News: THE 600AIRSUSPENSION SHOP is open now! The 600AirSuspensionShop.com is a great asset for the Mercedes community making parts available and helping to maintain these beautiful cars. The Store is a complementary option for people and shops inclined to work on their cars.
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Mercedes Air Suspension Solutions

What we do

We are offering professional renovation for core parts of the Mercedes air suspension system from 1963 to the early 70s (Mercedes 600 from 1963 to1981), mainly level control valves, valve unit, anti-freeze device and pressure regulator for the 600 , W112 and W109. Other products are under development*.

Legendary Air Suspension

You are probably familiar with the Mercedes models W 109, W 112 or even the W 100 from this time.

These models were designed with a ‘legendary‘ air suspension system, legendary in a positive way - the ride in such a car is superior compared to a steel spring system- but also legendary for the complications the owner might experience and finally legendary for its price.

The air suspension system technically was potentially the best suspension system on the market at the time it was designed. It was for sure the best-engineered system of its time. However also this well designed system needs rebuilding. Oh yes, you will notice when it is time. If your car drops within one week or so the time has come.

Maintenance and Repair

No doubt, the air suspension requires a higher degree of maintenance. And most possibly your system will work perfectly fine if it was brought back to spec. This means the failing components need to be repaired/ rebuilt and the system maintained according Mercedes specs.

The bad news is: The repair can be overwhelming and rebuilding the valves units by a qualified specialist does not come cheap. Engaged and experienced DIY people can repair some of the air suspension components but the renovation of the core components like the 3 level control valves, main valve, anti-freeze device and pressure regulator should be in the hands of the specialist. Too much knowledge, experience, specialized tools and precise instruments, testing equipment and parts are needed for rebuilding.

From my personal experience I can tell that you will enjoy every bit of a ride with a proper working Mercedes air suspension.

Our Products

We work with passion and our products are based on integrity and honesty. We share our knowledge with the community and we like collaborating. We use the best technology and craftsmanship available. Our CNC parts are ‘Made in Germany’ and we use high quality seal rings and materials. All repaired parts and units run through extensive testing. We are giving a 2-year warranty for air tightness and function within specification for units and parts. You are requested to sending your units for rebuilding before we start and we will rebuild the units within ca. 2-4 weeks of turn-around or upon request. Prices are based on the assumption that provided cores are repairable which typically is the case. We will keep our clients informed about the process and communicate if there is a problem.

We take a $200 core charge for LCV-VNC, Anti- Freeze Device and $250 for the Valve Unit , $500 for the Pressure Regulator in case we deliver up front.

What is done during Renovation?

Level control valve renovation:
disassembly, all parts cleaned, unit body cleaned (ultrasonic) and sealed , steel parts zinc plated/ chromate, seals exchanged, E, A and Stk replaced by new CNC machined and sealed parts, proper lubrication, adjustments according MB specification, pressure testing, new seals for air line fittings. VNB units receive new rubber/steel bearings.

Valve unit renovation:
disassembly, all parts cleaned, unit body cleaned ( ultrasonic) and sealed, steel parts will be zinc plated/ chromate, inner valves inspected, cleaned, damaged parts exchanged, proper lubrication, adjustments according MB spec., pressure testing, new seals for air line fittings. Pressure switch will be tested but is excluded from repair. In case the pressure switch is defective it can be replaced by a replacement switch for $100.

Anti-freeze device renovation:
disassembly, all parts cleaned, unit body cleaned ( ultrasonic), steel parts will be zinc plated/ chromate, inner valves inspected, cleaned, exchanged, adjustments according MB spec., pressure testing, lubrication, new seals. Exchange of paper air filter element included.

Pressure regulator (600 only) renovation:
disassembly, all parts cleaned, unit body cleaned (ultrasonic) and sealed, steel parts will be zinc plated/ chromate, inner valves inspected, cleaned, damaged parts exchanged, proper lubrication, adjustments according MB spec., intensive pressure testing, new seals for air line fittings.

