biker349

my 2004 cl600 front struts are bouncing ridiculously bad when driving at any speed. the mechanic put the car on the lift and was able to move both front tires up and down very easily. he showed me cracks at the top of the strut right under each top attaching point. he said that was the problem. i asked him about welwynnik's method of replacing the rubber bushing on the top of the strut and he said the problem was the crack. do you think replacing the rubber bushing would solve the problem? the crack is extremely small and is on the underside of the strut just under the mounting support on the car and is extremely small and the fitting appears to be plastic. the car is undriveable because it is vibrating, shaking so badly. the whole car shakes and the front end bounces around. i've been trying to find the post about this and haven't been successful. what size tool do you need to unscrew the top of the shock to remove the washer holding the rubber bushing and what is it called? he also did a rodeo and found the pump was at 180 bar, but during the rodeo would go down to 107-110 bar. he concluded that the accumulators needed to be replaced. he also bounced the car while running and all four corners bounced. he said i needed 2 accumulators. i know there are about 5 in our system. do you think the 2 will suffice. he wants $1400 to replace the two accumulators including labor and 4 quartz of fluid. what is your opinion? he didn't give me a price for the front struts yet. all this happened at the same time on thurs. while driving on the highway at 75 mph. thought the car was falling apart. funny that both struts happened at the same exact time. any help and advice is greatly appreciated. my abc fluid level is good, couldn't find any leaks, no red, or white abc warning lights on dash, no intermittent abc warning lights when going over bumps. no malfunctions message on dash. no fault codes on star, just the pressure deviation on rodeo. any help is greatly appreciated. don't know why i can't find the original post on this? i'm in the vero beach area of fl. if anyone is nearby, or knows a good mechanic who can help this would also be greatly appreciated.
the best, harv
p.s. thought my abc was good and well maintained. new pump, 3 micron filter, multiple hoses replaced. that was all under an after market warranty. i no longer have the warranty and if i can't control the cost of this repair i may consider to coilovers. any feedback on strutmasters, yellow speed, etc. this is my only car so time is of the essence.

ItalianJoe1

Bushings won't cause bouncing when driving, it almost sounds more like you have a tire coming apart but a mechanic would know to check for that, i hope.

The bushings or strut mounts would result in a clunk or unevenness over bumps and a wallowing feeling, but if the road is reasonably smooth the car should drive fine. It is possible that the accumulators are failed, as they do with age, but again the only usual symptom is more pressure drop during severe bumps, on my car I get a flash of red ABC warning when I hit a large dip at high speed, but the car rides/drives ok otherwise. I know I need to do the accumulators but they aren't that detrimental to the normal driving behavior in my experience.

There were no issues during the rodeo? That's surprising. I would think maybe you had a front valve block issue or a pump pressure issue if it was actually shaking, maybe the problem you're having is not ABC related.

biker349

thanks for your reply. the tires are new. when the car sits on the ground and you open the hood there is a space on both front struts under the rubber bushing that i was able to stuff over 1/4" of rubber gasket material under. the ride is a bit better, but it still vibrates pretty violently. the pump showed 180 bar and went down to 103-110 bar during the rodeo. that was what made the mechanic think the accumulators were bad as well as the car bouncing up and down on each corner when he forcefully pushed down and let go of each corner. it appears that the 2 accumulators are one problem, but the space between the rubber bushing and strut support housing on top of both struts gives me concern. i don't think that is normal. is it? what do you think of $1370 to change two accumulators including parts, labor and fluid and do you think the struts need replacing, or rubber material added to the top ala welwynnicks thread?
i really appreciate your time and effort. you are a great resource and very knowledgeable. the best, harv

Welwynnick

Lots and lots of issues here, difficult to know where to start.

First, you say bouncy. Is that a wallowing bounce, like the bouncing on the springs without dampers, or is it a shaking bounce?

Secondly, diagnosing faulty accumulators isn't as simple as running a rodeo test. That tells you whether the pump is good, amongst other things, but not really the accumulators. They are checked by observing the reservoir fluid level.

You mechanics observations are telling. If the strut bush is loose and detached, then that 's a clear and obvious fault. Going by my experience, its a fault that can fixed quite quickly and cheaply. Its one of the big, easy wins. I would say try that first, see if it fixes the problem. THEN try the complex, expensive solutions.

I described the procedure that I used successfully in the ABC thread in my signature - see post 15. I'll see if I can link it, but its tricky by phone.

Nick

Welwynnick

https://mbworld.org/forums/m275-v12-...ml#post6656267

Welwynnick

When I fixed my struts, I removed them completely, but there' no need. Just undo the strut top washer, which is easier when the weight is on the wheels - the more weight the better in fact.

