haoz129

Issue description:
This winter is pretty cold. The front heater couldn't deliver enough hot air. Rear is normal blowing nice hot air.
Please note, my car has separate rear climate control.

Diagnose:
Engine cooling is working well and coolant temperature is always around 180f/80c when car is hot.
Rear heater is normal indicating the whole AC system is ok.
There is air blowing in the front but air temperature is low. Seems the coolant can't reach the heater.
Front dual-valve control the coolant flow to front heater.
Further checking REST(Residual Engine Heat) function:
- When engine is hot turn the key off and remove;
- Hit the front REST: front vent blows air but not hot. Stand in front of the car can not hear pump spinning.
- Hit the rear REST: rear vent blows hot air. Can hear pump spinning around right front wheel area.
Above symptoms indicate the front circulation pump (auxiliary water pump) is not working. The circulation pump is part of the front dual-valve which controls and optimizes the coolant supply to front heater in all engine working condition. Bad pump distinctive symptoms:
- No hot air when car idle vs has hot air when engine rpm high as main water pump push coolant to compensate the weak circulation pump;
- Front no hot air in REST mode vs rear REST work as front and rear each has their own pump.

Solution:
Regular fix is to replace the front dual-valve (A220 830 00 84) which include the circulation pump. Part is around $250.
In my case I just need the pump (A220 835 00 64), part is around $150. The pump is attached in the dual-valve and it is the same part for front and rear dual-valve.
If buy used pump, one from rear valve of hot area car is better which will be used less and has plenty of service life left.
I ended up buying a used dual-valve from a florida car and use the pump only. See picture 1 for front dual-valve; picture 2 for valve anatomy, circulation pump is on right top of the picture.

Repair: Replace circulation pump which is on top of the front dual-valve. No need to remove the valve body.
The front dual-valve located in the engine bay and in front of the fire wall just beside the brake booster.
1, Open hood to upright position and remove both wipers;
2, Remove the plastic weather trim by removing 4 plastic rivets. Now the wiper mechanism is exposed, see picture 3;
3, Remove the wiper mechanism by removing 4 13mm nuts. Now the Dual-Valve is exposed, see picture 4;
4, Undo the electric connector from the circulation pump;
5, Remove the pump, impeller housing and impeller by unscrew 4 screws holding the pump on the valve body, see picture 5; see picture 6 for the pump disassembled;
6, Use multimeter to test old pump resistance. Got 50k ohm which is considered as open circuit, should be 6 ohm;
7, Install the new pump including the impeller, impeller housing and don't forget the o-ring.
8, Install other parts.

Result:
Test the REST function in the front. Heater supplies hot air when engine is off.
Heard front circulation pump runs when REST selected.
Front has enough hot air even when drive slow or idle.

Cost: CAD
- $60 for the used dual-valve, I only used the circulation pump though.
- 2 hours spent.

wallyp

Excellent job on diagnosis, on repair, and on documentation!

haoz129

Thanks, my pleasure you like it. Hope it helps people.
I keep improving my documentation base on members' feedback.

If you want please rate my thread as I will be happy to see how many people like it.

All the best.

Howard

haoz129

Coolant should be replaced every 150kmiles/240kkm or 15 years which comes earlier.
This S600 has 85kmiles/136kkm and 10 years, taking the following factors into consideration, I decide to replace the coolant:
- This winter temperature hit -22f/-30c last month;
- Refresh the anti corrosion will help to protect the engine.

Fluid:
- MB antifreeze x 2: BQ 1 03 0002 (MB 325.0)
- Distilled water: 8 liters

Procedure:
- Mix coolant 1:1 with distilled water. The mixed coolant won't freeze until -30f/-34c;
- Drive front on ramp, apply parking and block rear wheels;
- Remove middle and front under engine panelings;
- Locate radiator drain screw on driver side and drain the coolant, see picture 1, the screw is the red one which can be turned by hand, so no tools needed;
- After draining re-tighten the screw. It's a pleasure to use the screw to drain or stop, nice design and very convenient;
- M275 holds 12.21 liters and I Got more than 10 liters out from the radiator. Good enough so I didn't drain the engine block.
- Old fluid is clear but has some white deposit;
- To refill coolant, I disconnect the windshield washer heater and use the two hoses to help;
- Apply vacuum from one washer heater hose and use the other one to suck coolant in;
- After there is no vacuum effect anymore, re-connect the washer heater hoses;
- Pour more coolant into the coolant expansion tank;
- Idel the car till the engine reach working temperature, monitor coolant temperature and level. Add coolant if needed;
- Rev engine to higher rpm to push air out. Check coolant level, add coolant if needed;
- Stop engine and check for any coolant leakage. Then put back the under engine panelings;
- Drive and monitor engine temperature. Check coolant level, add coolant if needed.

