/27/2010 :  17:25:11  Show Profile  Reply with Quote
Chris;

I'm very disappointed these are no longer available new as I believed they were, but last I checked was a couple years ago now. The problem is I've heard the rebuilts don't have a good track record so if there are any sources better than others hopefully someone will post those here.

I'll look forward to your further explanation on leaks but suffice to say now my front end drops over time or when the car is not run often.

Francis E. Abate
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Ron B

Australia
11633 Posts

Posted - 03/27/2010 :  17:33:05  Show Profile  Visit Ron B's Homepage  Reply with Quote
The rebuilt units are as good as the new ones in general. There are three main people world wide doing it. Neil Dubey being the first I believe to do it. if you want to spend a great deal of cash,the guy in Germany will fix them as new . In OZ we have Mr Black in Melbourne .
In all cases the rebuilt units will give as god a service as new ones and significantly cheaper.

quote:
12-14-2004, 11:49 PM #8
Tom Hanson
MBCA Member

What the heck, try to stuff a MB 6.9 liter V8 in it. What a machine that would be..
__________________
Tom Hanson
Orange County Section
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Art Love

Australia
6237 Posts

Posted - 03/28/2010 :  03:32:55  Show Profile  Reply with Quote
Chris,
It is a valid test. I'm with you on that. I was brain dead when I did it at the end of a long day at about 8pm and applied the air line to the E port instead of the B port. My bank balance is looking seriously empty at the moment and I was being too stingy to send a set of valves down to Alex Black in Melbourne for rebuilding. I'm just annoyed with myself because, as you know, changing one of these valves is not an easy job. The valve on the car was leaking air from the two screw holes that hold the high level pipe brass end fitting. I've not seen that before. There was no leak around the centre pivot bearing of the control lever or from the retaining pin hole. As far as I was concerned, it still meant that the seal on the centre toggle (operating lever) was leaking, letting pressure from the lower half of the valve into the non pressurized upper part. The one I put on leaks like a sieve from the control shaft pivot bearing - the usual place.

I'm getting too old to spend 3-4 hours on my back under one of these cars. I get quite nauseous for reasons I don't understand. Now I've brought the car home to put it on stands in my garage to get it out of Justin's shed because he needs the room. We have to take the radiator out to pull the oil driven fan coupling off and put new seals into it to stop the chronic oil leak from it as well as taking both front valves off to send down to Alex. Justin will send the valves from his 6.3 as well as a job lot. Today I went to start it from where I parked it on the road out the front of my house last night at the end of a long day only to have the starter motor totally die after as initial start. The damn thing is totally dead, so I've now got another problem to deal with even before I can get it into the garage.

Francis,
Tom Hanson confirmed that new valves were NLA when I asked him last year. New valves were still available when I rebuilt #1702 in the mid 1990's. I paid a fortune for them. They have lasted no longer than the rebuilt ones. Rubber seals are rubber seals. The big advantage as far as I am concerned is that Alex Black will be starting with valves that no one but Bosch have screwed around with. He told me that his biggest problem was dealing with trouble done by other people. I have had exactly the same experience when I was rebuilding my own valves. I had valves with Araldite, Sikaflex and all sorts of stuff in them - Loctite as well I suspect. Some of the valves I had would not unscrew - the brass end fittings sheared off before the valves moved. Most people mucking around with these things haven't got a clue as to how they work. I'll post the original Bosch cutaway diagrams here which include all the Bosch part numbers for the individual parts including the seals. I was still able to get the seals in the 1990's. I haven't tried since and still have some of them. I'm not posting the diagram for the part numbers so much but mainly to show you and others who are interested what is inside these units. It is appropriate for this thread.
Art
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Art Love

Australia
6237 Posts

Posted - 03/28/2010 :  03:41:21  Show Profile  Reply with Quote
Here is the diagram. The seal that leaks the most is 17 in the diagram.