You can add an additional rubber washer to the existing one, or you can cut the old washer out and a fit a thicker one.

Nick

biker349

thanks for the response. it's a shaking vibrating bounce. the whole car bounces and vibrates uncontrollably making the car undriveable even at 15 mph. the shaking goes throughout the car front to back and even effects the drive shaft causing a lot of shaking throughout the console. even the cover for the sun roof vibrates. you can actually see the front of the car bouncing uncontrollably while driving.it's almost like all four tires are out of balance x 100, but the tires are new and the rims good. it's very disconcerting that all symptoms happened together with no previous warning. i got the tool and tried undoing the strut top washers. i was unable to move them even with the use of a hammer tapping on the tool. any trick, or are they reverse threaded. i was able to put about 1/2" of rubber gasket material under the washer due to the gap. it slightly helped, but car is still undriveable. the mechanic did push down hard on all 4 corners and every corner bounced about 4 times when he released them. my thinking is the upper rubber bushing are bad and accumulators ruptured. when the car was in the air he could raise both front wheels with basically no effort. i assume this shows a problem with both struts, possibly the upper bushing, but he shined a light on the front struts from underneath while the car was in the air and showed me small cracks on the very top of both struts. after the rodeo he checked the fluid for bubbles and level of fluid. no bubbles and fluid level was full.
thank you for all your help and feed back. you are an unbelievable resource for the board and myself. any more input is greatly appreciated.
the best, harv

ItalianJoe1

Severe bouncing sounds like the system is locked out, not allowing the pump to pressurize the struts when the engine is running. The car should barely move when pushed down from the corner, as it's a heavy car and the suspension actively works to hold it in place. All 4 corners makes me think the system is in a fault mode and shut down, or unable to control the valve blocks. IF there was a fault the system probably wouldn't even allow you to run a rodeo though, although I haven't tried personally via SDS.

I'd almost like to see a video of the car bouncing, but from what you say I'm gonna guess there's something keeping the ABC system from controlling the struts properly. That seems totally impossible if it passes a rodeo though, as that process really taxes the system and is designed to make any faults show up.

biker349

thanks, i've seen my car in the rodeo mode before and also seen videos of other cars during rodeo. my car performed as before and exactly as the ones in the videos i've seen. this is very discouraging as all symptoms happened at the same time with no apparent warnng, or signs of trouble. also the car doesn't sag even after sitting for multiple days and star doesn't show any faults.
the best, harv

Welwynnick

It might not be an ABC fault. Bad strut bushes don't cause shaking all the time - only when going over sharp bumps.


Does it shake all the time? What us it that provokes the shaking? There are lots of tests to do before jumping to a conclusion

Have you checked the wheel nuts?

I would look at the prop shaft bolts and flex plates.


Nick

Dr Matt

I agree with ItalianJoe, it sounds like the ABC system is not controlling the suspension at all. Bad accumulators wouldn't cause that, nor would worn strut top bushings. Your mechanic would have no chance of bouncing the car hard enough for the top bus gas to have any effect, and if ABC is doing anything there is no way the car should rebound 4 times when pushed on by hand. I have no idea what is wrong, but I don't think your guy nailed it either.

biker349

spoke to the mechanic again today. he believes the 2 accumulators are ruptured and the system is not pressurizing properly thus causing the extreme bouncing and vibration at all speed even over extremely flat roads. he says this even though the system is at 180 bar and the drops to 105-110 bar during rodeo, and there are no bubbles, or overflow in the abc reservoir and the dipstick reads full. he said this should solve the problem. when asked about the front struts he said they may still cause a clunk, or squeak and might need to be replaced. i don't know if i go along with all this noting some of the results of inspection and pressure. also i think $1300 is pretty high to replace the 2 accumulators, add some fluid and repair. all input is greatly appreciated. i will keep you guys posted as thing go along.
thanks to all and keep your input coming. it's all super informative, uplifting and helps keep me sane and encouraged.

Welwynnick

Just got down from a mountain, relaxing in a pub, so got some time now.


There are lots of things that don't add up.


What is it that provokes the bouncing/shaking?


Is it the driveline? Is it the road? Is it speed?


What's the frequency of the bouncing?


There's probably more than one fault. It sounds like the strut tops are bad, but there's something else as well.


If you're seeing 180 bar, that probably means the pump is OK, and the accumulators are NOT stopping the system from pressurising. The accumulators just store the pressure for dynamic demands. They act in parallel with the pump, not in series. If the accumulators are good, the fluid level changes from high to low in a few seconds when you start the engine.


Maybe you do need new accumulators, it's not unusual, but it sounds like your tech is guessing. The key is in the CHANGE in reservoir fluid level.

