Tires, Brakes and Suspension

I have been working on my project car this winter.

I assume the car was not driven for 6 or even 8 months when I got it from the shipping company who transported it from the USA to Finland. Back in the U.S. the car was still on the road but being hard on the suspension.

The nose was down when I got the car and after starting the motor the front pumped up. I drove the car for approx 10 kilometres and everything was ok with the driving besides very hard suspension.

I replaced all the 5 speheres; the left hand side was ok, the rest 4 were completely broken.

I replaced the fluid and the small filter cartridge at the main valve. I did not manage to get the "golden" (sintered) filter out from its bore but I cleaned the most of the crud away that was visible. I bled the pump by directing the outlet hose into the fluid reservoir.

Now I have a problem to raise the car. First nothing happened despite I ran the motor for some time. I bled the front at the nipple under the battery. I left the nipple slightly open and saw a lot s of air coming out in intervals; the air came out when idling, then it stopped. Then when revving all the bubbles came out and the fluid was clear. After a while at idle the air came out again for 20 seconds, and I repeated this procedure for an hour. I recycled apprix 3 litres of fluid by this method. After having done this I saw the front was up, I am not sure if it is completely up but I can feel the front "is suspended" i.e. I can bounce the front end with my weight.

The rear is still problem, it raised for couple of centimeters but not more. I opened the rear bleeding nipple a bit and bled again approx 3 litres out. The rear raised for about 3 -4 centimetres. When I opened the bleeding nipple more the rear sinks and when closing it raises again but not more that 3-4 centimetres.

Last night is ran the motor when trying to raise the car for about 6 hours! I also lifted the rear by the US style bumber several times with a hydraulic jack, but no help.

Also high position does not help. Actually the car could not raise to the high position before I started to work on the car.

Front is harder now, the rear is actually very soft so it seems the fluid/pressure does not go all the way to the sphreres.

I did not touch the levelling valves.

Kari Pykäläinen

1971 6.3 #5581
1980 6.9 #7201
1981 380 SL
1987 560 SEC
1996 C180 A
1998 ML 320
1980 Stingray SV175 boat
http://suomi.mercedes-benz-clubs.com/

Stand on the bumper and start jumping.

With best regards

Al

Thanks Al for advice! I will try it [:)]

Can this be true, according to the pdf the high position was disabled in the US cars [:0][:0][:0]

http://starmotorsny.com/wp-content/uploads/2013/02/ser-HydroSuspGuide.pdf



Kari Pykäläinen

1971 6.3 #5581
1980 6.9 #7201
1981 380 SL
1987 560 SEC
1996 C180 A
1998 ML 320
1980 Stingray SV175 boat
http://suomi.mercedes-benz-clubs.com/

I have been jumping like a rabbit, no help. In fact the front is not either at normal height, I saw that when I drove the car away from the wooden blocks that we under the tires.

The car is on the floor now and definitely the front is also lower than before the overhaul. The middle muffler has only 20 mm clearance to the floor so it is too less.

The red light does not come on, except when turning the ignition on (before starting).

Kari Pykäläinen

1971 6.3 #5581
1980 6.9 #7201
1987 560 SEC
1996 C180 A
1998 ML 320
1980 Stingray SV175 boat
http://suomi.mercedes-benz-clubs.com/

You did your bleeding with the wheels off the ground so that they dangled (full deflection), right? And the plastic ends of each of the control rods are intact and properly connected?

-CTH

quote:

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Originally posted by cth350

You did your bleeding with the wheels off the ground so that they dangled (full deflection), right? And the plastic ends of each of the control rods are intact and properly connected?

-CTH

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No, the wheels were off groud when the car was on jack stands. I did the bleeding only after lowering the car on the wheels. So I should do it again, and raise the car when doing the bleeding? But, when the car is raised from the body the struts will be emptied by the levelling valves as they see already "high position"?

The control arms at the levelling valves look right, I have not checked those properly as I did not touch the valves and linkages.

Kari Pykäläinen

1971 6.3 #5581
1980 6.9 #7201
1987 560 SEC
1996 C180 A
1998 ML 320
1980 Stingray SV175 boat
http://suomi.mercedes-benz-clubs.com/

Bleeding with suspension hanging down does not help.

It looks that during few months "dry standing" either the 4 struts have started to leak, or 2 levelling valves have been defected or alternatively the oil pump has lost its output pressure.

Kari Pykäläinen

1971 6.3 #5581
1980 6.9 #7201
1987 560 SEC
1996 C180 A
1998 ML 320
1980 Stingray SV175 boat
http://suomi.mercedes-benz-clubs.com/

I have a theory now.

Perhaps the pump is not OK. If the pump can not supply pressure enough to overcome the sphere charging pressure the car will not rise. Earlier when the spheres were broken there was no counter pressure so a lower fluid pressure was enough to raise the car. But, one sphere was in tact; the rest 3 and center sphere were broken. The car was in correct level that time, when I got the car I mean.

I have to fabricate a pressure gauge with a valve that I can choke and see how much pressure the pump gives with a decent flow also.

Kari Pykäläinen

1971 6.3 #5581
1980 6.9 #7201
1987 560 SEC
1996 C180 A
1998 ML 320
1980 Stingray SV175 boat
http://suomi.mercedes-benz-clubs.com/

I built a test gauge with a needle valve and installed it directly on the pump outlet. The pressure went up to close 200 bar at idle, and there was still flow. So it looks the pump is in tact.



