w124 sls pump question... - PeachParts Mercedes-Benz Forum

locry · #1 01-17-2009, 12:51 PM

grrrrrrr... so i developed a leak in the valve area... causing my 87 TD to sag about an inch from normal...
upon replacing the fluid... after driving home... i noticed the reservoir was empty... possibly damaging the pump.

I didn't hear any unusual noises from the pump during startup...idle..and the drive home...

anyway here's my dilemma... with fluid added... the rear refuses to rise even when manually operating the valve lever(disconnected of course)...
i checked the fluid level in the reservoir... level didn't change... so the "new" fluid wasn't sucked/pumped in the system... naturally no fluid was flowing from the return into the reservoir.

did i trash my pump?
i drove around 30km to try and self bleed the system... checked the reservoir level...still the same... (haven't tried manually operating the lever yet as it's alrady late)...

any audible signs if a pump is kaput? no steering issues btw... no weird sounds when turning the wheel...

Bob Weir · #2 01-17-2009, 07:03 PM

"a leak in the valve area"
I assume you mean the "controller"? Per parts vendors these controllers rarely fail. It's usually an incorrect fitting of hydraulic line. Same for PS/SLS pump in that they rarely fail.

The system is "self purging" of air, however, if you've done any any major R&R, the fittings must be attached correctly. You may have to purge at the controller. An extra liter of FEBI 2615 fluid may be needed to adequately purge the system. This is not PS fluid, you must use 2615.

PS I'm not a maniac, however, I've been down this road with my 94 wagon and it took a few bleeds to get it right.

locry · #3 01-17-2009, 08:28 PM

yes sir... i meant the controller... and you are correct about the fittings. sad to say... but that dang mechanic who worked on my car might have cross threaded one of the fittings. (2nd fitting from the bottom)

(the accumulators were just recently replaced)...
all was fine until i developed a super leak (first leak) which "sprayed" hydraulic fluid all over the driveway when i tested the system by loading the car... went back to the shop to have them fix the leak, which they said they did... contrary to my suggestion to fill up with hydro fluid... they said i still had fluid left...(i was sure A LOT was sprayed away...) (my fault for trusting them)... anyway
i drove like this for a couple of weeks... didn't have sagging issues... but when i loaded the car with 4 people at the back... the car sagged and didn't "rise"... that'
s when i realized i didn't have "enough" fluid to raise the struts... but had "just enough" to keep the car level when driving unloaded.( i assume i had enough because prior to having the accumulators fixed and having almost no fluid my car sagged waaaaay below normal...you asked me to measure from the wheel star to the fender lip in another thread, will have to re-measure

)

because i didn't have time to buy fluid to top up the system i continued driving like this... until, while parked at the office, i noticed a significant pool of hydraulic fluid on the ground... leak happened with the engine off, which is weird since there shouldn't have been any significant pressure in the system. i don't know if climbing around 7 floors of the carpark had anything to do with the leak...(this is the leak which the topic of this thread) this concerned me more since having just enough fluid and having it leak out meant i had waaaaay less fluid now.

btw... i bought 2 liters of fluid... i have just added 1 liter since the start of the ordeal to try and confirm where exactly the leak is... couldn't get the system to "drink" the added fluid...

thanks for the advise... i think i may have to manually bleed the system as per your recommendation. thanks again... will update the thread.

locry · #4 01-17-2009, 09:04 PM

height unloaded=13.5 inches from center of wheel star to fender lip

johnathan1 · #5 01-17-2009, 11:41 PM

Try bouncing the rear with the engine running...this seemed to help my SEL get the fluid flowing.

locry · #6 01-18-2009, 03:43 AM

thanks for the advise bro...
quick update: i loaded up the rear as best as i could and bled through the bleed nipple at the top of the controller valve... as expected fluid came out... not really sure how much air was expelled in the process... but the amount of fluid that was expelled wasn't much. (i did this with the engine off)... checked the fluid in the reservoir... no change. i then added fluid thinking that the reservoir level might need to be "higher" than the hoses of the tandem pump in order for the pump to get primed... started the engine and watched for the level in the reservoir to go down... still no change.

tried bouncing on the rear... which was now spongy... like bouncing on springs alone. no change in the fluid level... it's like the fluid isn't getting to the struts/system.

possible blockage?

johnathan1 · #7 01-18-2009, 03:58 AM

The engine needs to be running while bleeding...and bouncing.

locry · #8 01-18-2009, 04:32 AM

ok... i did the bouncing thing with the engine running... no change yet... still springy...
i've yet to bleed it with the engine running. thanks again...
will drive it tomorrow and hope it bleeds itself... any danger to the pump in doing so?

ds190 · #9 01-18-2009, 11:37 AM

When my tandem pump failed, it did not make noise, it just didn't pump hydraulic fluid. I tried to bleed the system at the bleed screw on the control valve, and nothing came out. I then disconnected the high pressure hose from the tandem pump at the connection on the right side of the engine, and no fluid came out with the engine running at fast idle. Bad pump- I bought a rebuilt one from MBpumps.com in Houston TX.

