W124 300TD Estate Suspension Question

[Donald]

First of all i just want to say Hello!

I recently bought myself a 1992 W124 300TD Estate.The car is flawless apart from the rear suspension.It sits really low at the back.The previous owner told me it probably needs new rear shocks but having read through the forums on here i'm slightly stumped as my car has self levelling suspension.I rarely have any more than two people in my car so is it possible to fit standard shocks from a saloon or do i have to bit the bullet and fit either new shocks or new "spheres"??? If there is another cause to why my car sits low at the back please let me know.

All replies would be appreciated (bear in mind i'm new to mercedes,my previous cars were a Vauxhall and Fiat! )

Thanks

Donald

 

[Druk]

Hello Donald.

First thing to check is the condition of the small link arm which goes from the rear anti-roll bar to the levelling valve. If this has popped its ball joint from one end the car will sit at whatever attitude the arm rests at. Look up near the diff O/S rear. If that is OK then it may be you need new spheres. Ordinary shocks will not work.
Have you checked the oil level in the tank?

 

[Mercedes cozy]

if the rear is a bit bouncy at the back then it could be the spheres

 

[bolide]

The car should sit at the "right" height when parked - that height is set by the springs. If it's sitting markedly lower at the back than the front then something is amiss - probably a broken spring

On the road, ride height is kept correct by the height corrector activating the self-levelling if the height is wrong. The linkage to the height corrector (see Druk's post) is therefore key to this

If it doesn't self-level you have a self-levelling problem. If the rear is excessively hard or excessively bouncy you need new spheres

The rear of the car does not have conventional shock absorbers - it has a Citroen-like hydraulic system

Nick Froome
www.w124.co.uk

 

[Donald]

The car handles fine and is not bouncy or hard (ooh er!) As a novice to Mercedes cars where is the tank to check for the level.I have attached a picture to see if you guys thinks it sitting too low at the back.I'm off work tomor so plenty of time have a look over the car.

 

[stumpy1]

Doesn't look right to me. Get the back wheels up on some ramps and check the link arm to the valve. The springs should hold the weight of the car with the arm off / engine off. If that link arm has popped off and the valve arm is out of position it will force the struts to compress / extend the springs.

 

[Dieselman]

it will force the struts to compress / extend the springs.

It can't compress the springs.

 

[stumpy1]

It can't compress the springs.

What was it doing to me the other day then? I took the arm off, wiggled the valve and the thing shot down pdq.

 

[Dieselman]

Gravity was pulling the car down, they are hydraulic rams only fed from one end, so cannot press against the spring.

 

[stumpy1]

Gravity was pulling the car down, they are hydraulic rams only fed from one end, so cannot press against the spring.

I see, so with the arm off / engine off the height is 'kept' by the px locked into the ram position. You learn something new.............

eta, therefore the springs don't take any weight of the car

 

[Dieselman]

I suspect your springs are in less than perfect condition so allowing significant sag to take place.

 

[stumpy1]

only done 128k miles though.

 

[Druk]

The hydraulics do take some of the weight IMHO. I renewed the spheres years ago on a 124 te and the rear end stayed low until the engine started and the air was expelled from the system.

 

[Donald]

So what you guys reckon,check the link arm 1st but possibly the springs?

 

[bolide]

The front looks quite high - as though the springs have been replaced - and the back looks a tad low - as though they haven't

A quick look at the front springs should tell you if they're newish. Have a look through the history and I'd guess there will be a spring replacement roundabout MOT time, probably due to a breakage

Other than that, follow the other posts

Nick Froome
www.w124.co.uk

 

[Donald]

Nice one thanks guys,i'll have a nosey over the car tomor and report back.Thanks for the warm welcome and supportive comments.

 

[Donald]

School Boy Error

I should have checked this first

Just opened the fluid reservoir to find that there is very little oil,maybe about 2mm on the end of the dipstick,no where near the min mark.There does'nt appear to be any fluid leaking so maybe it has entered the spheres???

What fluid can i top this up with and is it available from a motor factors or even Halfords?

thanks

 

[andy_k]

you need a specific spec hydraulic fluid which can be bought from either GSF or the dealers - GSF is considerably cheaper.

Once you've filled it up check the system for leaks

If the rear of the car feels harsh over bumps then it's probably the sphere's - you can release a small amount of fluid from the system - loosen one of the feeds to the struts - if it's milky then it's been mixed with the nitrogen from the spheres

 

[Donald]

Theres no alternative i could use? the nearest dealer is 50 miles away

 

[andy_k]

you can buy on line with GSF

http://www.gsfcarparts.com/index.html

you need part number M98001