w126 strut on w116 6.9...

[andy77]

I was told by the MB Classic Center the w126 strut will be the new replacement for the w116 strut because the w116 strut is so hard to find and or not made anymore, however, I am only finding the rear w126 strut

Will the rear w126 strut work on the front w116?

If not what would one do?


Thanks

[s class]

I am surprised at this.  According to the EPC, the W116 struts have NOT superceeded to W126 parts.  And the rear struts are completely different to the fronts and not interchangeable. 

I question the advice you have been given - who did you speak to at the classic centre?

As to what to do, you should provide your VIN to the classic centre and order the proper W116 units.  AFAIK they are all still available. 

[andy77]

What is AFAIK ?

I found the stock w116 6.9 struts but they are like 1000.00 usd per strut so $$$

One of my struts has to be replaced because its leaking and I was going to replace the others too

[s class]

AFAIK = As Far As I Know

I did tell you in one of your other threads that the struts were in the $1000 each vicinity.

The pennies are dropping for me now - you say you can only find rear W126 units?  I'm guessing that's because they are for the hybrid spring/hydraulic SLS arrangment found on the rear of most W126's.  If you can provide a part number or a link to these W126 struts we can confirm. 

SLS struts are completely different to 6.9 units.  6.9 stuts are pure hydraulic while SLS stuts rely on spring assistance.  I suspect the only place you will get proper 6.9 stuts is in fact the classic centre, or possibly Niemoeller - but the price is likely to be about the same anyway once shipping is factored in. 

[s class]

116 320 25 13 = hydropneumatic spring leg FRONT LEFT
116 320 38 13 = hydropneumatic spring leg FRONT LEFT SPORTY DRIVING

116 320 26 13 = hydropneumatic spring leg FRONT RIGHT
116 320 39 13 = hydropneumatic spring leg FRONT RIGHT SPORTY DRIVING

116 320 36 13 = hydropneumatic spring leg REAR LEFT OR RIGHT
116 320 37 13 = hydropneumatic spring leg REAR LEFT OR RIGHT SPORTY DRIVING

I think we have discussed this before and concluded that the sporty driving units are NLA - any other opinions on this?

[koan]

What is AFAIK ? As Far As I Know

I'd too would think they would be still available, don't get fobbed off by un-helpful dealers.

The $1000 per front strut sounds about right and that's price of owning hydro suspension.

I replaced my front pair, it made no difference to anything.

Just how bad is the leak, if it's only a bit of weeping don't worry about it. It's not like a leaking shock that will lose its oil.

koan

[andy77]

Thank you for all the info its great.

The leak is bad enough that the front driver wheel does not stay up as high as the rest.  In addition sometimes both front wheels are lower after the car has sat all night.

So I know I will replace that one and might as well do the other three for safeguards

[s class]

I second koan's question - how bad is the leak?

Struts can leak internally or externally.

Internal leakage is normal and by design - some fluid continually passes the seals and out via the leak line.  The workshop manual documents a procedure for measuring this fluid pass rate ("leak" rate) and provides specs on what is acceptable.

External leakage -  sweating is normal - only when you get puddles on the ground is it a problem.

I replaced all 4 struts in my blue car - yes - at $1000 each - and they all 4 do still pass fluid by internal leakage, and they all sweat.  After 5000 miles, the fronts are completely coated in an oily dusty goo.  

Its normal.  

[s class]

Some further thoughts for you -

Does this sinking in the front happen every night, or only occasionally?  If its occasionally only, then it might just be a dirt particle trapped in a valve.

If it sinks just the same every night, it could be either a leaking strut or a leaking level valve.  If this is the case, it is more likely to be the valve than the strut.  HOWEVER, all these components (valves, struts etc) are sufficiently expensive that using a parts-replacement approach to solving the problem is inadvisable.  Someone familiar with 6.9 suspension should be able to determine with confidence exactly where the problem lies. 

[koan]

The leak is bad enough that the front driver wheel does not stay up as high as the rest.  In addition sometimes both front wheels are lower after the car has sat all night.

Again I ask how bad is the leak?

Odd that one side should sink as both sides are connected together, any pressure loss in one side will be mirrored in the other side.

My car still sinks now and then even with the new front struts, the problem is not the struts in my case, most likely level valve.

Please see some expert advice from someone who knows these systems, not the guy down the road.

koan

[TJ 450]

The rear left strut on my 6.9 leaks externally, from the top screw-on cap o-ring. Even though the entire strut is wet, it makes no difference to the car's height... I can say the the car never drops, even when sitting for weeks at a time.

I would be looking at the offending strut very carefully, to see where it's leaking, as it might just be at the hose fitting or hydraulic line.

Yes, new struts would be nice, but that's a lot of money, especially if it's not the problem.

Tim

[rob1spi]

Have a look here. on page 6 http://www.starmotorsny.com/pdf/HydroSuspGuide.pdf.


"HYDROPNEUMATIC STRUTS:
The four-hydropnematic struts that are part of the 450SEL's 6.9 suspension are an item that has a
life span of approximately 10 years or 100,000 miles. The struts key failure areas are the nylon
seals and the 70 durometer rubber o-rings. These items fail due to heat and contamination. As
the strut moves up and down tremendous heat is generated and the rubber o-rings are literally
baked and unbaked. Overtime these o-rings loose there elasticity and start to collapse, thus
causing the oil leaks. The oil leaks show up in two ways; external and internal oil leaks. The
external oil leaks are visible at the bottom of the strut. Internal oil leaks are distributed back
through the return tube (D2) nd into the reservoir tank. This leak is less apparent but can be
measured by removing the D2 line connection, plastic tube, from the strut. A measurement of
2cc's in a 4 hour period or 6cc's in 12 hours. For simplicity, if you get a considerable amount of
fluid in a short time the struts are leaking and should be replaced to prevent further problems.
Contamination in the strut occurs from the rubber boots being torn and exposed to the elements.
The nylon seals (wipers) trap the road debris that enters the strut. Since the gap between the strut
cylinder is infintesimal, very little dirt is exposed to the seal. The main culprit is time and eventually
the seals were out. The rubber boots on the struts should never be comprised. Inspect and wash
them regularly, replace if they are torn. This will improve the longevity of the strut. The struts can
be rebuilt."

These guys seem to know there stuff.

Not to steel the thread but has anyone ever had struts rebuilt?

Rob.

[koan]

Have a look here. on page 6 http://www.starmotorsny.com/pdf/HydroSuspGuide.pdf.

These guys seem to know there stuff.

They certainly seem to but so do we. In practice unless the strut is leaking like a sieve its not a problem.

Not to steel the thread but has anyone ever had struts rebuilt?

Yeah, I'd like to know that too.

koan

[s class]

Well said koan. 

Between us on this forum we have seen ample cases of cars with 300 000km plus, still on original struts and no problems. 

GrantV was having a garage clearance this weekend, and I picked up from him an old partially disassembled strut.  I believe he was investigating the possibility of rebuilding it, and had it disassembled by some hydraulics place.  I'm not sure what the outcome was, but given that its still lying as a box of bits, I'm guessing they decided against rebuilding it.  I will try to get some photos of it.