Also, be sure the low pressure feed hose from the reservoir to the pump has not aged so much that is is blocked off. I would remove it and check.

"leak happened with the engine off, which is weird since there shouldn't have been any significant pressure in the system." Not true- the hydraulic fluid stays pressurized even when the engine is off, which is why the rear end doesn't sag everytime you turn off the car, and why you saw leaked fluid under your car forced out by that pressure.

"will drive it tomorrow and hope it bleeds itself"- haven't the other posts pointed out that that won't happen?

There are many many threads here about SLS, proper bleeding, etc. Use the search feature above.

The 87 is a great diesel wagon- good luck

locry · #10 01-18-2009, 07:42 PM

thanks... and yikes about the pump failing...
to test if the pump is indeed "pumping"... which connections are which?
supply/return from the pump... supply/return from the struts...

as it is i've been working on the car in the garage... no lifts. i'm not venturing under the car so it's pretty safe. I could reach up to the bleed nipple and can see the connections on the valve via a mirror... couldn't trace where the lines go though...
thanks again

ds190 · #11 01-18-2009, 08:31 PM

I don't remember which connects where on the controller valve.

On my 103 engine, a high pressure rubber hose comes out of the tandem pump, goes under the front of the engine to the right side of the car, and near the expansion tank, connects to a metal line going back to the controller valve.

The easiest thing for you to confirm if the pump is working is to disconnect that hose at that metal line in the engine compartment, put the hose in an empty milk jug or so, start the engine and rev up to 2k rpm for just five seconds, and turn off. If the pump is pumping, there will be fluid in the jug.

No fluid in my jug, so rebuilt pump for me.

Go Ravens!

locry · #12 01-18-2009, 08:49 PM

that makes sense... ok.. will do that later tonight. left the car at home and brought my bike instead. doesn't have sls so i'm good to go.

http://www.peachparts.com/shopforum/vbpgimage.php?do=full&p=1695&d=1171457021
here she is in all her (former) glory...

Bio300TDTdriver · #13 01-18-2009, 09:53 PM

Quote:

Originally Posted by locry

thanks... and yikes about the pump failing...
to test if the pump is indeed "pumping"... which connections are which?
supply/return from the pump... supply/return from the struts...

as it is i've been working on the car in the garage... no lifts. i'm not venturing under the car so it's pretty safe. I could reach up to the bleed nipple and can see the connections on the valve via a mirror... couldn't trace where the lines go though...
thanks again

These are from the FSM

A. Oil drain plug: server for releasing pressure in the system for working on or testing the system.
T. Return duct to oil reservoir.
P. Duct from pressure oil pump.
S1 Pressure line level controler, spring actuator right. Also listed as pressure duct to suspension elements on another page.
S2 Pressure line level controler, spring actuator left. Not listed on the second page, but should be pressure duct to suspension elements as well.
One goes to the left and one to the right.

BTW, how many SLS threads do you have going? It makes it easier if all the information is contained in one thread.

Bob Weir · #14 01-18-2009, 10:11 PM

Controller connections. Re your pik from bottom left corner going clockwise:
P > from pump
T > to reservoir
S2 > to left accumulator
S1 > to right accumulator
A > bleed screw

Disconnect turnbuckle when adjusting level. Turnbuckle connects to last [outside] hole of controller's arm.

Ride height on mine after new rear accumulators and new front shocks is 15" at each wheel. I suspect rear is about 1/2" to high with engine off, but haven't had time to adjust. Others note height range 14 to 14-3/4"

locry · #15 01-19-2009, 12:55 AM

thanks for the measurements/connections sirs.

Sir bio... i have 2... but that other one was more ride height/spring related.

this is more "pump" specific... should have the 2 merged or something...

did separate threads so someone searching for pump problems can find info easier.

i hope