Then it has no purpose yet it is there. There is no flow throuh it to act as a heat sink (like a power steering cooler), not enough volume to be a reservoir... it appears to be a simple extension hose that leads nowhere... It has to be some kind of pressure relieve damper.

Unless somebody has better ideas?

I think it there to dampen spikes at the pump. Its the result of two Germen engineers compromising under pressure (Get It)

I received my Star Diagnostics Factory DVD today and it says that the hose is indeed a "Pulsation Damper" (Special Protection Version). This DVD is amazing. Well worth the $85 I paid. If anybody needs to know how to do something "By The Book" let me know and I will look it up. The procedure to remove and replace the hose is extensive but very doable. I will probably start tomorrow after work and get-er-done.

Thanks for all the replies.

Take care,

Brian

\

Brian,
I didn't know about any CD ? Can I get one ?
Thanks

Christeen442, I have to agree. If I'm not mistaken the electro-magnetic systems have been out there foir quite a while and have been proven on the road and track. Much less hardware involved and much easier to operate and diagnose than these super exotic hydraulic systems. see this:

http://youtu.be/IQ1eKddstxM

Pretty cool stuff.

I got mine from here: http://auto-repair-manuals.com/

I am going to go back and get the DVD for my R500 today. This DVD is really great!

Can somebody please explain to me exactly how allowing air into the tandem pump will cause it to grenade as many have stated? I certainly don't understand how something as compressable as air could cause a device that is designed to handle fluid pressures in the 3000psi range to get damaged. I understand the dangers of running the pump dry thus causing bearing and piston damage, but air? That makes no sense to me.

Oh and by the way, I don't agree with Mercedes calling this hose a damper. Much more like a catestrophic pressure relief valve. Especially judging by the fact the dealer told me he replaces so many of these that he must carry 2 in stock at all times. IMHO

no lubrication or cooling. once it cavitates it runs dry and self destructs.

same applies to fuel pumps

lol at "catastrophic pressure relieve valve"

Now I get the running dry part then if you continue to run the pump it will "eventually" give up the ghost. However if you read what some are writing on this forum the second air hits the pump, "BOOM!!!!!" it's a goner.

From my understanding and reading into the replacement procedure for the ABC pump, if the pump starts to suck air may lead to loss of suction (pressure). If this happens, the pump stops circulating the fluid and will run dry even though the reservoir may have fluid in it.

Upon replacement of the pump, you need to fill the reservoir and then pressurize it with a air hose to get the pump to start sucking and recirculating the fluid.

once you hit air - you facilitate cavitation which drops efficiency of the propeller and the pump might never see more fluid (has no power to suck in) so it runs dry.

so yes- air "bubble", but it sticks in the pump and never leaves...

for that same reason when replacing pump you need to prime it as it does not generate enough vacuum when running dry to draw fluid on its own.

You may want to check your accumulators.

Yes, I agree. In fact I'm pretty sure that I have a faulty accumulator due to the droning sound I started getting a few months back. Thanks,

usually the tandem pump is the source of similar sounds. the belt is the other.

or a pulley. they are known to fail at a very high rate.

Does any body know how to do a proper tandem pump exchange. I bought another used tandem pump to replace the old one that was leaking and now i took the part out but need to know the proper procedure to putting the other one in. thanks in advance

Install in reverse of what you did to remove the pump.

As far as the proper procedure goes, you will need a shop computer (DAS) to Rodeo and verify pressures as well as an air compressor to to prime/pressurize the reservoir if you want to follow Mercedes service exact steps.

I can print you out the procedure from WIS (Workshop Information System) when I get home. Alternately, you can search for a user names Oxygen. He posted the exact steps with pictures in the past.

Proper instructions for me to do it in my garage lol. But also please sent me the other way too. Thanks Preciate it

Is a flash or "rodeo" necessary what happens if u don't do it?

Absolutely as this is how the system self- bleeds. Otherwise you risk air pockets and if the tandem pump hits one- you are back to square one.

This is an update that I may have posted elsewhere. I have been driving the car daily for a month or more and everything is perfect. I sent the old shock back to Arnott (they provided a prepaid UPS label) and within a few days I received my $200 credit to my Visa card for the deposit I paid for the core.

If you do find that the system is in need of fluid and there is no leak, the issue at hand is that the accumulator/accumulator's are losing Nitrogen and being replaced with fluid. Once the fluid replaces all of the Nitrogen then you will have to replace them. I recommend replacing all of them at once. Do not replace one at a time as they will follow suit of failure. Like I tell everyone. Do the BOUNCE TEST it is 100% on the money. If you go the front of the car and try and bounce the car up and down and it bounces then your accumulators is weak. Do the same to the rear. If the car doesn't move then your system is OK but if it keeps loosing fluid it will eventually become like a bouncing old Cadillac that feels like it need shocks. If you see a leak. Stop the car and turn it off. Call a tow truck and have it repaired before you pump out all the fluid and then you run the chance of burning up the pump as well as the intermediate pump. Then you will wish you hadn't waited to fix that pesky little drip.

How many accumulators are on the 2004 S600? I have seen many different diagrams that show other devices they call fluid reservoirs and even air chambers.

With regard to the "bounciness" problems noted above and replacing accumulators to correct it, how many and where are they located?

Thanks,

4 units. 3 different part #'s

(1) Pulsation Dampener
(1) Pressure Relief
(2) Accumulators

My 2004 SL55 ABC pump was leaking fluid so I purchased a rebuild pump from eBay. After my mechanic installed there's still no pressure and the ABC warning msg stays on. After tried a few things including change the filter it still no working. So I asked a Mercedes mechanic to look at it and he confirmed the pump is no good. So I got another pump from the supplier and my mechanic put it on again but still there's no pressure. I notice the ABC warning come up right after I start up the car when the engine is hot. But after I parked overnight the warning pop up after I drive the car for 5 mind. So there's a difference between cold and hot engine. Any idea what's the problem? Or simply supplier with bad quality. Thankd