Drain Valve (bottom of air tank) renovation:
disassembly , all parts cleaned, steel parts plated with chromate, NBR seal exchanged, pressure tested.

Check Valve (side of tank) renovation:
disassembly, all parts cleaned, steel parts plated with chromate, machined new valve, new NBR seal, pressure tested.

Manipulated Units: Very rarely I am finding ‘manipulated’ units. These are units that were previously "repaired" by non- professionals leading to partial destruction of inner parts. These are very difficult and time consuming to repair due to broken or missing parts. These parts need to be machined and the effort is obvious. Please understand that working on manipulated units will possibly cost some extra effort and in case I will communicate and discuss with the client. Thanks for your understanding.




Please do not hesitate and ask questions.

Parts under development

Pressure Test Adapter: This tool is for easy testing and monitoring air pressure in the support group (air tank) and filling the system with shop air.
This tool is for the professional Mercedes shop but also for Mercedes enthusiast.
This tool screws into the pressure switch port of the valve unit and allows for easy and safe pressure testing / monitoring with a standard AC gauge and 1/4" flare hose. With a long hose system pressure can be monitored during driving.

Articles

Related Videos

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Mercedes Air Suspension Repair Services

Pricing

Prices for rebuilding Mercedes Air Suspension W109 1965-72, W112 8/65-67, W100 1963-84 and W112-8/65
Units to be sent for rebuilding

Level Control Valve for W112, W109 and W100, complete rebuilding.
LF/VNC 3/1 [0-500-003-004],
LF/VNC 3/2 [0-500-003-005],
LF/VNC 4/3 [0-500-003-006].
These are the 3 later style units for front- right, front- left and rear.		 $580 per unit
Level Control Valve for W112 , complete rebuilding.
LF/VNB 3B2 / 3A2, Front Left
LF/VNB 1B1/ 1A1, Front Right
LF/VNB 2B1 / 2A1, Rear
These are the 3 earlier style units, before 1965		 $880 per unit
Main Valve for W112, W109 and W100, complete rebuilding, pressure switch excluded.
0-501-001-004,
0-501-001-005		 $550 per unit
Anti-freeze device, rebuilding inner valves and all rubber seals, paper air filter change included.
000-431-14-15		 $480 per unit
600 Pressure Regulator (W100), complete rebuilding and pressure adjustments.
0-481-040-001,
0-481-040-002		 $1080 per unit
Drain Valve (bottom of air tank), complete renovation
LF/ VE [0-500-400-001, -002]		 $120 per unit
Main Check Valve (engine side of air tank, complete renovation
LF/VB (0- 500- 100- 001, -002, -003)		 $120 per unit
Air Filter Unit (part of anti freeze device) complete
renovation, paper air filter change included		 $120 per unit
Air Compressor
additional parts/machining bronze bearing
new piston pin 		$900 per unit
$120
$30

Customer is covering shipping, duties and customs clearing (for shipping outside the US)

Core charges for up front services:
$200 for LCV-VNC and Anti-Freeze Device core
$250 for the Valve Unit core
$500 for the Pressure Regulator core
Core charge will be refunded after receipt of core

Contact

Martin Werminghausen
Engineer
Professional Experience: Maybach/MTU/Mercedes in Germany
Registered Architect
Location:
141 South Great Rd.
Lincoln, MA 01773, USA

Email: 600AirSuspension@gmail.com



Reviews

Review by

Simon Haynes


We are one of the largest restoration companies based in the UK specialising in Mercedes-Benz from the 1960’s 1970’s and 1980’s.

Our Classic Department focuses on offering clients the opportunity to restore, repair and maintain their Mercedes-Benz to the very highest standards, as these vehicles become older and in most cases more valuable, year on year it becomes increasingly challenging to achieve and provide quality and reliability.

