Author Topic: Power steering pump (Read 33338 times)

waqas · « **on:** June 25, 2009, 00:40:03 »

Well, I've barely just worked through my brake issues and now it's the steering's turn.

I noticed a little puddle under the front of the car and lo! My power steering pump seems to be leaking from the front seal. (I replaced all the hoses some months ago)

I have two questions:

Has anyone rebuilt these pumps using the available seal kits?
Is the little elbow feed hose available as a formed hose or is it only available as bulk hose? (it tends to kink slightly, since the turn is sharp)

Thanks for any guidance.

awolff280sl · « **Reply #1 on:** June 25, 2009, 01:50:04 »

Waqas, regarding the sharp bending of the small hose, I ran into the same problem. MB does not make a pre-formed hose for this application, and I couldn't find one that would be ok with PS fluid. I went with a "Unicoil" ( http://www.gates.com/europe/brochure.cfm?brochure=7718&location_id=11377 ). They're stainless and solve the problem. Several companies make the same type of thing.

waqas · « **Reply #2 on:** June 25, 2009, 04:53:56 »

Andy, thanks for the lead on that. Do you remember which size coil you ended up using for that elbow?

awolff280sl · « **Reply #3 on:** June 25, 2009, 12:02:46 »

I can't say for sure what size I used. I've also had to use them for the heater core bypass, so I've used a few different sizes depending upon the hose.
They sell these coils at many auto parts stores, so I took the hose with me to see if it fit.

waqas · « **Reply #4 on:** June 25, 2009, 14:59:18 »

Andy, thanks. I'll do the same.

waqas · « **Reply #5 on:** June 25, 2009, 15:02:06 »

Does anyone know if a used power steering pump can be tested for leaks somehow? (pressure test? what kind of pressure?)

Ack! it'll be a miracle if I can sort through everything before my drive to PUB!

wwheeler · « **Reply #6 on:** June 25, 2009, 19:49:47 »

Waqas,

I just bought the UNICOIL from a Napa parts house for the exact same problem. They are selected by the ID of the hose. I bought 5/8" and 3/4" because I couldn't remember which it was at the time. There should be a small portion of metal tube on the reservoir exposed so you can get a caliper in there to measure without having to take the hose off. I can look tonight and see what it is. I have heard really good things about this product.

menesesjesse · « **Reply #7 on:** June 26, 2009, 12:39:18 »

Wagas
I rebuilt my pump at the house. The seal kits are correct and are at most suppliers like Autohauz AZ. Took me about 1hr. Be sure to change all the seals to include the cap and filter. I know I will have to bleed the system once I get the car running. The pump internally is pretty straightforward. I will let you know if mine leaks but I feel confident it will not. As for the hose I went to NAPA and used their high pressure hydraulic line hose and it fit well. Hope this helps.
Jesse

waqas · « **Reply #8 on:** June 28, 2009, 18:08:26 »

Jesse, thanks for the info. Please let us know how the rebuilt pump performs once you get things running again.

Does anyone know if any of the bolts that hold the pump mount to the block enter any oil or water passages?
Since I'm taking things apart anyway, I thought I'd remove and repaint this metal mount before putting everything back together.

Dave Gallon · « **Reply #9 on:** June 28, 2009, 20:14:08 »

Use of the original hose and carefully fitting will eliminate any kinks. I have replaced this part several times over the years.

Repair of the pump is simple enough. This is a vane pump. Be sure to note the orientation of each individual vane (they will almost certainly fall out during disassembly) as they have a rounded edge which bears against the pump housing and a square edge which should be oriented inward. Aftermarket seal repair kits are fine but possibly vary in content. Insure you have the front radial seal and two O-rings. (Autohausaz and others offer a kit without the front radial seal, as well.) There is a special O-ring on the pressure regulator piston, part number 000 997 74 45, current suggested US list $7.50, suggested US wholesale $6.00. This is NOT a standard O-ring (not circular in cross section) and I highly recommend changing the part if you have the pump apart. Finally, if my memory serves, there should be an O-ring on the high-pressure hose where its fitting is screwed into the power steering pump, part number 000 997 72 45, suggested US list $2.00, suggested wholesale $1.60.

waqas · « **Reply #10 on:** June 28, 2009, 21:18:37 »

Dave, thanks for the great info.

Looks like my kit from AutohausAZ is labeled 000 586 31 46 and includes only two seals (see pics).

My parts book lists the gasket kit 000 586 01 46 as follows:

001 997 02 40
000 997 71 45
000 997 72 45

I assume these are the front radial seal and two O-rings?

Also, a pressure valve repair kit is listed as 000 586 00 46. If this kit includes the special O-ring on the pressure regulator piston that you mentioned, p/n 000 997 74 45, what else does it include?

In addition the book shows the same o-ring 000 997 72 45 being used for the fitting on the fluid supply side.

I'd like to compile a complete list of pump rebuild parts and add it to our technical manual. Any additional info is much appreciated!

Thanks

waqas · « **Reply #11 on:** June 28, 2009, 21:45:48 »

Got the pulley off the pump. Thought I'd share the tool I modified for this purpose.

The grooves around the pulley are too thin for most pullers available, so I bought a generic puller from Napa (see pic 1) and used my angle grinder to grind the puller teeth (see pic 2) until they easily fit into the pulley grooves (see pic 3).