Cost:
- Coolant: $45 for two bottles;
- Distilled water: $2 for two 4L bottles;
- 1 hour spent.

haoz129

Got a bad feeling the other day. The lady behind the dashboard suddenly started to whisper so I can't hear the navigation.
I need went to few places not quite familiar and had to ask my passenger shut up. But I still could hardly get the instructions.

I thought the navigation was going then I check the Comand Manual found there are two ways to adjust Navigation volume:
- Sound/Voice setting for Navigation;
- When the lady start to talk turn your volume up;

I never figure out the first way but the turn volume works perfectly when the lady is giving instructions.
That is a brilliant design, works like magic, the same volume control, controls navigation volume when the woman talks, controls CD/Radio when CD/Radio plays. I wish it could control my wife's volume as well, .

Only drawback is I am not that intelligent to understand how it works in the first place.
Now I know why the navigation volume was suddenly lower, it was because I tried to adjust CD/Radio volume when navigation was in effect.

Once again, nerver ordinary a mercedes.

kraut56

the comand system stores a separate, dedicated volume level for each selectable audio function; e.g. telephone, cd, nav etc.; you only affect the volume level on the "active" audio if you adjust.

haoz129

Thanks Ulrich.

Learn new stuff everyday.

Howard

kraut56

I forgot: It also stores dedicated audio adjustments, so you have to go thru each function and adjust the audio, balance and Bose "space" equalization for each one individually (makes sense, because radio or CD can sound quite different if not adjusted. On my car there is also Cassette player with many adjustment choices for Dolby I, II or III, and once adjusted properly these old cassettes sound amazing - Bose sound!). Once set, only the volume level can be changed or altered "accidentally".

Nice to hear from you, Howard. Weather is so crappy here I rarely take my beauty out of the garage; took her out to go to the Bon Jovi concert - result: as a black car, she's all dirty now; too cold to wash.

haoz129

Same here Ulrich. Snow never end.
One week -30c, the other week +10c,

Mine has snow tires and is my daily driver for business. She performs very well in snow and ice. I use the Volvo for the weekend shopping.

Silver is not that bad, lots of icicles around bumpers. But spring is near.

BenzBoy12

This is an amazing thread, keep up the good work. Incredibly useful and informative.

haoz129

Thanks BenzBoy, glad you like it.

It's my pleasure to share my experience and benefit forum members.

Howard

haoz129

Put new brake pads in the front when switching to all season tires.
At the same time inspected the car and found four ABC hoses are wet.
When those high pressure hoses are old the rubber deteriorate and the hoses start weeping. Most of the time it is from the fitting connection.
At the very beginning the weepage is small and doesn't affect driving. But if it is ignored finally the hose will give up and burst which will cause serious problems.

Many forum members had ABC hose burst and stranded on the road. This could be dangerous on the highway and, in some cases, lead to pump replacement.

According to above facts I use the weepage as a warning and replace hoses in question.

There are 10 high pressure lines/hoses in ABC:
1) Pulsation damper: directly connected to tandem pump through banjo and has two rubber hose sections;
2,3) Pressure lines from pump to PSV(Pressure Supply Valve), 1st part and 2nd part:
4) Pressure lines from PSV to split point:
5,6) 2 Pressure lines from split point go to front and rear valve blocks;
7,8,9,10) 4 Pressure lines from valve blocks to 4 struts;
In my case, 1,3,4,7 are wet and will be replaced.

According to Nick and Drewk88's experience I didn't buy OEM lines. As mentioned some lines are just too hard to remove. Instead I cut the rubber section including the fitting and had a hydraulic shop make the rubber hose with proper fitting. Then I connect the new hose to the original metal line. This way I could always easily replace those rubber sections in the future when they have signs of going bad. Please see picture 1 for new and old hose compare, and picture2 for all the new hoses.