When running the motor I opened both normal drive position and higher position lines at the main valve and there was fluid coming out. So the fluid seems to go into the system but seems to stop at the levelling valves.

I doubt both the levelling valves would have failed when I lifted the car up by the body and axles being hanging.

I am running out of ideas now.

Kari Pykäläinen

1971 6.3 #5581
1980 6.9 #7201
1987 560 SEC
1996 C180 A
1998 ML 320
1980 Stingray SV175 boat
http://suomi.mercedes-benz-clubs.com/

I have been studying the W126 HPF shop manual and the attached pdf troubleshooting instructions.

So, the high position is disabled on my US specs car. The service position at the main valve does not drop the car, somewhere on the message board I read the car should drop. But it can not do that because the levelling valves hold the position in place, unless the car is "bounced", I need to test that this evening.

I was bouncing the front end and saw the levelling valve lever moves. Like it does at the back side when I bounce the car. And the levers/linkages look all right.

I opened the front bleed valve and a lots of bubbles came out. I bled the front for 3 hours and got approx 12 litres fluid that I recycled of course. The air bubbles come in intervals, first a burst of bubbles for 20 seconds, then it clears out. After revving for 5 seconmds the bubbles will appear again, and same continued for 3 hours.

The inlet hoses at the pump and the cooler have been replaced, the fittings are tight so it can not draw any air there. I just have to continue bleeding, I have to do it at rear also but I need to get a longer clear PVC hose so I can see if any air comes out.



Kari Pykäläinen

1971 6.3 #5581
1980 6.9 #7201
1987 560 SEC
1996 C180 A
1998 ML 320
1980 Stingray SV175 boat
http://suomi.mercedes-benz-clubs.com/

Just remove the small blocking sleeve from the end of the control cable at the main valve, and you should find that your high position is enabled as intended. Be sure to mark the cable for correct position before you release it, in order to facilitate correct replacement.





116.036.12.004946
116.036.12.006077
116.036.12.006588
109.018.12.000109

All right, it looks that on my car the high position has been enabled as there is no sleeve anymore.

Interesting observation today. I managed to get out the "golden filter" i.e. the small conical shaped sintered filter. It was dirty and I cleaned it. No help.

Then I decided to open the 22 mm hex bolt on top of the main valve, there was a spring and a ball under it. In the bore under the ball I found something soft, could not get it out. I disconnected the pump pressure hose and had an access to the same cavity. There was clearly something there that did not belong there. I used compressed air gun to clean the bores and I got out some tissue paper and some kind of sealant debris, like silicone paste.

But, cleaning the regulator part of the main valve did not help. I guess I need to dismantle the control part also, most likely the sealant has clogged the control part ports.

Similar sealant can be seen between the pump flange and engine block, somebody has worked on the pump earlier.

Kari Pykäläinen

1971 6.3 #5581
1980 6.9 #7201
1987 560 SEC
1996 C180 A
1998 ML 320
1980 Stingray SV175 boat
http://suomi.mercedes-benz-clubs.com/

I removed the main valve, took it apart into halves; the cast part and the aluminium part.

I checked the two allen head bolts/plugs at the bottom; the first one had a valve ball in the bore but the second did not have. The second one is the one I opened and replaced the crush washer due to leak. It looks the ball has dropped out even I was extra careful. Could be the ball was held in place by the fluid and it just got loose and dropped out when I was looking for a new crush washer.

I need to find out if I can get one dia 4 mm ball. I hope the both are same size. I'll try first a bearing shop, then a bicycle shop and finally a hydraulic shop if needed. I need anyhow a new o-ring between the valve halves.

Kari Pykäläinen

1971 6.3 #5581
1980 6.9 #7201
1987 560 SEC
1996 C180 A
1998 ML 320
1980 Stingray SV175 boat
http://suomi.mercedes-benz-clubs.com/

Now it works! Really it was the valve ball missing in the main valve. I installed a new ball and replaced the o-ring between valve halves. The car stood up quite fast at idle already.

Anyhow I have some loose ends to tidy up but I managed got temporary plates and insurance today so I hope to drive the car tomorrow.

Kari Pykäläinen

1971 6.3 #5581
1980 6.9 #7201
1987 560 SEC
1996 C180 A
1998 ML 320
1980 Stingray SV175 boat
http://suomi.mercedes-benz-clubs.com/

Well done! Looks like you are getting on top of owning a 6.9.

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126.037

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I was eager to do a test drive this evening, and managed to do it. Before test run I replaced the brake fluid reservoir bottom seals as they were bad and replaced the worn steering wheel with a nice one I got from ebay.

The car feels fantastic; suspension is comfortable and the car is very quiet inside. I can actually hear the clock ticking when cruising in town area.

The motor does not run extremely smoothly yet but I have not even checked the spark plugs - I will change those soon. The big block power plant pulls the car well and it looks the car has been tuned up to be run at low rpms. Plus the three-speed transmission gives its own flavour to driving.

Me like it!

Kari Pykäläinen

1971 6.3 #5581
1980 6.9 #7201
1987 560 SEC
1996 C180 A
1998 ML 320
1980 Stingray SV175 boat
http://suomi.mercedes-benz-clubs.com/