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  #1  
Old 03-10-2010, 06:32 PM
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1992 300TE SLS Troubleshooting

First I like to thank all of you that provide very useful info to this forum. At many occasions your posts have been of a great help to me. I only register today for the first time.
Here is my problem:
The 300TE doesn’t self adjust. Its low in the back, but it doesn’t seem to be all the way down. Maybe the springs are holding it up a little. Putting some weight in the car brings it lower. I don’t know if the problem is from the pump (124-460-15-80) or the self leveling valve (124-320-00-58).
The pump is working because with the engine idling, when I open the bleeder at the self-leveling valve, fluid is coming out, but there is no fluid going to the return line at the tank. There is fluid in the holding tank and it looks clean. I have read in previous posts that the fluid circulates all the time, except for when the level is in fill position, which makes sense. So if the fluid doesn’t return to the tank, does it mean that the pump is not pumping enough? Do pumps behave this way? I’m trying to avoid change it, and then find out it was an internal leak at the self-leveling valve or something else minor that I don’t know.

I did change the leveling valve with one from a junkyard, but it looks as my original was in better condition (tighter at the level) than this one. When I removed the supply line to the valve there was pressure in the line. Also the car was slightly higher with the old valve. It could be that the old valve was holding some pressure from the check valve before was removed.

I did operate the lever manually but the height didn’t change. So if the lever is in fill position and there is an internal leak at the valve, theoretically, would the fluid return to the tank as if it was in the neutral position?

I have read all a can read, but I’m lacking experience. I hope someone can help me diagnose this problem.

Thank you,
Michael

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  #2  
Old 03-10-2010, 08:47 PM
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check the pump

Sadly for me and my checkbook, I've done everything on my 300TE SLS except replace the valve. System works perfectly knock on wood.

Just because foamy fluidy stuff is coming out the bleed valve, don't assume the pump is working. Nothing's returning to the tank right?

I finally figured out that to check the pump, you must disconnect the high pressure supply hose where it junctions the metal line that goes to the leveling valve. That connection is under the hood, passenger side, near the coolant expansion tank. Disconnect it carefully.

Fill the hydraulic fluid reservoir with fluid, place the supply hose in a bucket, turn on the engine, and run it up to about 2500 rpm. Watch the fluid level.

If nothing's coming out the supply hose except foamy junk, pump is bad.

Also, the hose from the reservoir to the pump can disintegrate over time and close up. That's low pressure into the pump, so it doesn't take much to block that hose.

However, if level of hydraulic fluid in the reservoir is clearly lowering and the fluid going into the bucket is not foamy but clear normal colored fluid, pump OK.
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  #3  
Old 03-10-2010, 09:06 PM
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exact same thing happened to me once... no height change even after manually moving the lever up/down... foamy fluid did come out at the bleeder valve, but not under high pressure... it just leaked, which told me that the pump was either NOT pumping or there was air in the system.

Long story short... I eventually couldn't bleed the system AT the valve so i bled it AT the pump... there's a banjo bolt at the tandem pump, i loosened it up and after a few seconds fluid squirted out under pressure...

tightened up everything... now i can move the car up/down by moving the lever...

if you're unsuccessful bleeding at the valve, bleed at the pump.
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  #4  
Old 03-11-2010, 06:47 AM
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That’s good info! I will check it out and post the outcome.

Thank you
Michael
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  #5  
Old 03-11-2010, 06:27 PM
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Bad Pump

Well, I went strait to the high-pressure output the banjo bolt; it was easy with a 17mm open-end wrench. Not a drop of fluid coming out. I even removed the supply from the tank to make sure wasn’t plugged.

Next: new pump, $780.00 new from the dealer, some time next week.

Thank you ds190 and locry for the troubleshooting tips, very useful.

Michael
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  #6  
Old 03-11-2010, 06:45 PM
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I'm following this thread as I think my pump might be toast too...

My rear end does not self level, but it does not bounce and is firm (which I heard means the accumulators are OK)
Fluid is good and no leaks. So what else could it be? Sound like the pump to you guys too?
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  #7  
Old 03-11-2010, 08:09 PM
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ps2cho, using a 17mm wrench, loosen the banjo bolt while the car is running, as locry suggested to me. If there is pressure on the output, fluid should squirt out.