I am pleased that these demands are always met when dealing with Martin from 600airsuspension.com who we have used for many years now.

Martin is very knowledgeable, skilled and always comprehensively communicates extremely well during whatever works he is carrying out for us.

I would not hesitate to recommend his services with complete confidence.


Simon @ John Haynes Auto Technics


Review by

Herve Labesse


In october 2017 I found a very nice mercedes w109 near San Francisco California . The car was running fairly well at first, but it started showing very rapidly that it was in need of several overdue maintenances. One of them was a leaking air suspension system.The car would stay up for a couple days and start lowering itself on the front driver side and then pretty soon it would end up resting on the tires.. After some research on the internet i was able to locate 600airsuspension.com There were so much good recommendations for Martin’s work and his full understanding of the system was so clearly stated on his web site, that it was an obvious and educated choice to have him rebuilt my complete system. The car i purchased has had the air suspension gone through in the past couple years, but the work was not documented and most likely not done properly. I pulled the valves, anti freeze unit , check valves and main valves and shipped them beginning of march 2018. within a couple weeks they were rebuilt and when i installed them back myself..the system performed flawlessly. I had my air tank tinned inside out by Oregon re tinners..so the system would be taken care for many years to come.
Needless to say that the valves were as new when they came back with the proper plastic pins to be able to perform the hight adjustments. So, wether you are in the continental united states or in Europe and you own a w109 car..don’t waste your time and money trying to do the work yourself or entrusting it to your local mercedes mechanic.. send it to Martin ..you will only have to do the work once..and will have plenty of free time left ..to enjoy driving your car..


Review by

Atle Naavik, Norway


Hi Martin

Thanks a lot for your help with renovating the valves and components in my 6,3. I got frustrated with my 6,3 that would sit down in just a matter of hours. Since I had more issues with the suspension I decided to go all the way to do a complete rebuild of the suspension. You did a magnificent job with the valves. They works perfect and they look beautiful.
I really appreciate all the help you gave me and how quickly you returned the valves. I also got a chance to learn how the air system works, which has been very helpful.
Doing business with you has been a pleasure.
I will highly recommend you for any air suspension work on early Mercedes cars.

Review by

Frank Knieriem, USA


Hello Martin,
I would like to thank you for the fantastic service I received from you,
dealing with my air suspension issues on my 300SEL 6.3. I have to say that
as a German, I work like working with German engineers.
My first conversation with you, I already knew finally someone who knows what
is going on. I have a 1971 300SEL 6.3 which I purchased in Tokyo. The car has
really low miles but also has been sitting still for 20 years.
Of course the air-suspension was shut. The car went up but at the same speed
dropped again when we turned off the engine. The airbags looked old, so we replaced
the 4 airbags first. No change. We cleaned the valves and tank, or so we thought.
After installing everything again the car decided to only go up in the front.
I found you through a video of another Mercedes shop on youtube. When I saw your
video, I knew already that you would be the only person to fix my problem with the 6.3
Sure enough; you did exactly what you promised. Fix my system. After you sent all the
parts back now 7 weeks ago, we cleaned the lines as you suggested and put everything
back together. Martin, except for a small mishap when we confused two lines, which you figured out for us it was a smooth process. You actually took the time to figure out
what we did wrong, while you were in Germany. The car is now up for 6 weeks. Any valve repair from now on, there will be nobody else for me. As a matter of fact you are working now on my Maserati Merak headlight valve. Who knew that
it's the same
switch as the one on a Mercedes 600.
Thank you for everything you did for me. Have a great 2017.
Best regards

