my 6.9 can't get it up !

[B13]

Front suspension that is....

The car's not undrivable, just very low at the front. When it used to do this I'd just drive and within a few km the front would pressurise and lift up.

The rear is fine - never sinks or does anything stupid. In fact has been perfect from day 1.

Recent stuff that has changed in the last 6 months:

1. Pressure warning light no longer illuminates ever... used to come on when I pulled out the height adjust knob, or when the front went down it would illuminate until the system had pressurised.

2. The annoying LH front corner hydro-fluid leak as mysteriously gone away... yes the tank is full of hydro fluid...

Des can you help me here?, I need to confirm what was changed during your ownership of the car... if memory serves its the 5 spheres, rear hydro struts, and control valve... Since I've had it I've changed the hydro-pump.

The front height control valve looks funky and the rod coming from it is not longer parallel to the ground L-R anymore.

I thought the hydro system on 6.9s, at least by 1979, was self-bleeding (just drive the car vigorously for a while)? Also when the suspension did pressurise at the front properly, all 5 spheres and 4 hydro-struts behaved as they should, giving the normal 6.9 magic-carpet type ride.

Help?

Ian.

 

[Des]

Dear Ian

Do you have all the paperwork there that I gave you for the car, should list what was done?

From memory, 5 spheres were changed, was 1 or maybe 2 struts in the front changed

the valves were rebuilt? or something done to them?

the pump seal was changed, or the pump filter when the timing chain was done, as it had to come off, and it was leaking so had to go back a few times for the seal to be done...again
thats what caused some of my problems, leaking pump,


I never had problems with the back sinking it was always the front too, it would sink and look like a drag car, with the back up in the air.

but when it would sink, the light would be on, start it up, rev it for 30-seconds to 1 minute and it would raise itself




mate I really need to get off my backside and find that book for you,

so you can diagnoise the problems and read the book

let me get onto that tomorrow morning

 

[Des]

I thought the hydro system on 6.9s, at least by 1979, was self-bleeding (just drive the car vigorously for a while)? Also when the suspension did pressurise at the front properly, all 5 spheres and 4 hydro-struts behaved as they should, giving the normal 6.9 magic-carpet type ride.

Help?

Ian.

No to bleed the system you need to undo the big nut on top of the main distribution valve, its like a 12mm nut from memory
Styria once very kindly went through it with me over the phone, you undo that, it is where the metal plate is for the height adjustment, and let the air escape, rev it up with the nut undone, once when I undid mine it let out a big "hiss" of air as it escaped from the system.

 

[TJ 450]

Bleeding the system there sounds a bit risky to me... Did this occur whilst driving? Is the distribution valve cable adjusted properly?

Tim

 

[B13]

Did this occur whilst driving? Is the distribution valve cable adjusted properly?

The cable is adjusted properly. The car has a propensity to sink at the front overnight... not every night, just randomly, and as Des said, you start it and in a short amount of time it lifts again.... basically since the onset of winter its gone down and stayed down...

The height adjuster has never worked (pull it to the 2nd detent and the light used to come on but no matter how long you waited or drive the car would never raise), but this has never been an issue for me since I don't need the car any higher than its normal height ever.

The system must be partially pressuring at least because the back never goes down, or if I jack the back of the car up to change a wheel / inspect brake pads, when I lower the car it does lower incredibly low, but start and run for a few mins and the back lifts again.

Given that the spheres, struts, pump and control valve all should be in good shape, I can only think it must be the front level valve... which was curiously the thing which gave me greif on my last 6.9

I.

 

[Des]

Sounds like whatever it is, has been getting worse, for me the car would sink somewhere between 1 - 2 weeks,
if i started it up every week it would always stay up.


however someone once mentioned over on the M100 forum that if the car gets cold, i.e. winter it will cause the fluid to do "something" I can't remember what and cause a car to sink.



always the back would stay up for me


also I could get the car to raise itself with the dash lever, and lock the suspension from the knob, sounds like something has got broken there?


check your email Ian, I just sent you something that hopefully can assist.


Kind Regards
Des

 

[TJ 450]

Ahh, I see.

It does sound like the front leveling valve is allowing the pressure to bleed back to the reservoir. This is what my car was doing, but the problem stopped when I changed the fluid, perhaps there was some sediment in the check valve.