Dr Matt

The accumulators are pretty easy to replace. The passenger side rear requires removal of the muffler on that side which is not too bad. The drivers side rear is super easy as it just requires removing the plastic cover to get to it, 4 10mm nuts. The passenger front is also really easy, just remove the plastic belly pan. The drivers frot requires removing the left front tire and pulling out the wheel well liner. No big deal either. I've replaced all of mine and you should be able to buy all 4 for around $1,000. $1300 sounds high for any two to me.

biker349

thanks for replies. well appreciated. nick the bouncing and vibrating are provoked by movement. it doesn't matter if the road is flat, or uneven and as far as speed the vibrating shaking starts at about 15 mph and is pretty consistent at all speeds above that. meaning increased speed doesn't make the problem worse. the problem is on all four corners and we checked the driveshaft and rubber attachments on both ends and all is good with no cracking. i tried putting the car in neutral while coasting at 25 miles an hour and no change in the symptoms. so it appears that the drive shaft has nothing to do with the shake, vibration. the tires and rims are good. the bouncing, shaking is constant like in mili second intervals. i do believe the strut tops are bad, but all this happened at the same exact time so i believe that there has got to be some common fault causing most of this, but star doesn't show any faults. the fluid level does change from high to low almost immediately upon starting the engine. a friend suggested that there must be internal solenoids that meter the amount of fluid going to the shocks and that the solenoids may be locking up, or malfunctioning. i don't know if our systems work this way. i'm at a loss and as you don't believe it's the accumulators. this is really a frustrating scenario, but i'm sure our group efforts can figure this out. do you think the suspension computer could be the problem, but as i said no fault codes using star. i assume it's some type of mechanical problem that won't store a fault code. this is one for the books.
again thanks to all. keep your thoughts coming and nick please enjoy your vacation and thanks for taking the time while on holiday.

Dr Matt

Man I wish we were close. I'd say lets swap ABC control modules. I really don't think it is an accumulator issue.

ItalianJoe1

The driveshaft still spins in neutral.

I would try to spin the car up to 20mph or so on a lift and see what shakes. If it's that bad it should be readily apparent.

biker349

thanks guys. will do drive shaft test. question, wouldn't a bad abc control module throw a fault code? i don't have a spare module and would have to buy one.

ItalianJoe1

Yeah I don't think it's ABC related at this point but usually yes it will set codes.

biker349

okay, a little light at the end of the tunnel. turns out both my rear tires with 3000 miles have internal belt separation causing a violent vibration in the rear and possibly the whole vehicle making it undriveable. further the bushings under the washer at the very top of both front struts in the engine compartment has about a 3/4" gap between the rubber bushing and the body strut attaching point. possible collapse of both front struts, or damage to underside of strut below the body strut support. supposedly we can't go any further until the rear tires are replaced. then the rest of the system can be properly evaluated both physically and electronically. so it appears at this point that i had at least 4 simultaneous, or very close time frame problems so far. both rear tires with belt separation and both front struts with unknown problem. i guess when it rains it pours. hopefully i can get this sorted in the next week and don't find anything else. all you help is greatly appreciated and may still be needed as things progress. you guys have helped me greatly with your input, caring, expertise and support. i sincerely want to thank you all. you are what make this community great and i wish i could meet you all personally and buy you dinner and a beer. as i said i will keep you updated as things progress. btw, when i had the new front tires installed at goodyear i asked them to look at the rear tires and they said they were like new.
the best to all.

Dr Matt

Tires can look great on one inspection and fly apart in a really short time. Hopefully that's all it is. I still don't see why your car was rebounding 4 times when pushed on by hand, unless it wasn't running.

biker349

the car was running so i could also have an accumulator problem. we'll see once i get the shaking taken care of. that would possibly make three problems, but the accumulators if bad may have been bad for a while even though i didn't see any signs of that problem in the past.
the best

biker349

btw. found this thread it confirms pretty much everything that you guys have been saying, but is a good long read. thought i'd share.http://mercedes-abc-drive-carefully....y-part-of.html
the best

awiner

Biker, the link Welwynnick posted was indeed the one I suggested searching on in regards to the rubber top mounts.

If BOTH your accumulators were ruptured and filled with ABC fluid, you would be getting ABC errors on the dash whenever going over any bump or dip. Possibly even just driving would throw errors. Since you are not getting errors and haven't had ABC blow-back from the dipstick, my guess is your accumulators are not the main issue. Replacement may be needed anyhow as they do leak nitrogen over time and replacing on a predetermined maintenance schedule is a good idea.

Of course this doesn't answer your initial question to the related problem which still needs to be explored.

biker349

thanks for the response. hopefully once i get the rear tires replaced we will have a better idea of what's going on, but i assume no abc warning lights and no codes on star and full fluid in reservoir and no leaks under the car is all good news.