Review by

Jay Manek, UK
W100 Grosser 600 No. 505

Posted - 05/05/2014
http://www.m-100.cc/forum/topic.asp?TOPIC_ID=8083&SearchTerms=air,suspension
I think Martin is well known here.
I have written this email to him today and I think it should be shared.
Dear Martin at 600 Air Suspension,
I would like to thank you sincerely for the absolutely outstanding service I received from you whilst dealing with my Air Suspension Troubles on my 600.
From the first email I was entirely convinced of your knowledge and attention to detail on this matter.
You helped me diagnose my problem remotely and then offered a solution at a price that I was happy with.
I am so afraid of dealing with sharks in the classic car restoration world, I know of many who have lost tens of thousands $ by entrusting their cars to the wrong people.
I was sent detailed step by step pictures and commentary of my new air valves being restored which you completed in a reasonable time frame.
The exchange service meant I didn't have to disassemble my car whilst you were preparing new valves for me. Also I did not have risk my valves getting lost with a courier!
I feel this level of customer service is lost nowadays in the world of fast and cheap service.
You have given me and my historic vehicle the level of expertise that would make even the original designers proud.
My car is now riding as it should and no longer sinks to the ground over night. As trivial as it may sound, It makes me so proud to walk into my garage and see my car still raised up as it should rather than slouched down looking sad.
You have not only gained a customer for life but a friend and I hope to meet you some day in Boston.
Now when are you going to start repairing the hydraulic parts!?
All the best.

Review by

Ruud, Netherlands W100:

Posted - 09/09/2014
http://www.m-100.cc/forum/topic.asp?TOPIC_ID=7895&whichpage=3
After reading most of the posts here, and watching Mr. Werminghausen on youtube, I thought it would be safe to send my air suspension valves to Mr Werminghausen. The old ones were not bad, but when the drain valve of my airtank was leaking (took me some time to figure that out), the front of my car would sink - most probably a leaking E-valve. I must say, Mr.Werminghausen sent me a set perfectly overhauled air valves. They look like new, but more importantly, there is no leak any more, and consequently no sinking. Also - at first I thought it was a matter of misperception - the steering and cornering of the car feels better. The difference is not big of course, but the car feels a bit more agile, and even a little bit more comfortable. Finally, communication was great, even though he lives in the US and I in Europe. Sending and receiving the parts was simple and on schedule. I know that there are more addresses for this, and probably good ones, but from my own experience I can highly recommend Mr Werminghausen. (And I didn't get a discount for writing this :-)


Review by

John Heller, Atlanta GA


The front air valves on my 1970 300SEL were leaking down completely in less than 24 hours. These valves had been rebuilt within the past 5 years but yet they were leaking down again. I sent my air valves to Martin for him to diagnose and rebuild. He quickly diagnosed the problem as an internal leak with the E-valve. Once diagnosed he entirely rebuilt both valves. He kept me informed via e-mail through the entire process of diagnosing and rebuilding. The turn around time was excellent and I had my air valves back within a week of him receiving them. The rebuilt valves were returned in beautiful condition and correctly adjusted to the proper Bosch/MB specifications. I would highly recommend Martin in rebuilding the Bosch/MB air valves.


Review by

Scott Melnick, CA

Hi Martin
Greetings from California!
Just wanted to send along a BIG THANK YOU for the help on my last 2 suspension problems. Both the 600 SWB and the 6.3.
Your expertise and quick repair of the Air-Valves really helped.
In the future, you'll be my "go-to" guy for air suspension problems and help.
Thanks again

Best Regards,
Scott Melnick
Auto Engineering/Classic Mercedes-Benz


Review by

Kari Voutilainen, Helsinki, Finland

Hi Martin

I have a MB 300 SEL 4,5 that suffered from a leaking air suspension. The problem kept getting worse all the time and in the end the car was on her belly overnight. We managed to point the leak to the left front valve levelling bar hindge. Luckily I found Mr Werminghausen and his 600 Airsuspension on Youtube and contacted him via email. Since my car was already scheduled at the workshop Mr Werminghausen generously proposed to send me one of his already reconditioned valves and refund me as soon as he received my old leaking unit.