If your car has the same pump as mine (power steering and hydraulic in the same pump 124-460-15-80), the hydraulic section (banjo bolt) is toward the front of the pump, closer to the belt. Removing the air intake hose allows plenty of room to use the wrench to crack the bolt open.

I will post SLS basic function, which explains how the system works at another time for all with the SLS problems, but what locry and ds190 suggested, should tell you if the pump is bad.

Good luck
Michael
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  #8  
Old 03-12-2010, 02:06 AM
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Quote:
Originally Posted by michaelf View Post
ps2cho, using a 17mm wrench, loosen the banjo bolt while the car is running, as locry suggested to me. If there is pressure on the output, fluid should squirt out.

If your car has the same pump as mine (power steering and hydraulic in the same pump 124-460-15-80), the hydraulic section (banjo bolt) is toward the front of the pump, closer to the belt. Removing the air intake hose allows plenty of room to use the wrench to crack the bolt open.

I will post SLS basic function, which explains how the system works at another time for all with the SLS problems, but what locry and ds190 suggested, should tell you if the pump is bad.

Good luck
Michael
Thanks. Does the rear end need to be loaded during this test?
And yes my pump should be the same as yours. Sounds easy to try...I'll give it a shot as soon as my transmission is back in!
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  #9  
Old 03-12-2010, 03:35 AM
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if it's not pumping as soon as you loosen the banjo bolt try this... (just theorizing at this point)... kill the engine, fill the reservoir to the brim, or at least fill it as high as the pump... the pump may just need priming... if there is air at the pump fluid has to reach the vanes first... try priming before replacing the pump...

i know for a fact i ran mine dry for quite a while... it still works...
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86 230E (-->300D) sold
87 300D (-->300TD) sold
68 250S w/ a 615 and manual tranny (RIP)
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  #10  
Old 03-12-2010, 09:44 AM
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The No-Drip-Fluid Mystery

Quote:
Originally Posted by ps2cho View Post
Thanks. Does the rear end need to be loaded during this test?
No. The pump is running all the time.

Locry, it was strange that no fluid at all came out of the output, even when I was able to see the hole in the banjo bolt with 3000RPM. That didn't seem normal. I expected to see at least some drip coming out. Then I removed supply and output hoses and blew air through. Put it back, still no fluid. Two days earlier, when I changed the leveling valve, there was some pressure at the bleeder. The fluid in the tank is at min but never empty. Now you have me wondering if there wasn’t enough gravity all along, and when I changed the valve whatever fluid was in the pump show by the bleeder. I will fill it to max and see. If still no fluid, I will try to apply some air pressure at the tank also, somehow. Is a very long shot, but if this is the problem, you will save me over $1000.00, making you my hero.

Michael
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  #11  
Old 03-12-2010, 11:00 AM
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rebuilt tandem pump

I bought a rebuilt tandem pump from MBpumps in Las Vegas. Small outfit, I think I sent him a check first, installed the rebuid, and returned my core.

(702) 481-1312. About $200 in 2008.

And, if you have to supply air pressure to the low pressure supply input, it would seem effective to put air into the fabric covered low pressure supply hose. Again, this hose can clog.

Last edited by ds190; 03-12-2010 at 11:07 AM.
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  #12  
Old 03-12-2010, 04:54 PM
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The mystery of No-Drip

Quote:
Originally Posted by ds190 View Post
(702) 481-1312. About $200 in 2008.
Ds190, I called the nubmer and an answering mashine said it was a clinic. The number is correct, according to the yellow pages.
Quote:
Originally Posted by ds190 View Post
And, if you have to supply air pressure to the low pressure supply input, it would seem effective to put air into the fabric covered low pressure supply hose. Again, this hose can clog.
OK, I clear the tank and the low pressure hose was not plugged. The old fluid was black as someone used the wrong oil and at the bottom of the tank there was black mud. Now I'm hopeful. Put new fluid from Mercedes and anxious waiting to see a drip. Still no drip with the engine on or off.
The brainstorming continues:
With the new fluid in the tank, I removed the return tubing at the cap of the tank and using a tire air pump applied air pressure to the tank. I can see the tank is holding the pressure. Still no drip from the banjo bolt.