I followed Drewk88's instruction for replacing the pulsation damper it worked well. In addition I raise the engine 1 to 2 inches which made putting in the damper and aligning the banjo bolt easier. As Drewk88 mentioned I access the banjo bolt from the front of the pump by using a fine teeth wrench.
Before I could work on the banjo bolt I did remove the following:
- fan shroud;
- v belt;
- ABC pump pulley;
- ABC/Steering reservoir;
Please see picture 3 for the old pulsation damper and picture 4 for the new one which is already in place.

Other hoses are easier than the damper, please see picture 5 for the PSV and picture 6 for the 2 high pressure lines attached to the PSV.

I asked the shop to use high quality hoses and fittings. 4800 psi system were chosen (include hose, compression fitting, ferrule, locking nut) which is significant higher than the ABC working pressure (3000 psi). The damper was made pretty well. I was worried about putting the damper back will be hard as in such a tiny space even a little bit size variation will make the damper impossible to fit. Any way the result is good. Other hoses are good as well.
Make sure to use insulation material and foil to wrap the rubber hoses which are near the exhaust. This reduce the heat to the hose and prevent oil getting to the exhaust in case it weeps again.

After connecting all hoses back, performed the routine to restart the tandem pump:
- Pour enough Pentosin in both ABC and Steering reservoirs;
- Pre-pressurize ABC reservoir to make sure pump get oil;
- Start the engine and hit ABC raise vehicle switch, wait for 10 second, stop the car and add ABC fluid;
- Start the car again and check all new lines for leaking;
- Drive the car then check oil level and lines for leaking;
So far so good.

Cost:
$500 for making the lines/hoses;
$50 for new o-rings and other parts;

More than 20 hours work not include making the hoses.

Welwynnick

Nice work Howard - that's the way to stay on top of ABC!

Quick question though - when you raised the engine, did you disconnect any electrical or fluid connections?

When I changed my damper hose I didn't do that, and it certainly was a difficult job. Keeping everything clean was tricky - I covered the hose ends with small plastic bags until they were in situ.

And just to clarify something for others - the old flexible sections are removed by cutting the metal pipe (not the flexible pipe), then fitting a new hose using compression joints onto the metal pipe sections.

Best regards, Nick

Edit: Thinking about this a little more, maybe it would possible to replace flexible hoses in situ. Just drain the fluid, and cut through the metal pipe as close as possible to the flexible section, then fit the replacement hose with the compression fittings. You'd have to carefully work out how long the new pipes should be, and take great care to keep the pipes clean, but it might work. My preference would be to remove the pipe in question, but this approach might reduce the car's time off the road.

haoz129

Thanks Nick,

The ABC is maintainable and under control if we do inspection and replace question hose when there is a sign of deteriorate. Definitely don't wait for the hoses to burst.

To answer your question: Other than remove two bolts under the engine mount I didn't disconnect any harness or pipe. I didn't, but you could disconnect the big black engine oil line which is just beside the pump banjo bolt, this will make the work easier.
The whole job is hard, you must know, even to align the banjo and two stack lines is so difficult. I am proud to say, I have been there.

Yes, my pressure lines were cut from the metal pipe as close as possible to the fitting. By doing this way I didn't have to remove the whole line. Some lines are too hard to remove.

Yes, to make sure hose clean is very important.
Make exact size hose is tricky too, I measured every old hose cut and give the shop the length so they could make the new hoses correct size. But the #3 hose is still 4mm longer which make it difficult to fit.

Regards.

Howard

wallyp

Howard,

Good work on the hose replacement.

"But I the #3 hose is still 4mm longer which make it difficult to fit." I would think that a little long would be pretty easy to fix - a 4mm cut with the tubing cutter. 4mm too short would have been tougher...

haoz129

Thanks Wallyp,

This is a very good question.

Please see the attached picture1 for line#3 (see the U shape steel pipe). The pipe goes backward along the engine to the front of the transmission on the passenger side, then turns to driver side, then makes a U turn back towards the Pressure Supply Valve on the passenger side.

After I cut the rubber section with the fitting, there is not too much metal pipe left I can use to fit the new hose's compression fitting. Pipe near bend can not be used to fit the compression as it is less likely to be round, hence may cause leaking. To be safe, there should be at least 1 inch away from the bend to fit the compression. See picture2 for the finish result.

So I don't want to cut more pipe as it will be impossible to add pipe in case the fitting couldn't be sealed due to too close to the bend.
By the way, there won't be enough room to use the tubing cutter. And the cutter will cut more pipe.