It's getting a bit late and I don't want to start a long discussion on how this thing works at the moment. Chris may wish to go through it and I can add my tuppence worth if he does. Otherwise, have a good look at it and I'll go through it tomorrow. I'll also take some photos of some of the internal bits I have on the bench so you can compare them to the diagram.
Art

Edited by - Art Love on 03/28/2010 03:43:40
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FEMA

USA
1392 Posts

Posted - 03/28/2010 :  10:57:44  Show Profile  Reply with Quote
I'll look forward to that Art.

Ron, I had heard even from Neil directly that the rebuilt valves are like a 50/50 chance of working or not so that is my concern - please correct me if I am wrong as it is not my intent to suggest poor work by anyone. It may just be that these things are tough to deal with.

That said does your guy in Australia or the guy in Germany give me the best chance of only doing this once? If you guys have their contact info please post it here and I will contact them directly and research price, availability, risk, etc.

Francis E. Abate
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jeen

Netherlands
10 Posts

Posted - 03/28/2010 :  12:18:01  Show Profile  Reply with Quote
Hi guys

The site below is giving a good explination of the system

www.luftfederung.de

Jeen
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Art Love

Australia
6237 Posts

Posted - 03/28/2010 :  18:04:20  Show Profile  Reply with Quote
Chris Johnson will have the first part of his articles on the air suspension in the next Lode Star. That will supplement this thread, or perhaps it is the other way around.
Art

P.S. I also was incorrect last night in saying that seal #17 in that diagram is the main cause of the leaks. It is a seal that is not separately identified on that diagram. Seal 17 surrounds a brass housing that looks like a black rectangle in the diagram in the middle of which is a ball with a vertical shaft through it. The seal that leaks is between the ball and the brass housing.

Edited by - Art Love on 03/28/2010 18:10:03
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Chris Johnson

USA
3751 Posts

Posted - 03/28/2010 :  19:20:44  Show Profile  Reply with Quote
And it is that seal that cannot be replaced without damaging its housing, so a new housing is required. Just removing and re-installing this housing can damage the aluminum valve body if not done perfectly. This is one of the three principal reasons why repair of these valves must be left to an expert.

Art, I had to bail out on an important trip before I got time to finalize that article. I didn't think that it would make it into the next issue. Thanks to you and Anthony for picking up the ball and running with it.

Chris Johnson
If you aren't constantly impressed with your car, then it needs fixing.
100.012-12-000790
100.012-12-000867
www.300SE.org
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Art Love

Australia
6237 Posts

Posted - 03/30/2010 :  04:25:51  Show Profile  Reply with Quote
I promised to post some pictures of the bits and pieces.

Here is what you are used to. This is a left front valve, 2 A connections, 2 E connections, 1 B connection and 2 high level connections. That is 7 air lines and 2 bolts that you have to line up. I have spent over an hour or two or 4 connecting one of these valves up on a 6.3.




If you undo the 2 screws that hold the high level unit to the top, and remove the unit it looks like this.




Then if you look into the cylindrical hole where it came from, it looks like this after you remove a teflon shuttle (and spring as I recall). I'll post a few pictures of the shuttle later.




The first thing is a teflon roller which is mounted on the shaft of the control rod. If you look at the diagram I posted, you will see that roller as a large striped disc. If you look carefully, you will note that there is a V notch cut into the circumference of the disc. It is at 7 o'clock in the diagram. Beyond the roller is the end of a steel shaft with a vertical steel pin located in a hole in the end of it. Beyond the shaft in the dark is a heavy spring unit.

Now, here is the teflon shuttle looked at from three perspectives.




upside down.




right way up.




and end on. The other end is circular with the bottom third cut away. You will notice on the upside down view, there is a V shaped ridge at one end. Well that ridge engages the notch in the roller on the control shaft when the roller is in just the right position to do so. When the ridge is engaged in the notch, it drives the shuttle one way or the other as the control shaft is pulled or pushed one way or the other. The pin you saw sticking out of the high level unit fits down that small hole in the end of the shuttle. At the other end, it fits over that steel shaft with the vertical steel pin in it.

If you undo the brass air line connections A and E at the opposite ends of the body of the unit, you are looking at the outer ends of the outlet and inlet valves respectively. Here is one of these valves.




