News:

www.W116.org - By the people, for the people!

Main Menu

6.9 suspension problems - 6.9 newbie here

Started by s class, 05 September 2007, 04:31 PM

s class

OK guys, as it is now known, I'm the proud owner of a mechanically challenged 6.9.  Among other maladies, it has serious suspension issues. 

The front end sags a bit over night, and is allmost comletely down in 48 hours.  When starting from cold, the red suspension warning light takes about 30 seconds to go out. However the front doesn't lift up properly.

The front end feels very soft. I have to creep slowly (like 5km/h) over speed humps. If I try going any faster, after the front wheels get over the bump the front end of the car wallows up and down a couple of times, a bit like driving a conventional car with worn-out shock absorbers.  At driving speed (say 60 km/h) the car takes bumps in its stride - OK still a bit wallowy - its as if at the higher engine speeds, there is more pressure, or perhaps the pump is able to partially overcome pressure lost somewhere due to internal leaking?

The rear end feels a lot harder. When the car is idling, I can't really push down on the rear end at all. I'm guessing the rear spheres are gone, but what else?

There are no external leaks on the system. Does this sound like front struts? spheres? level valves?

I have checked and the left front sphere has a red mark on it, the rears have green marks (too lazy to check right front).  So far so good. 

The left front strut is marked 1163202613 - correct according to the EPC (standard not sport driving)
Rear struts are both 1163203613 - I don't have access to that listing on EPC so I can't confirm it they are correct.

The right front strut HAS NO MARKINGS AT ALL ????#

Both front struts have been seriously graunched by some massive visegrip or some such - see the photos below.  Has someone attempted to refurbish these?





Finally two questions :

a) how does one decide that a strut needs replacing?
b) how does one decide that a sphere needs replacing?

'spose I could also ask, how do I know my pump is OK?


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

koan


Thirty seconds to pump up from fully sagged sounds about right.

Your description of the ride sounds exactly like mine when I got it. It was rock hard at the back. speed bumps were murder, and like a small boat heading into the swell, five new spheres fixed that.

The cause of the sagging front could be an internal leak in a valve or strut(s). There is a leak down test for the struts in the manual that doesn't require tools apart from a spanner - I think it's in the library.

If there are visible leaks from the struts they should be replaced.

koan

Boogity, Boogity, Boogity, Amen!

s class

Thanks koan,

what you say makes sense to me.  Tomorrow I will look for that procedure of checking struts.  It will allow me to either prove or disprove the struts as a source of problems hopefully.  As to external leaks, I pressure cleaned the struts on Sunday, and have driven 50km since, without fresh leaking being apparent now. 

How many valves are there - are you referring to the front and rear level control items?

As to 30 secondsto pump up, well thats 30 seconds for the light to go out.  No length of time is enough to get it to rise up fully. 



[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

koan

Quote from: s class on 05 September 2007, 04:53 PM

It will allow me to either prove or disprove the struts as a source of problems hopefully.


The ride is spheres, no question.

Quote

How many valves are there - are you referring to the front and rear level control items?


Three, the combination regulator and control valve on the tank, and a level controller front and rear.

Quote

As to 30 secondsto pump up, well thats 30 seconds for the light to go out.  No length of time is enough to get it to rise up fully. 


The 30 seconds to light out is still about right.

If the front is not high enough it could be just the rod on the front level valve incorrectly set. If it rises at all, it should rise to the proper level.

You don't need more pressure to go higher, just more oil in the struts/spheres at the same pressure. Only if you add weight to the car do you need more pressure in the struts/spheres to support the extra weight.

Do the leak down test, the hydro suspension is covered in the online library, section 32, job 515 and up (the library is not working for me at the moment).

If you have a gross internal leak in a strut, more rpm gives more pump volume which might be enough to overcome the leak - if that what you are saying is happening.

If you were to disconnect the rod on the front level controller and move it by hand about 30 degrees either way (NEVER more than 45 degrees from center) you should be able to vary the height over the full range.

Same with rear controller but care is required to avoid an accident as the controller is under the car. Probably worth doing, I use a stick with a bit of bent tin on the end to move the rear lever so no part of me is under the car.

koan
Boogity, Boogity, Boogity, Amen!

Bandolero

Quote from: Patrick Bateman on 05 September 2007, 05:54 PM
there were a pair of brand new front struts for buy it now $700US on ebay not long ago, dont know if they are still there. They were from Lebanon, so i dont know how reliable their dodgy postal system is..

