Author Topic: Replacing 6.9 accumulators - any recent experiences?  (Read 275 times)

raueda1

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Replacing 6.9 accumulators - any recent experiences?
« on: 29 February 2020, 11:20 AM »
Just doing it "because" . . . .   the car is up on a lift so easy access at the moment, seems like a good idea to start fresh in advance of future problems, etc etc.  Anyway, it seems like the front accumulators are easily available from AutohausAZ parts and others.  The rear accumulators seem harder to find.  There seems to be lot of stuff on eBay, though much is from China with uncertain pedigree.  I may try the Classic Center though I suspect they'd be on the expensive side. 

Has anybody done this recently with info to share?  Any opinions on the Corteco products?  Finally, my ride seems OK - car rises, handles fine (as far as I know), comfortable and smooth.  But I don't have a great basis for comparison.  Does ride quality slowly deteriorate as accumulators age?  That is, might new accumulators provide an incremental improvement in ride quality over still-functional but old accumulators?  Or is the effect of aging more binary, such that the ride is fine until all of a sudden it isn't?

Any comments appreciated.  Cheers,
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

daantjie

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Re: Replacing 6.9 accumulators - any recent experiences?
« Reply #1 on: 29 February 2020, 12:09 PM »
Dave I don't have first hand experience with Corteco but everything I've read on them appears to indicate they are top notch quality. Maybe price them out at the Classic Centre too.  Sometimes the MB parts are surprisingly well priced.
Daniel
1977 450 SEL 6.9 - Astralsilber

Jed

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Re: Replacing 6.9 accumulators - any recent experiences?
« Reply #2 on: 29 February 2020, 03:04 PM »
Hi dave, Ive done this job twice on two separate cars.  First one was obvious that that accumulators were bad.  It bounced like a trampoline.  Was basically not drivable. 

The second one was not bad but clearly there had been deterioration enough that the ride was getting bouncy...probably had one of the spheres bad so I changed all 5.

I bought my spheres from eBay, a seller called partscontainer.  I ve purchased from them many times and they are top notch with great pricing. Not sure if they still sell them.

I am not expert, but I think its an all or none thing.  I think they are either working with intact diaphragms or one or more have ruptured diaphragms and you will likely feel it. Not a hard job but not a job I would do to just do.....my advice, if the ride is nice and smooth leave it alone.  On the other hand if the car is bouncing a little over bumps in the road (kind of like a car with shocks that are wearing out or shot) then its time.



1979 Mercedes 6.9 #5206 - restored
1979 Mercedes 6.9 #6424 - ongoing restoration
1976 Mercedes 6.9 #484 - restoration?

slfan

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Re: Replacing 6.9 accumulators - any recent experiences?
« Reply #3 on: 29 February 2020, 04:25 PM »

I purchased my 6.9 five years ago and have no idea when the previous owner replaced the accumulators.  I am planning to this since my car’s has begun to get “bouncy”.  Could somebody share the part number for these?

Additionally, any recommendations where I can source good quality ones with a good cost benefit?  All suggestions are appreciated.

Best regards,
Angel
1978 - 450SEL 6.9 - 3170
1978 - 450SEL 6.9 "Parts Car" - 2973

UTn_boy

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Re: Replacing 6.9 accumulators - any recent experiences?
« Reply #4 on: 29 February 2020, 07:01 PM »
When accumulators go bad the car doesn't become bouncy.  It becomes very stiff in that it rides like there is nothing between you and the road.  It rides very hard/stiff.  If the car is bouncy then there there is air in the system or the system hadn't been bled properly.  Corteco brand accumulators are top notch in my opinion.  I've used 4 or 5 sets on various W116, W126, and W123 cars over the last several years.  So far, 5 years later, the first set I put on are still holding up well.  It's said that the accumulators have a life expectancy of 5-7 years.  If history is correct, then I'm ok with that.  And bear in mind that not a lot of miles will shorten their life.  Likewise, avoiding putting miles on the car won't lengthen their life.  It's time that kills them.....something we can't seem to harness. 
1966 250se coupe`, black/dark green leather
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1971 300sel 6.3, papyrus white/dark red leather
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1976 280s astral silver/blue MB Tex

raueda1

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Re: Replacing 6.9 accumulators - any recent experiences?
« Reply #5 on: 01 March 2020, 07:29 AM »
Thanks for the remarks, very helpful.  Sounds like they're good until they're not, so I'm going to just leave them alone for now.  To slfan, sorry, I don't have part numbers.  But the Corteco spheres are all over eBay, no problem finding the right ones.
-Dave
Now:  '76 6.9 Euro
Before that:  1966 230S, 1964 220SE coupe, 1977 Carrera 3.0

slfan

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Re: Replacing 6.9 accumulators - any recent experiences?
« Reply #6 on: 02 March 2020, 04:50 PM »
When accumulators go bad the car doesn't become bouncy.  It becomes very stiff in that it rides like there is nothing between you and the road.  It rides very hard/stiff.  If the car is bouncy then there there is air in the system or the system hadn't been bled properly.  Corteco brand accumulators are top notch in my opinion.  I've used 4 or 5 sets on various W116, W126, and W123 cars over the last several years.  So far, 5 years later, the first set I put on are still holding up well.  It's said that the accumulators have a life expectancy of 5-7 years.  If history is correct, then I'm ok with that.  And bear in mind that not a lot of miles will shorten their life.  Likewise, avoiding putting miles on the car won't lengthen their life.  It's time that kills them.....something we can't seem to harness.