We followed the instructions found online at 600airsuspension.com and the fix was a perfect success. My car is in the Finnish national museum-car-registry, so it was imperative to use original parts to solve the problem. Nothing could be more original than the reconditioned original part. I am very happy with the workmanship and service of Mr Werminghausen.

All other old valves seem to be air tight so far, but when the eventual leaks appear I know who to call. I’m also considering a complete overhaul of the entire system in advance, but I’m having hard time convincing my engineer to change something that is not broken - yet.


Kari Voutilainen
Helsinki, Finland


MB300 SEL 4,5 1972



Mercedes 600 Komfort Hydraulik Solutions

The ‘Komfort Hydraulik’ System Serviced

We are offering professional renovation for core parts of the Mercedes 600 (Mercedes 600 from 1963 to1981) comfort hydraulic or KH system (German: Komfort Hydraulik) with Bosch or Barmag pump, Teves (ATE) Piston Accumulator and Connectors, Switches and Valves as well as Pistons. Basically all parts of the system that may leak can be serviced, rebuilt and pressure tested.

A very Unique System

You might think the Mercedes 600 hydraulics is a description of an aircraft system… but it is not. This is a support system in a car and probably the most unique, expensive and sophisticated system offered in a car. 

The 600 models were designed with a hydraulic system that surpassed the luxury and elegance of other cars by far. The system is very reliable but with age the rubber and pressure connections, switch valves and piston seals start to leak which causes a lot of grieve for the 600 owners.

The comfort hydraulic system is probably the most unique feature of the legendary Mercedes 600 but also one of most feared ones. If any of the parts fail it will lead to problems that can be minor like a seat or a window moving slowly by itself or pump or accumulator failing which is leading to uncomfortable situation like potentially releasing the hydraulic door latches during driving. This will not lead to any great risk because the door will not open during driving but it might feel a little strange. The most common problems are oil leaks to the inside of the car, which is annoying and cannot be tolerated. There might be other internal leakage in a switch or piston, which results in a loss of pressure but no external leaks.

Maintenance and Repair

The Mercedes 600 hydraulic system failure requires attention and proper maintenance. The repair can be overwhelming and rebuilding the units by a qualified specialist does not come cheap. A hobbyist cannot do the repairs and Bosch did not foresee any DIY repair, not even the change of pressure port seals. Any repaired units must be pressure tested on a bench or tested on a test stand, like the pressure pumps.

Our Products

We work with compassion, integrity and honesty. We share our knowledge with the community and we like collaborating. We use the best technology and craftsmanship available. CNC parts are ‘Made in Germany’ and we use high quality custom seal rings and other materials like Teflon or Delrin for custom seals or valves bodies. Depending on the situation custom designs might be required. In some cases for instance Teflon seals can be designed and machined. All repaired parts and units run through extensive testing. We are giving a 2-year warranty for tightness and function within specification for units and parts. You are requested to sending your units for rebuilding before we start and we will rebuild the units within ca. 2-4 weeks of turn-around or upon request. Please ask for turn-around. Prices are based on the assumption that provided cores are repairable which is typically the case. We will keep our clients informed about the process and communicate. 

Bosch and Barmag pumps will be tested on a dynamic test stand to confirm functions and correct pressure settings (175 and 200 bar).

What is done during Renovation?

Bosch and Barmag Pumps:

Dis-assembly, all parts cleaned, unit body cleaned, surfaces and threads check and recut/corrected, steel parts zinc plated/ chromate, seals exchanged, new ball bearings, new bronze bearings if needed, adjustments according MB specification, static pressure testing for pressure check valve and over pressure valve, dynamic pressure on test stand for pressure build up and output pressure adjustment 175/200bar. New touch-up paint. Steel parts/ports plated/chromate. Barmag pumps often require machining of new bridge seal and suction check valve.

