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...

superdiesel · #9 08-19-2006, 05:06 AM

So any last suggestions before I tear it all back out and start looking for trouble? Thanks for all the help so far.

Hit Man X · #10 08-19-2006, 05:57 AM

Take it back out if you feel, they're just a PITA. Like other have said, it's probably that pressure valve. I just drove mine for about 40mi @ 65mph and it started to work again...

superdiesel · #11 09-01-2006, 02:59 PM

So I had put tranny fluid in to run the PS pump after the rebuild, which was probably was a mistake. So I changed that to regular PS fluid, I also checked the relief valve, since I didn't take it out in the first place, it wasn't in wrong but I cleaned it, and re-bled the system one more time, only to no avail. So the only other conclusion that I came up with was that the rear spring on the back of the pump that holds on the backing plate, was bent to much after taking it off, which it was and I just installed it anyhow. Do you think this makes that much difference? Any way I have no choice as I'm being made to do this, and after that it is up for sale, sad to see her go but can't have her like this.

Stevo · #12 09-02-2006, 10:15 AM

superdiesel ???

Your selling your car because you cant fix the pump? A wrecking yard should be able to supply one.

Beastie · #13 09-02-2006, 03:59 PM

Superdiesel , Where is OC ( Ocean City Maryland ?). If the ar is the black one in your profile email me before you sell it. If it is not any details on the black car in the photo. It looks great !.
Alan

Beastie · #14 09-02-2006, 04:00 PM

Duh ! , Orange county CAli. Sorry. Still is it the car in the photo.
Alan

superdiesel · #15 09-05-2006, 01:43 AM

No, I wouldn't sell the car because the pump doesn't work, that would be silly. I will fix the pump and some other things before I sell the car, and it might have been premature for me to say that. It is NOT the black car in the profile, though that one was one of the coolest on google images. I will probably release info when time comes in the classifieds section.

Thanks