Andeas bought those and they arrived fast by DHL.
Russell Bond - (Adelaide, South Australia)
1978 450SEL 6.9 .... #5166 .... 12/78 (Sold.) [url="//www.ezycoat.com.au"]www.ezycoat.com.au[/url]

s class

Thanks guys - I will investigate probably on the weekend.  At present the car is on stands with - er - brake failure.  It was quite specatular too - no body damage done...... - see thread on brakes


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

CraigS

If it is the guy in Lebanon I am thinking it is, he is very reliable. He spent quite a number of years in the US, selling Mercedes parts.

Quote from: Patrick Bateman on 05 September 2007, 05:54 PM
The rear strut part numbers are correct for non sporty driving 6.9.

with those front struts, it certainly does look like some butcher has cracked them open to take a peek inside. I'm almost certain they'd be stuffed.


there were a pair of brand new front struts for buy it now $700US on ebay not long ago, dont know if they are still there. They were from Lebanon, so i dont know how reliable their dodgy postal system is..
[url="http://s109.photobucket.com/albums/n77/Aegeanfoods/My%20Cars/"]http://s109.photobucket.com/albums/n77/Aegeanfoods/My%20Cars/[/url]

CraigS

I'm sure Styria would be happly to supply 2 reconditioned ones ! Even with the postage cost, it is probably still going to be cheaper than new ones.

Quote from: Patrick Bateman on 05 September 2007, 05:54 PM

with those front struts, it certainly does look like some butcher has cracked them open to take a peek inside. I'm almost certain they'd be stuffed.



[url="http://s109.photobucket.com/albums/n77/Aegeanfoods/My%20Cars/"]http://s109.photobucket.com/albums/n77/Aegeanfoods/My%20Cars/[/url]

s class

Thanks styria,

I fully appreciate the magnitude of the project I'm up against - and hes it is a grotty spade to be sure.

I will asap b ordering new spheres - I just don't fancy the dealer price and I'm waiting for Niemoeller.

BTW, the dealer listed 126.... numbers for the spheres - I know this issue has comeup before - have the 6.9 items been superceeded by 560SEL items?


To test the struts I assume the car needs to be resting on its wheels - presumably though I could check all 4 corners over the same 24 hour period?  I can't access the library due to some issues with macromedia flash player....

I will have to wait until the car is back on the ground after the brake work. 

As to the pump, yes I feared that it is below par.  Is it an issue of seals, or do the mechanicals wear?  I know the same pumps are found on other 116's with selflevelling, buy none of the locally made 116's had self levelling - so no pumps at the breaker's yards - UNLESS - did the W123 300TE perhaps use the same pump??

Yes I have bought a new hydraulic filter and oil, but given the cost of the oil I'm not using it until I've replaced the spheres/struts/whatever else is needed. 

When the engine is off, the rear is like waterbed - the front not so becuase it is just down.......

styria you don't mention the levelling valves - are they not such a likely suspect?


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

oscar

sclass, re the pump, w123's used the same as did w126's.  At least they look identical.  And the seal kits are advertised for the same.  You wont do any harm IMO by fitting another.  If it's in good nic, it'll either work or it wont and wont do any harm.

Another little bit of info.  Have you got the Haynes 350/450 manual?  Chapter 11B which is only 3-4 pages long covers the 6.9 hydropneumatic system.  I don't know why but it's there and doesn't mention the 6.9 persay, it just says some w116's have this system and it's not referring to rear self levelling.  It's got a good schematic and some handy tech specs like flow rate of the pump.  If you haven't got it I'll email the pages to you.

1973 350SE, my first & fave

s class

thanks Oscar - I don't have that manual. You have my email address? - just make sure that each mail does not exceed 2mb otherwise the firewall will kick it back. 

Great to know maybe I can use a 126 pump, bacause a lot of the late 126's here had self-levelling.

There is some hope


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

oscar

Yep!  If I finish on time tonight, expect an email around 4-5 hours after this post.
1973 350SE, my first & fave

s class

I have in my grubby little paws a nice suspension pump that I got off a late W126 420SE with lowish mileage and no tow-bar.  It was the most promising one I could find. 

We'll see in the next few days. 


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

s class

Thanks styria, I'm also just itching to do the leak test on the struts but I have to wait till I've finished the brakes.


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

koan

I did a bit of work on my crap brakes today, when finished the car was on it's knees front and rear giving me an opportunity to time the pump up. I depressed the suspension completely by moving the rotary lever to the 4th position and back.

The engine was at cold idle, about 1000 RPM, from starting the engine to light out was around 38 seconds, the car didn't start to rise until after about a further 5 seconds and was at normal height  in around 4 more seconds.

This is all on a new pump that would have done 15k at the most and as never run dry.

So it does take awhile for a completely depressed suspension to get to normal height.

koan
Boogity, Boogity, Boogity, Amen!