PeachParts Mercedes-Benz Forum - View Single Post

stevebfl · #3 04-10-2006, 07:09 PM

I wish I had the answer, as I have faced the problem scores of times.

The scores of times I'm talking about were times where we got the car up with no other parts. The scores of times don't include the few times we have actually had parts fix the situation.

The first problem I have seen is an airpocket between the reservoir and the pump. I take the line from the pump to the valve off and place it into the reservoir and runn the motor 2000rpms. If this picks the fluid up you won't be able to cap the hose with your finger. If you can't get this state then I have applied airpressure sealled loosely with a shop rag into the reservoir to force fluid into the inlet of the pump.

If the pumps is pushing fluid then the worse case I've seen goes something like this; The pump pumps so slowly that one can place a finger over the outlet hose. One should NOT be able to stop flow. Flow is small but pressure will build. If one places a gauge directly on the line it will peg about instantly and blow up. My gauge goes to 5000psi and it takes a couple seconds, then it better be shut off.

The issue I have always felt was that the flow to the return is too great to get pressure started. I have figured that there is a valve that is not seating unless the flow is huge. I have always solved the problem by a sneeky technique. The problem is that it isn't very easy to explain. The issue is that there is a passage from the height valve block to the regulating valve block that I block (fluid return passage). It is in the lower forward quadrant. I loosen the bolts holding the two valve together and slide a feeler gauge in till I cover the hole. Then I start the car run it till it starts to rise and shut it off and pull the feeler gauge and retighten the valves. I'm not sure I would suggest trying this. If you got a copy of the hydraulic schematic, you will see that the fluid enters the regulating valve from the pump, exits the regulating valve and fills the central reservoir, it then goes back to the height adjusting valve which distributes the flow to the system, the rest returns throw the circuit I'm blocking through the regulator to the reservoir. There is no need to flow through that circuit that is blocked till the car ghas raised.

If none of that works I'm guessing you missed something.