W124 '95 E280 4 Spd Auto Est / Suspension Hydraulics

[JensH]

Mornin' all,

Not posted for a while, because I have been enjoying several 1,000s miles of trouble-free, if high fuel consumption, motoring (well allowing for indicators packing up (fuse) and mystery flashing recirculation button, on Diavia A/C system).

Now, though, I appear to be having rear suspension issues - a bugbear of many a T-model owner!

Over the last month my ride has become very bouncy at the rear. This followed a month of driving in Europe on higher tyre pressure, and possibly, borderline loading on outward/return trips - I suspect this means the shear pin may have gone in the hydraulic pump? There were no symptoms, before this trip - 3,000 miles in about 6 weeks. During this trip I also had seven aboard on several occasions.

Generally the handling is fine, except after a bump, when the car frequently (not always) sets into a wobbly (and car sickness-inducing) bouncing. This always settles down, but in London, with all its traffic calming, it is a nuisance. In-car conversation during the bouncing assumes a slight vibrato...

On my last (144k 'B') service a couple of weeks back, Autodeutsche (Camden) confirmed my own thoughts, which is that it was the gas spheres on the rear axle. Car had lost hydraulic fluid. They also suggested that I should replace struts and springs at the same time as doing the spheres - £800 before parts, which I would source myself, so an expensive fix. The also made muttering noises about complications from corroded bolts (meaning the "fix" may damage the hard pipe lines).

Yesterday I ran diagnostics with my little flashing gizmo. This threw up only two codes: for the left and right rear axle solenoid valves. All else clear.

I have no issues with power steering or other hydraulic functions.

My questions:

1) If the pin is sheared, is there a simple fix or is it always a new pump?

2) How can I test for a failed shearpin?

3) If I do the recommended rear axle work, should this be with genuine MB parts or are there aftermarket options, or could I use s/hand recons? - I have several reliable sources for parts of each type...

4) Anyone any other ideas?

Cheers all,


Jens

 

[star]

Is it bouncy as in soft or too firm as in no give. If the latter, then I would say your spheres have failed.

 

[hotrodder]

Hard / bouncy ride = dead spheres as they do virtually all the springing and damping... when the membrane in the spheres is ruptured the fluid level in the resevoir will drop a noticable amount as the space previously occupied by nitrogen is filled with incompressible oil

Why do Autodeutsche want to replace the struts and coil springs? The struts are basically just hydraulic rams, physical damage aside the only reason to would be that they're leaking i.e. instead of the normal oily film on the piston rod they're actually dripping wet. The coil springs just set the basic ride height, unless they're broken/heavily corroded replacing 'em seems pointless to me

Don't get the fault codes, the SLS system is purely mechanical/hydraulic on these, do you have ASR or ASD?

1) dunno but if it sheared due to the pump seizing then replacment with a used one is what i'd do
2) when the engine's running the pump should be running i.e. fluid is constantly sent around the system and the SLS valve directs some of it (according to the instructions it receives from the linkage on the rear anti roll bar) to the struts when needed and returns the rest to the resevoir through the screwcap which contains the filter
3) Used spheres would be a false economy IMO, I bought Febi ones from Wunderpartz when i did the back of mine* who were significantly cheaper than all the other usual suspects and a pleasure to deal with. If i needed coil springs i'd go to the stealer but don't ask them to quote for the struts unless you're sitting down and well medicated!! If you haven't got the sport chassis Sachs (102-811 i think, aka Boge 36-b07 0) do them for less than half the ££££ MB want but personally i'd price used ones first

* i dropped the subframe to replace all the pipework inc brakes and fuel lines and a bunch of other stuff at the same time. Zero seized fasteners but that was probably as the pipes were destined for the bin anway! If i had just wanted to swap out the spheres i'd have gone nuts with some plusgas a day or so before attacking it

 

[syncropaddy]

Never heard of the 'sheared pin' thing before but your symptoms are knackered spheres. There is no need to replace the struts or springs unless you have 200,000 + miles on the clock but I'll wager that you will have to replace a pipe or two. If you have to replace any pipes around the rear, dont faff about trying to wiggle them around the rear subframe, just drop the frame and make life easy for yourself.

The pump powers your steering as well as your SLS by the way

 

[JensH]

Thanks all, for the replies,

Having checked the hydraulic fluid the level has held up since Autodeutsche topped up on 20 October, although there is some evidence of seeping on the hydraulic reservoir supply line to the pump. Pump appears functional. No change in the bouncing, though. I know that if the SLS fails in the pump, it does not affect the pump operation of the PAS - I have no ASR or ASD, as far as I know; it's not on my factory data card.

I thought maybe a failed shearpin could be fixed, but seems not. I also read that the link rods can be manually set too (have downloaded stuff from USA site W124zone), so may read further on that (bearing in mind the car was fine before the high mileage, high load summer).

Since I am at 145k miles now, I'll take on board the advice about the life left in the springs and struts (to ca. 200k). I seem therefore to be looking at new spheres, with the likelihood of some new hard pipework in the process.

Labour is for the workshop. I stay away from the underneath and major mechanics! But will pass on tip about the subframe.

Will update when sorted...

Cheers!

Jens

 

[syncropaddy]

Please do update us on this

 

[JensH]

Please do update us on this

Wilco

 

[JensH]

That update...

Please do update us on this

Happy to report suspension issues resolved.

Ordered new springs, spheres, spring bushes and hydraulic pipes and fluid from MB Specialist, along with outside lower edge seals for front windows, whilst I was at it. Using the EPC I calculated the specification for the spring bushes, including allowing for the after market air-con and, as a result, ordered the beefier size.

Then a recon set of shocks and new fitting kits from German SPOB.

All fitted by Autodeutsche in Camden last week and, after a few days, I can confirm the car is driving/handling like new, so all good. It is a little stiffer because of the new fatter bushes and is even sitting a few millimetres higher at the back, as per attached image.

The shop fitted the seals FOC and that has pretty-much cleared up my condensation issues. Amazing what a 10-15 mm gap in a seal can cause...

Basically, all the restoration is done now, so, (touch wood!) the car just needs maintenance and odd bit of cosmetic attention.