Okay. Thank you for the information.  Will look into this. Best regards
1978 - 450SEL 6.9 - 3170
1978 - 450SEL 6.9 "Parts Car" - 2973

TJ 450

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Re: Replacing 6.9 accumulators - any recent experiences?
« Reply #7 on: 02 March 2020, 09:49 PM »
Allegedly there is this in-between phase where as the gas is bled off through the perished diaphragm it aerates the fluid leading to a bouncy ride.

The spheres on my car are now 10 years / 60,000km old and the ride is a bit bouncy at times but not rock solid yet.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

Jed

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Re: Replacing 6.9 accumulators - any recent experiences?
« Reply #8 on: 03 March 2020, 03:41 PM »
Yes Tim, I would agree.  I was thinking about this last night as I read the above posts.  Again, I am just a shade tree mechanic, no expert, and almost all I have to go by is my experience which is VERY limited...but I would think that when the diaphragm ruptures its going to leak the nitrogen which may be the "air" or gas in the system that causes the bouncing? Maybe temporarily before the ride gets firm/hard?

I have previously found the troubleshooting guide posted by Star Motors on their website very helpful which also suggests that a bouncy ride means failed accumulators (page 5).

https://starmotorsny.com/wp-content/uploads/2013/02/ser-HydroSuspGuide.pdf

All that said, I would ultimately defer to Aaron, as I have always found his insight and expertise to border on gospel.

Jed

1979 Mercedes 6.9 #5206 - restored
1979 Mercedes 6.9 #6424 - ongoing restoration
1976 Mercedes 6.9 #484 - restoration?

Punker

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Re: Replacing 6.9 accumulators - any recent experiences?
« Reply #9 on: 04 March 2020, 12:36 PM »
I changed all 5 accumulators on my 6.9 and used FEBI. They were ok too.
Greetings
Björn
1978 Mercedes 6.9 # 4616 - black/black leather
BMW R 25/3

Randys01

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Re: Replacing 6.9 accumulators - any recent experiences?
« Reply #10 on: 06 March 2020, 10:37 PM »
There is definitely a ridiculous bouncy phase. Mine were shot when I bought the car 15 years ago. I drove it a long distance to bring it home and I did 200 vertical miles versus 6oo  along the road!
The units were replaced and viva la difference. However here we are and in the last year, the bounce has returned . The car has done little miles in that time and again, perishment is more a victim of time than distance.
I have a friend up the road with  a 6.9 and a year ago his exhibited the same "do you think this car is a bit bouncy?" to "crikey hang on before we fly thru the sun roof." in a period of only a couple of months.

Jed

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Re: Replacing 6.9 accumulators - any recent experiences?
« Reply #11 on: 07 March 2020, 06:49 AM »
Randy, that is exactly the bounce I experienced when I drove a 6.9 home for the first time a few years ago.  Pogo stick-like bouncing.  In fact, and this is purely speculative, I think the internal force on the hydraulic system from the repetitive bouncing caused the hydraulic line from the pump to the reservoir to burst, as by the time I got home there was a healthy leak that developed from this high pressure hose which required replacement....or maybe the hose was just really old and decided it had had enough.
1979 Mercedes 6.9 #5206 - restored
1979 Mercedes 6.9 #6424 - ongoing restoration
1976 Mercedes 6.9 #484 - restoration?

nathan

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Re: Replacing 6.9 accumulators - any recent experiences?
« Reply #12 on: 07 March 2020, 03:44 PM »
Ive had the lemfoerder traditionally, but last time had the corteco's.  they seem fine after 3 years.  they last about 7 years is the word, and in my 20 years I've changed them twice.  I just get all 5 done in the one go, no point half arsing and getting annoyed one year later when the others are done!  Id go straight to the classic centre, I can't imagine they are. a lot more expensive and you know what you are getting.  here is a video of the 123 Wagen I changed the rears on last year I think (obviously only has the rears)
https://www.youtube.com/watch?v=0bJgGRJkdiA&t=10s
6.9 79 #6436
6.9 79 #6290
6.9 79 #6181
6.9 78 #4764
6.9 77 #3096
6.9 76 #1741
6.9 76 #0902
6.9 75 #0018