All the best.

Howard

wallyp

I can see why simply cutting a bit more off the end is not an option...

I also realize that you have solved the problem, and don't need any more suggestions, but-
Would it have helped to cut the other side of the U-bend, and insert a compression fitting, thus moving the hose connection location a little further away?

(Some of us old pharts just enjoy coming up with odd solutions to other folks' problems!)

haoz129

I hear ya, and I live the same way.

Yes, we could always cut and add connections to adjust the line/hose. But in such a high pressure system one more connection means one more point to leak/fail. Since I was lazy and so caucious so I didn't extend the line that way.

Now it fits ok, if it was not able to fit I'd like to make a shorter hose to solve the issue.

Have a great weekend!

Howard

300SDLguy

Fantastic job documenting the repairs on your S600. I only wish the mechanics the work on my S600 and CL600 at my Mercedes dealership were half as competent as you. I also wish I was as skilled and fearless as you in doing the repairs. Before the warranties runout on mine they will be sold, the CL600 is in the shop more than its out. I was just telling someone that I can write an article on even the most subtle of differences between the 2012 and 2013 C300's <grin>, since I have driven them more as loaners than my CL600 for the past year.

haoz129

Thanks 300SDLguy for your compliments.

Yes, it is not easy to find a good mechanic who you can trust to work on 600.
The warranty does help to offset the heavy expense.

And because of that I'd like to share my experience about this car so people are armed before dealing with the dealer.

All the best.

Howard

Welwynnick

IThis is what I've been doing with my S600. While I was upgrading the IC system, I had the front end apart, which allowed easy access to the pipe between the front valve assy and the RHS front ABC strut. I knew it had been seeping for a few months, and wanted to change the pipe before it failed (and we were about to go on holiday). This is what it looked like from underneath:



I raised the car, drained the fluid and removed the pipe - a few minutes' work for the valve end, and a few HOUR'S work for the "quick release" connector. I got my usual hydraulics contractor to make a new 3/8" two-wire hose with 10mm compression fittings:



They did it while I waited, and it cost £41. I scraped the paint off and thoroughly cleaned the metal pipes, then cut them with a plumber's pipe cutter, and fitted the new hose to the clean ends:



I ran some Pentosin CHF-11S through the pipe, and part-filled it before fitting. Access is awkward to fit the hose to the valve assy, so its easier when the headlight, the horn and the headlight washer are removed.



Here's the hose in front of the sub-frame. I skipped the solid pipe section there and protected the hose with a section of heater hose (I had a lot lying around...) and that fitted the existing bracket quite neatly.



Getting all the jacks and stands from underneath the car is tricky when the suspension doesn't support itself, but eventually I started the engine and raised the suspension up and down several times, keeping the reservoir fully topped up. It didn't leak a drop. A couple of days later I finished putting the charge cooler together and took the family on holiday. All that happened was I got a slight leak from a headlight washer pipe (another "quick-fit" connector ......).

That's how I look after ABC. This was a similar job to fixing the damper hose, but much easier this time due to better access, and simply because I'd done it before. Apart from the seized quick release connection, it was quite straightforward.

Nick

haoz129

Thanks Nick for another great experiment!

haoz129

This post is compiled base on many forum members' experience and contribution under this topic: Welwynnick, Drewk88, Eric242340...
The purpose is to help ABC owner to increase the ABC reliability and reduce the owning cost. You could find the ABC is never problematic if you follow the maintenance suggestions.
As usual, all the suggestions are base on my experiment and knowledge, hence not offical, please use them with your own judgement.

There are many occasions that ABC failed and cost the owner a lot to fix. Even worse, some of the problems happen again and again.
After reviewed and researched some cases it come to a conclusion that most of the ABC issues are preventable if we do regular maintenance.

That said, to keep ABC in a good shape and keep ABC cost reasonable, you have to do regular maintenance.
Why, we do regular maintenance on engine, transmission, transfer case, differential, etc... Why not ABC ?
E.g. if you leave the fluid in transmission as 'sealed for life', you trany won't last. ABC won't either.
If you can DIY, that's good. If not, insist your mechanic or your dealer to do the ABC regular maintenance for you.