So the Hydraulic fluid doesn't get to the vanes of the pump like something is blocking it. Is this normal for a bad pump? From what I know if the pump goes bad, either leaks, or doesn't build enough pressure. Any ideas?

I have this car since 2005 and the SLS only worked once when I first bought it. At the time, I loaded the car with heavy boxes from IKEA, not knowing anything about SLS, and to my surprise when I started the car it levered by its self. I was so amazed with that feature, that when I discover it didn't work anymore, I brought it to the dealer to fix it. They kept on telling me there was nothing wrong with the car. So I gave up until recently when I found the used leveling valve in the junkyard. I knew that by touching it, there was a possibility it could empty my pockets. So this isn't a new problem, but since I changed the leveling valve the other day, the rear is a little lower and now doesn't have an acceptable or safe ride and I also feel the bumps of the road. Leaving it like this isn't an option anymore.

Michael
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1992 300TE 188,000 miles
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  #13  
Old 03-12-2010, 05:57 PM
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time for new tandem pump

If I understand, you cleaned out the reservoir, you removed the fabric covered hose from tank to pump and looked through it to know for sure it is not blocked, you also looked at the nipple on the pump that hose connects to to be sure no crud is obstructing that opening, you assembled and filled with fresh Febi or MB hydraulic fluid, you opened that banjo bolt per locry or disconnected high pressure supply hose per me, you ran the engine for 1-2 minutes at about 2500 rpm, and no hydraulic fluid comes out of the pump......we must say that pump is no more, it's deceased, it's expired.

The very last thing I tried before buying a new pump was, on the bench, drip/pour fluid into the outlet side while spinning the pump counterclockwise to see if any junk can be forced out. Air won't do it, use fluid.

Bummer that MBpumps is also no more- I hope I wasn't his last customer

Used pump from Potomac German Auto Frederick MD?
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  #14  
Old 03-12-2010, 09:01 PM
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Yes it is

Quote:
Originally Posted by ds190 View Post
......we must say that pump is no more, it's deceased, it's expired.
Looks like, but was worth the try. All the ideas and brainstorming in this conversation would probably benefit someone in the future.

Quote:
Originally Posted by ds190 View Post
The very last thing I tried before buying a new pump was, on the bench, drip/pour fluid into the outlet side while spinning the pump counterclockwise to see if any junk can be forced out. Air won't do it, use fluid.
I wish I had room for a small shop and a driveway big enough to work on a car without interfering with everyday life. If I did, I would have made some type of lift, easy for me since I am an iron worker. Here in New York City room is limited so I'm forced to depend on my mechanic. Anyway, thank you guys for all your help and the quick responses. Great group in this forum!
Quote:
Originally Posted by ds190 View Post
Used pump from Potomac German Auto Frederick MD?
A used pump is a good idea for someone that is willing to do the work by him/her self. If the used pump is no good (very possible since the cars are very old) and have to pay labor twice it would cost almost as much as a new one, and I would be stuck with an old one.

If I come up with a way to back pressure fluid through the pump without removing it from the car, I may try. Ds190, I think blockage is possibly the reason, since I found so much mud in the bottom of the tank when I cleaned it, but a new pump is unavoidable at this point.

Thanks,
Michael
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1992 300TE 188,000 miles
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  #15  
Old 03-13-2010, 01:14 PM
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Remanufactured Pump

Ds190, I found Maval Manufactures in OH, that have refub pumps, a possible replacement to MBpumps. Here is their website: http://www.mavalgear.com/
I will call them Monday, but it seems they sell via Unisteer. Here is the Unisteet website for the Maval refubs:
http://www.unisteer.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=UNISTEER&Category_Code=REMANUFACTURED
The price for the 300TE pump is $207.41 + $50.00 refundable for the core. I don't know shipping yet but sounds like a good deal.
Maval seems to have a large inventory on Power Steering, Racks and Gearboxes and the say their refubs come with LIFETIME WARRANTY. Looks like a good place to bookmark.

Michael

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