Teves Piston Accumulator:

Dis-assembly, all parts cleaned, unit body cleaned, steel parts will be zinc plated/ chromate, Piston replaced with new-machined part and modern accumulator seal, all seals exchanged, new high pressure Schrader valve. Nitrogen charge 100- 110 bar, pressure testing. Check valve dis-assembled, lapped and pressure tested. The diaphragm accumulator cannot be serviced.

Switches:

Dis-assembly, all parts cleaned, unit body cleaned and repaired, bores reamed, surfaces corrected, inner valves inspected, new CNC-machined rings and seals, adjustments according MB spec., pressure testing. Damaged levers exchanged.

Pistons:

There are a variety of pistons used and there are a couple of different size sizes. We try to take car of all of them. Most of the time the piston seals are fine but leaking pressure ports need to be rebuilt. However in case the piston seals are damaged we take care of this problem and most of the time the piston seal can be rebuilt with a custom design in Teflon/ NBR. Disassembly, all parts cleaned, unit body cleaned, damaged parts exchanged, intensive pressure testing, new seals and seal rings for pressure ports

Connectors and Shut-off Valve:

Dis-assembly, all parts cleaned, seal and seal rings exchanged, pressure tested.

Please do not hesitate and ask questions.

Prices for rebuilding Mercedes 600 comfort hydrailic units to be sent for rebuilding

Hydraulic Pump Bosch or Barmag, complete rebuilding $1,250
Piston accumulator ATE/Teves $1350
3- way connector $220
2- way connector $160
1- lever switch, level excluded $490
1- lever switch w/ throttle, lever excluded $520
2-lever switch . lever excluded, $650
3- lever switch, lever excluded $810
4- lever switch, lever excluded $960
Shut-off valve $250
Single acting ram, inner piston seals excluded $100
Double acting ram , inner piston seals excluded $180
Hydraulic Oil Filter Kit , replacement for original filter $40


Reviews


Review by

Ruud, Netherlands

It has been a long time, but I guess one shouldn't rush fixing the hydraulics of a 600.. But finally, finally my car holds pressure for a long time. And to be honest, not so much due to my skills, but for the most part due ot the interventions of Mr. Werminghausen. Some of you may remember this old thread, that started with problem that in approximately three or four days all hydraulic oil would flow back to the reservoir - including the oil from the accumulator. So every time I would take the car for a drive, it had to repressurize. For way too long I tried to find the element(s) with an internal leak ‘downstream’ as Mr. Werminghausen calls it. That is, behind the shut-off valve. But whatever I tried (the book describes some testing procedures), it never prevented the reservoir from being filled after a while. In the end I even tried to block the return hose completely - still the same problem! Then I remembered an almost forgotten suggestion that Mr. Werminghausen made months earlier. That is, to suspect the check-valves of the pump and the accumulator. So oil would not (only) flow back from the elements, but directly from the accumulator, using the supply hose. Finally it all made sense. But by that time the reprssurizing of the system started to take longer and started to act erratic. Just when I was wondering wether to remove both the pump and the accumulator (I always get nervous shipping parts), the accumulator seemed to have broken down completely, not being able to hold any pressure. Things got from bad to really worse. I discussed the repair of both the pump and the accumulator with Mr. Werminghausen. He strongly suggested to add a hydraulic gauge in the system, that would make it possible to closely monitor the system. Fortunately I had a spare flexible hydraulic line. After Mr. Werminghausen sent a gauge, I attached it to a spare connection of the shut-off valve. In the mean time I shipped both the pump (Bermag) and the accumulator to Mr. Werminghausen, who has developed a dedicated test bench for the pump. Both items were in desperate need for some attention, and the accumulator was even clogged with big chunks of dirt that may be deteriarated rubber. The hydraulic system really needs to be clean on order to keep working. Well, my parts were in a different condition - to say the least. Mr. Werminghausen completely overhauled both the pump and the accumulator, using new designed parts and even a new piston for the accumulator. The re-fitting of the pump and the accumulator is not too complicated. After starting the engine I immediately noticed the pressure build up by the gauge, that ended at exactly 200 bar. It has been quite a long adventure, but I finally feel that I am in control of the hydraulic system, and not the other way around. Much to the credit of Mr. Werminghausen to be honest, who suggested to add a permanent hydraulic gauge. I just feels great to really see how the sytem is behaving, in real time. No more guessing and assumptions. I do not own any shares in Mr. Werminghausens company :-) so I am at liberty to really recommend him for both the air suspension and you hydraulic parts. Besides the perfect job he is doing, he is always there to answer questions or share thoughts. Anyway, here is the setup of the guage: http://www.m-100.cc/forum/topic.asp?TOPIC_ID=5856&whichpage=3