Ok, stuff you need to take care:
1, Visual check ABC components, lines/hoses and fluid level during every A/B maintenance. Fix leaking or other issue promptly.
2, Regular fluid and filter replace: ABC is a hydraulic system which contain 4 liters of Petosin chf 11S.
- Please replace the fluid/filter on a regular basis, let's say every 30kMiles/50kKm.
- The ABC fluid has its life span just like engine oil, transmission fluid, etc...
- As the fluid degraded/contaminated the internal parts in ABC (pump, valve body, strut...) will rust, accumulate deposit or get clogged
- Water contamination is a common but serious problem in Hydraulic industry. It is a critical and regular process to maintain hydraulic fluid in those heavy equipment.
- A simple way is to syphon/empty the ABC reservior then fill with new fluid and replace the filter. Within a week or two adjust height often for better circulation. Then syphon/empty and refill the reservior 2nd time. This way most of the fluid is refreshed.
- There will be some old fluid left in the hoses and struts, but it is good enough if you don't have any sympton.
- If you have lowered corner issue, you may need a rodeo to flush the system, again rodeo/flush is not necessary for regular fluid replacement.
- Be sure to change the ABC filter now if you still have the original ABC filter. The original filter is 10 micros and the new filter is 3 micros.
- Here I documented my fluid/filter replace, not simple version, but have some information could be referenced:
https://mbworld.org/forums/5158952-post74.html
3, ABC lines/hoses replace. There are rubber hydraulic hoses in the ABC system. Hoses need to be replace when it is weeping oil, otherwise it will exploded finally.
- Hydraulic hoses are made from rubber which will deteriorate for sure. Especially true for ABC which is constantly running under heat and pressure.
- There is no rubber hose build for life. But the hoses will not explode without sympton either. There is plenty of time to identify the weeping hose before it gives up.
- Check and replace hydraulic hoses in the Hyrdaulic industry is a common practice. Leave the hoses unattended will lead to hose rupture and disaster.
- Check or have your mechanic to inspect every ABC lines/hoses during the A/B maintenance. Replace the line/hose which is wet or weeping.
- For DIYer we found a practical and cheaper way to replace hydraulic lines/hoses. Follow hydraulic industry regular process, we made our own hoses, which is cheaper. And we modify the line/hose and use standard hydrualic hose compression fitting to make the hose replace much easier, more like a plumber. Please see the process documented:
https://mbworld.org/forums/5659409-post162.html

Above is the regular maintenance you need to follow. Below are more information to help you handle ABC related issues.
4, ABC action list. For each ABC owner please familiar yourself with the list and have it handy. It will help you diagnose and react correctly in case you have ABC issue:
https://mbworld.org/forums/5376771-post100.html
5, For lowered corner issue: Most of the time it is the Valve Block internal leaking, replace o-ring is the first and cheap way to fix:
https://mbworld.org/forums/5184137-post81.html

All in all, ABC is a great system combined with sensors, computer and hydraulic system which provide a superb ride quality. There is no fatal design and build issue as many guessed in the system and the ABC is continued to be used as the core of the MBC(Magic Body Control).
I also understand there are unpleasant experience related to ABC. It is caused by one lost link in the chain: regular maintenance. There is no clear maintenance schedule for ABC and the dealer is lack of knowledge of maintaining hydraulic system too, as Hydraulic is another industry.
There are so many different kind of hydraulic systems in heavy equipment/vehicles. They are reliable, dependable and reasonable in owning cost because they are well maintained. ABC should be one of them.

Again, don't neglact the ABC. It is our, owners', resposibility making sure regular/preventitive maintenance is done. Not just replace fluid when it acts up, at that time it is already too late. Check hydraulic lines/hoses regularly and replace any in question. In the Hydraulic industry everyone does this, why not for ABC. Do not wait for the hose to explode, there is risk when you are driving although the shutoff valve will protect the system and keep the strut height. As a concequence, the system is open and you lost fluid which lead to pump failure. $200 hose triger a $2000 pump failure. When the pump failed it may pump metal into your system messing up everything... Do not let this happen.

All in all, I hope the information gathered here could bring attention to you that regular maintenance is a must for ABC, plus to clarify any confusion you want to know about this unique suspension system.

Thanks.

Howard

RoCL

Fabulous thread!!!! Definitely educated me about DIY ABC.

Do you know if the v12 TT in your s600 is the same as a CL600 2003 -2006?

Also, all of yout ABC work applies to 2003-2006 benzs that have ABC?

Thanks!

RoCL

What issues have you had with your cl600?