I can't remember whether this is an inlet or an outlet valve. But if you push on the pin that sticks out of the inner end of the valve, you can quickly tell, because one has a soft spring holding it out and one has a very hard spring pushing it out. So, one is much easier to "open" than the other. To be quite honest, I've forgotten which is which, but I'm sure Chris will know. For the sake of what I am saying now, it doesn't matter. With the inlet and outlet valves out, you can look right through the cylindrical bore in the lower half of the valve unit.




What you can see, sticking down in the same bore that the airline connection B to the bellows screws into is the other end of the steel pin that you could see looking into the bore at the top of the valve unit. NOW I AM NOT SAYING THAT ANY OF YOU SHOULD DO ANY OF THIS DISASSEMBLY. This is for explanation only. I am sure that Chris and others will have their say, but there can be all sorts of problems doing this. The positions of the inlet and outlet valves in the bore of the unit are critical for example. When I have more time, I'll mention a few of the other problems I have encountered doing this.

This is what that vertical toggle pin unit looks like.




Here I am pushing the pin one way and the other to show you how it works. It is the seal INSIDE the brass casing, between the ball in the middle of the steel pin and the brass casing that causes 90% of the airleaks in these units. It does all the work.








You can see seal 17 in the diagram that seals the outside of the brass casing to the vertical central bore in the valve unit. The second circumferential cut out which is at the top of the brass housing (I'm holding it upside down in the two pictures) is to locate the unit in the bore using the steel pin that goes all the way through the casing. Here it is beautifully undisturbed in this unit. It is right in the middle of the picture.




Here is what you need to drive it out to release the center toggle unit.





Don't ask how many of these fine punches I have broken trying to drive out these pins. They have a very slight taper and I could never remember which way they drove out. Electrolysis often siezes them in as well. I got this one out.





So, leaving it at this stage, because I have to go out, when the suspension drives the control rod up or down, it rotates that roller which moves the shuttle one way or the other and the shuttle pushes the top end of the toggle pin in and the heavy spring pushes it out and at the opposite (lower) end of the toggle pin, the ball on the end either pushes the inlet valve open or the outlet valve open accordingly. In the central position both are closed. I'll do some more tomorrow when I have time.
Art

Edited by - Art Love on 03/30/2010 07:57:39
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paul-NL

Netherlands
4288 Posts

Posted - 03/30/2010 :  04:38:18  Show Profile  Reply with Quote
Watch out !!!



Those "bullet"valves are DIFFERENT for the inlet- and outletside and don't switch them.

What is the difference ??
The spring from the = as I remember well = outletvalve is MUCH STRONGER then the spring from the inletvalve.
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Chris Johnson

USA
3751 Posts

Posted - 03/30/2010 :  10:50:53  Show Profile  Reply with Quote
Indeed, the one with the strong spring is the outlet valve. The inlet valve has a check valve in it to prevent the reverse flow of air, and this allows a very light spring to be used to hold the flow valve on its seat. Because of the check valve, it does not matter if the flow valve is blown off its seat when the air bag compresses and the pressure at the "B" connection goes above the pressure behind the flow valve.

The outlet valve, on the other hand, does not (and can not) have a check valve in it, so the flow valve itself has to be able to withstand normal pressures as well as these transient over-pressure situations and not allow any air to escape, and it is that big spring that ensures this. The valve must open only when it is physically opened by the lever.

Chris Johnson
If you aren't constantly impressed with your car, then it needs fixing.
100.012-12-000790
100.012-12-000867
www.300SE.org

Edited by - Chris Johnson on 03/30/2010 17:23:34
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Ron B

Australia
11633 Posts

Posted - 03/30/2010 :  17:11:03  Show Profile  Visit Ron B's Homepage  Reply with Quote
The guy in Germmany makes his own toggle valves and I think he sells them to those who want to repair their own valves. Once the amount of effort required to make such a part to high degree of precision is recognized then it will be understood why the overhual cost is so high.

quote:
12-14-2004, 11:49 PM #8
Tom Hanson
MBCA Member

What the heck, try to stuff a MB 6.9 liter V8 in it. What a machine that would be..
__________________
Tom Hanson
Orange County Section
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