Review by

Dan, Tacoma WA


1966 Mercedes Benz Grand 600 @36K miles

Current work: Hydraulics

My partner [Bradley] & I have been long time vintage car collectors/restorers . With the purchase of the Grand 600 we new something different was coming our way.
The 600, while in great original shape, had hydraulic issues that left us scratching our heads. Starting with online searches for specific repairs we soon realized there was little info or
service to be found. Eventually winding up on M100 forum, we followed a trail to 600Airsuspension and finally, Martin Werminghausen!

Martin has successfully rebuilt: Accumulator, hydraulic pump, door glass regulator pistons, auto door latch elements, window switch, a dozen or so junction blocks,control levers for sunroof/cowl vent and
most recently the master cylinder. Also, Martin has provided a hydraulic pressure gauge that adapts to the O.E.M. system, which helped in restoring the hydraulics of the Grand 600.
I'm happy to report that the hydraulic system achieves factory specs of over 3000 psi, and will maintain over 2000 psi for several weeks while garaged. All rebuilt working components continue to function smoothly,
and best of all NO HYDRAULIC OIL LEAKS!

Martin is genuinely concerned with his work and customer satisfaction; we would not hesitate to recommend him for repairs on this complex car.

Thank you Martin!


Mercedes W116 6.9 HPF Hydraulic Suspension Solutions

The ‘HPF’ system serviced

We are offering professional renovation for core parts of the Mercedes W116 6.9 HPF (German: Hydro-Pneumatische Federung) which include Bosch pump, pressure regulator, switch unit, axle valves, and struts. All parts or the system can be serviced and pressure tested.

HPF- The ‘New’ Air Suspension

Mercedes invented a variation of the air suspension involving hydraulics. The HPF is the successor of the original Air Suspension of the W112, W109 and the 600 cars if you wish.

The new system used smaller sized units for the pressure pump, regulator, lines etc. This was possible due to (10 times) higher-pressure levels of the hydraulics. Pressures are up to 200bar in the HPF system relative to 20 bar air pressure used for the air suspension system. The hydraulic system has also the advantage that hydraulic rubber seals last longer and the metal valve seats are no longer depending on rubber inside the axle valve. Another advantage was a seamless integration of the strut into the hydraulic system. This made the HPF system as good as the air suspension from its suspension qualities but also relatively tolerant and reliable.

However as the HPF comes to age the rubber is failing and metal seats can wear out leading to complaints, similar to the original air suspension. Nitrogen accumulators were used as air springs (working with 80-100 bar spring pressure) and with age the diaphragm of the accumulator starts leaking and fails. Accumulators should be tested every other year and changed if they lost pressure.

The hydraulic repairs are quite different from the former air suspension repairs and the system has a similar complexity. Oil however cannot escape unseen as does air. Oil leaks on the ground are witnesses of a leaking system begging for repair.

Maintenance and Repair

The 6.9 HPF hydraulic system failures require attention and proper maintenance. The repair can be overwhelming and rebuilding the units by a qualified specialist does not come cheap. A hobbyist cannot do the repairs and Bosch did not foresee any DIY repair except for testing pressures probably. Repaired units must be pressure tested or be tested in a test stand.