Tim

 

[Lukas]

For what it's worth, in the short time I've had the 6.9, it has lowered at the front one or two times, but apart from that the front stays up. Back is always up. Circumstances:

* Car is only ever run for up to 10 minutes, either weekly or fortnightly (no rego, so can't drive it anywhere yet)

* If it has dropped, front lifts within 30 secs of starting the engine

* When the front has lowered, it does seem to have been over the colder weeks (down to -4 or so at night, about +10 during the day)

* Time does not seem to be a factor in the front dropping - mostly it stays up just fine, apart from when it's cold(er)

* There is a small hydro fluid leak above the front LH strut in the plumbing somewhere - that strut has been replaced recently, as have all 5 spheres.

If the cold does affect the fluid (possibly exascerbated by dirty fluid gumming up the valve), that would explain the erratic nature of the front of my one dropping too.

Lukas

 

[B13]

Lukas,

Its my (limited) experience that most (well maybe not most, but probably 1/2) exhibit the same behaviour as you describe. It describes my previous 6.9 perfectly, and to be honest, I drove it that way for 5 years and it never failed to lift in the mornings. And in fact its perfectly livable with that way as well... if I can get my current 6.9 to that condition (if not better) then I will be more than happy.

Lots of people who have 6.9s that don't sink often have a fully refurbished hydro system with no expense spared so you would imagine the system to function perfectly for a decade or more (s class, michel and styria spring quickly to mind). But most of us with daily-driven 6.9s know they are apt to some eccentric behaviour at times.

Godfather, when you are back I need to talk to you about a front level control valve and a control valve.

Here's how she's currently sitting (yes I know, rare to find these days, that is indeed a topless calendar hung on the wall in my garage):

I.

 

[Des]

Have you changed the tyres?
Because if the BBS's fitted there was bugger all clearance between the guards and the tyres?
I was always worried if or when it sank they would dig into the guards and bend them again.

 

[John S]

It's not something very simple is it, like the lever coming loose from the valve under the bonnet? Or does this lever affect all 4 wheels equally?

 

[B13]

Hi John, I've checked all the basics, like for leaks, and loose rods etc.

I'll do a more intensive search on the weekend.

Hey Des it looks like some of the pictures you took of it at the shopping centre in tassie, doesn't it? No when the front lifts properly there is ample clearance at the front for those big 245 tyres.

I'm also keen to diagone the warning light. If things aren't right I'd prefer the light to be telling me things aren't right, rather than staying off telling me everything's cool, when its not.

I.

 

[BAR]

I am no expert in the MB hydraulic system, but I have 2 decades of experience ownig 6 Citroens.

In the Citroen, when parked and level, without the hand brake applied and with the ignition switched off the whole car would sink overnight. The car would remian stable for a short time only because the pressure valve was presumably wired into the ignition somehow. This was the case for those vehicles simply to prevent fluid leaking with the system remaining pressurised for long periods of time.

In the case of your car, there may be an issue with a pressure release valve being contaminated and thus remaining partially opened allowing the car to sink, either after a short while when the engine isn't running or even when at idle.

It may also explain why you do not get the correct result when engaging the heght selector lever.

 

[B13]

I guess its wishful thinking but does anyone know whether either:

Will a rear SLS valve from a regular W116 work up front as front level control valve, or are they different part numbers?

or

Will a front level control valve from a W126 fit? If so which model W126s came with them and is anything special needed to fit one into the old-timer?

Thx.

Ian.

 

[TJ 450]

Only a front leveling valve from a W126 with full hydropneumatic suspension will fit other than the unit specified for the 6.9. The device itself is actually not that complicated, it should be rebuildable. It may just need flushing out.
The SLS valve is quite a different beast and will not work AFAIK.

Tim

 

[SELfor50]

Have you tried putting some viagra into the hydro fluid??

...yeah, sorry, i got no idea..

 

[Styria]

Hi B13, you'll need to give me a couple of weeks. There are other 6.9's running around with the same problem. It takes a bit of working out which components are at fault. TJ 450's info is spot on. I doubt whether you'd find any 560's with the hydraulic set up. Regards Styria

 

[B13]

Have you tried putting some viagra into the hydro fluid??

Word.... i suppose the 116 is a bit like the granddaddy of the road....

Still not getting many of the W116 waves from other 116 owners, nor 108 owners, but sometimes 126 owners do...

Ian.

 

[Des]

Sounds like you need some emergency rubber suspension blocks Ian.

At least then the car would be moveable

 

[B13]

I'm still driving it at the moment, the area between here and work is remarkably free of bumps, undulations, speed humps.

There's only one or two places where I can here a pronounced rub of the tyre against the guard.

Unfortunately this is the only car I can use to I just have to take it easy.

I.