85' 300SD Rebuilt leaky power steering pump and now doesn't work! - PeachParts Mercedes-Benz Forum

superdiesel · #1 08-16-2006, 04:38 PM

Amidst a stressful week of replacing the radiator, oil lines and motor mounts, I decided to go ahead and rebuild my leaky power steering pump. Bad idea! Partially because it looks like Exxon Valdez under hood, due to a cut oil line. Anyway I removed the pump easily, but had a hard time getting the backing plate off the back of the pump even after removing the retainer clip. I got it off eventually and I took out all the internal mechanisms and replaced the energizer seal (thats what my dad the engineer called it because it has a spring on the rubber ring) on the front of the pump where the shaft comes out. After taking care to put it all back together, checking it to make sure it spun well, I put it back in the car with new ATF. Now I knew to bleed it via jacking up the front of the car with wheels off the ground, but now the PS DOESN'T WORK! I had PS prior to this, it was just leaking, now it is like there is no PS, even though with the wheels off the ground it was very easy to bring it from lock to lock. VERY frustrating. My question is am I missing something? Where did I go wrong? I am pretty sure I did not connect the wrong hoses (ie high pres. to low) to the PS pump. It is killing me after all the stuff I had to go through. Any help is greatly appreciated, as well as critisisms to the thread and what have you, as it is my first.
Also I am quoting someone here and I am sorry I did not copy their name down but they said it may not work after the reseal?

"I also found that Larry Bible said to replace the pump with one from the junkyard [about $125] when this happens [mistakenly put in ATF]. Also using the search I find that some pumps are fine after reseal and some never pump again. Since Larry himself hasn't answered I guess that means his own experience has been not good with replacing the seals. I guess I'm gonna find out.
Thanks everyone in advance, because I have been reading the posts for years and love all the great information"

(btw: it's easier to remove the bottom oil line on the oil cooler to filter housing to get the top oil line out, and replace top then bottom, I think)

kip Foss · #2 08-16-2006, 04:56 PM

I rebuilt the ps pump on my 107 and couldn't get pressure. Took it to the local hyd. place and they couldn't get pressure. Took it home, took out the relief valve, turned it around the opposite way, put it in, and, zippo, 1000 psi. I hooked the pump up to my 1/2 in. drill, hooked a 3k pressure guage to the discharge line, and it ran like a champ.

superdiesel · #3 08-16-2006, 06:08 PM

Quote:

Originally Posted by kip Foss

I rebuilt the ps pump on my 107 and couldn't get pressure. Took it to the local hyd. place and they couldn't get pressure. Took it home, took out the relief valve, turned it around the opposite way, put it in, and, zippo, 1000 psi. I hooked the pump up to my 1/2 in. drill, hooked a 3k pressure guage to the discharge line, and it ran like a champ.

Thanks! Which one is the relief valve? Is that part of the assembly inside?

kip Foss · #4 08-16-2006, 07:56 PM

If your pump is like mine, and I doubt that it is too far off, the relief valve is located on the right side behind the pulley. On mine there is a large nut, about 1 1/4 in. behind the pulley. When you take the nut off there is a spool (slide valve) and a spring. As I remember the spring comes out first and then the spool. Be sure to note which way the spool goes in. I kept putting my spool in backwards, which is why it would not come up to pressure.

There is not much to these pumps and as long as you put them back together as clean as possible and with spool in the right position I don't see any reason why it won't work. Get a 1,000 or 1,500k psi gauge and connect it to the discharge hose and see what you get for pressure. As I remember I had to make a fitting to go from the hose to the gauge. I'll check if I still have it around.

Stevo · #5 08-16-2006, 08:10 PM

Did you put all those little 'vains' back in just the same way they came out, in the same slots in the same position?

I rebuilt one once and I think that was the cause it never pumped again

Hit Man X · #6 08-16-2006, 08:45 PM

I had the same issue, I hate the 617s pump. I just started drivin it and then the power assist came back...

superdiesel · #7 08-16-2006, 11:58 PM

Quote:

Originally Posted by kip Foss

If your pump is like mine, and I doubt that it is too far off, the relief valve is located on the right side behind the pulley. On mine there is a large nut, about 1 1/4 in. behind the pulley. When you take the nut off there is a spool (slide valve) and a spring. As I remember the spring comes out first and then the spool. Be sure to note which way the spool goes in. I kept putting my spool in backwards, which is why it would not come up to pressure.

Here is the thing. I never removed or tampered with the relief valve... Is it possibly clogged or frozen open?

Quote:

Originally Posted by kip Foss

Did you put all those little 'vains' back in just the same way they came out, in the same slots in the same position?
I rebuilt one once and I think that was the cause it never pumped again

I did not mess with the vains either, as I did not take them off the main rotor. I am going to try to bleed it once more and take it apart to figure it out. Also is there any truth to not using the ATF in PS pump anymore?

Hit Man X · #8 08-17-2006, 01:25 AM

Yes, don't use ATF... causes leaks. The ATF today isn't the same from 20 years back...

DrLou · #9 12-17-2006, 02:42 PM

Haven't rebuilt mine yet, but I suspect those vanes in the rotor have to be oriented correctly; IE, with the rounded, machined edge outward, to face the oval-shaped 'pump chamber'. From the appearance of the machining on mine, I wouldn't think the pump would work correctly - if at all - if the more 'squared' edge of these vanes were oriented outward...

I'll have more experience with this in a day or so...
-------------------------------------------------
Update: this project is now done, and the power steering is better than it's ever been. One gotcha: I made the mistake, initially, of not fully compressing the three internal elements of the pump 'core': front plate, ovoid pump 'chamber' and the backing plate. Correct assembly can be tested by checking the back-and-forth play in the shaft; there should only be less than a 1/16th inch from the shaft-rotor play, and no more.

I had not compressed these parts fully, and the loading spring was not adequate to push them together once assembled. Result? No pump pressure! Easy to fix with a correct reassembly.

Some part numbers; hopefully this will help someone out there (this is all for a W126, an '83 300SD):

Pump details: ZahnradFabrik Friedrichshafen A.G. (Schwab. Gmund)
Mercedes #: 126 460 1480 type: 767 2900 446
Gasket Kit: A 000 586 84 46
(2 O rings, one Aluminum washer for pressure valve cover)
Front Shaft Seal: A 018 997 60 47
Filter: A 000 466 21 04

Lou