What we do

We work with compassion and our products are based on integrity and honesty. We share our knowledge with the community and we like collaborating. We use the best technology and craftsmanship available. CNC parts are ‘Made in Germany’ and we use high quality seal rings and materials like Teflon. Often custom designs are needed. In these case Teflon seals are designed and machined especially for this purpose. All repaired parts and units run through intensive testing. We are giving a 2-year warranty for tightness and function within specification for units and parts. You are requested to sending your units for rebuilding before we start and we will rebuild the units within ca. 2-4 weeks of turn-around or upon request. Please ask for turn-around. Prices are based on the assumption that provided cores are repairable which typically is the case. We will keep our clients informed about the process and communicate if there is a problem.

Renovation in Detail

Bosch Pump:

Dis-assembly, all parts cleaned, unit body cleaned, surfaces and threads check and recut/corrected, steel parts zinc plated/ chromate, seals exchanged, new ball bearing and shaft seal, assembly with special tools in order to guarantee tightness, static pressure testing and dynamic testing on test stand.

Diaphragm Accumulator:

This unit can be tested but cannot be serviced. Replacement required in case Mercedes specs are not met.

Regulator:

Dis-assembly, all parts cleaned, unit body cleaned and repaired, bores reamed, surfaces corrected, inner valves inspected and lapped, new valve bodies for check valve. Regulator adjustments according MB specs, pressure testing. Steel parts plated / chromate.

Switch Unit:

The Switch Unit is attached to the Regulator. Inner valves repaired. Valve seats lapped, new valve bodies and seals Cam disk tested. Unit pressure tested. Steel parts plated/ chromate.

Axle Valves:

Dis-assembly, all parts cleaned, Rubber and Teflon seals exchanged, Valves restored, new valve bodies, valve pressure tested. New original rubber boot installed.

Struts:

Dis-assembly, all parts cleaned, Rubber and custom Teflon seals exchanged. Per request new pressure hose and return tube installed. Steel parts plated/chromate.

Please do not hesitate and ask questions.

Prices Mercedes W116 6.9 HPF services

Prices for rebuilding Mercedes W116, 6.9 Units to be sent for rebuilding

HPF pump, Bosch $440
HPF pressure regulator $850
HPF switch unit (attached to pressure regulator) $350
HPF axle valve $650
HPF strut , ball joints excluded $850

Reviews

Review by

Jordan Hunn, USA

Before I contacted Martin, my 6.9’s suspension wasn’t quite right. Despite new struts and spheres, the front still sagged when I parked the car and the suspension pressure light came on occasionally. The front leveling valve had been rebuilt by another specialist, but my mechanic complained that it didn’t seem to be working correctly. I reached out to Martin, who tested all of the hydro suspension parts and rebuilt them beautifully to spec. My hydraulics are now perfect, and I understand just what people mean when they talk about a “magic carpet” ride. It’s smooth, controlled, and trouble-free.

There are other hydraulic rebuilders out there who claim to understand the 6.9 hydro suspension. I believe that Martin is the only rebuilder in America who actually does. You will not go wrong trusting your 6.9 hydraulic parts to him.



Review by

Peter Bloedt, USA, Mercedes-Benz 600 & Classics Specialist


Hello Martin,

Just wanted to express my sincere gratitude and appreciation for your excellent work on the 6.9 regulator valve. I wish you could have seen the smile on my client's face, when his beached whale, a 1977 6.9, raised its belly for the first time in about eleven years of storage! I'm so glad I was referred to you by the Classic Center, and look forward to many years of doing business with you.

Greetings from California,



Review by

Tom Merritt, USA

So, if you want your 6.9 hydro-pneumatic suspension to work properly there is really only one person to do it and that is Martin Werminghausen. I say that with zero reservation. You just could not put yourself in any better hands and that goes for 600 and 6.3 air suspensions as well. He is truly the epitome of a great German engineer and to think he is an international architect that solves car problems in his spare time for fun. Thanks, Martin!!