Worked like a charm!

Dave Gallon · « **Reply #12 on:** June 28, 2009, 21:58:58 »

Most curious. If you go to the Autohausaz web site and check 000 586 31 46 (which is the correct part number for the repair kit) you will find the picture shows two O-rings as well as the front radial seal. There are definitely two O-rings at the parting surface between the pump housing and pump housing cover (front part of the pump).

001 997 02 40 is the radial seal ring
000 997 71 45 replaced by 000 997 01 45 is the small O-ring
000 997 72 45 is the large O-ring
(kit 000 586 01 46 has been replaced by 000 586 31 46)

Pressure relief valve kit 000 586 00 46 replaced by 000 586 60 46 contains the O-ring I mentioned, the valve piston, and a third part. Current suggested US list is $137.00, suggested wholesale is $110.00. In most cases the piston does not need to be replaced so the separate O-ring 000 997 74 45, while expensive for an O-ring, is the correct solution.

The repair parts as well as an exploded diagram of the pump should be in the Technical Manual. There is some excellent information on the pump in the R107 Workshop Manual from Mercedes

waqas · « **Reply #13 on:** June 28, 2009, 22:17:11 »

Ok, mystery solved: I went back and took out all the seals from the AutohausAZ kit and behold! the third o-ring was lodged inside the radial seal!

waqas · « **Reply #14 on:** June 29, 2009, 21:33:33 »

Removing the pulley revealed a trail of ATF flowing from the nose of the pump to the pump bracket.

Does anyone know why the pump bracket has one corner (rear left, w.r.t. the car) that is angled upwards?

Andres G · « **Reply #15 on:** July 02, 2009, 00:32:58 »

Hello Wagas,

Thanks for this post. I have run into the same exact issue and was waiting until after the July 4th holidays to get into it. I will follow the instructions posted here and hopefully I'll get mine solved.

Regards,
Andres G

menesesjesse · « **Reply #16 on:** July 02, 2009, 12:25:04 »

Wagas
I got my motor running yesterday and aside from filling the pump with new fluid I see no leaks. The rebuild went nicely and the parts are holding up well. I did restore the pump resivor also. There is a filter that does a good job and a seal on top of the lid. The total time was 2 hours for both parts. I used common tools for everything. Good luck.
Jesse

Ron · « **Reply #17 on:** July 06, 2009, 19:06:07 »

Hi Folks, in some other posts on this thread there were part numbers for the O rings in the power steering pump. Last week I ordered from the local dealer what I thought were the 3 rings for my pump, a straight shaft model. The big ring, that seals the two parts of the case, did not come in the order. Working with the parts man at the dealer, I have the correct numbers, I think. (I'll let you know when the big ring appears.)

000 997 74 45 is the "special" for the piston chamber (correct in old posts)
001 997 72 45 is for the large O ring (not mentioned in old posts)
000 997 72 45 is for the small O ring (listed as large O ring in old posts)

The last number showed up as the small O ring in my order. So using the second number, I reordered the large one.

I hope this helps. Ron

Dave Gallon · « **Reply #18 on:** July 06, 2009, 20:57:21 »

Let's try once more and get all these number straight. The pump has:

1) 000 586 31 46 (contains one large O-ring, one small O-ring, and the front seal). This is the basic PS pump rebuild kit. autohausaz has it for $8.63.
2) 000 997 74 45 this is the special O-ring for the pump pressure regulator. US list $7.50
3) 000 997 72 45 the small O-ring, get one more for use on the high pressure hose where it attaches to the pump. US list $2.00

The reservoir has:

1) 000 236 00 55 filter
2) 000 236 00 80 gasket (at lid)

Ron · « **Reply #19 on:** July 07, 2009, 04:14:10 »

Thanks Dave, I didn't have all the info when I ordered, so I already had the shaft seal. Therefore I wanted only the large O ring and I got the separate number.

Now, a perhaps final question on this thread: how tight should the key fit in the shaft? I have the key that came with the car with the incorrect pulley, and it is too thin for the keyway. (It had been glued in with J-B Weld.) I have the new key from M-B and it is a loose fit too, same as the key from the car. I haven't received my pulley yet, so I don't know what size slot will be there for the key, but shouldn't the key fit tight into the shaft keyway?

Ron

Benz Dr. · « **Reply #20 on:** July 07, 2009, 04:58:39 »

Yeah, it should fit tightly. The shaft is pretty hard on those pumps so it would seem odd that it would wear at all. The woodruf key is fairly soft and so is the pulley material; at least as compared to the shaft. The pulley will bend if you try and use a puller on it but it's still very strong.

I raise the car on my hoist and fill the canister. I keep turning the steering wheel left and right but mostly centered and it will eventually purge all the air out of the system. I used to bleed the sterring box but find that it's not needed once you use this method. You do have to keep the fluid level high enough so it won't suck in any air while you move the steering wheel. DON'T run the engine - that will defeat what you're trying to do. Wait until all the bubbles are gone which takes longer than you might think. Eventually you will get nothing but solid fluid bubbling up.
If you don't get all the air out the fluid will foam and start to blow out of the canister. The canister will go empty and start to suck in air which will make it really groan. Don't drive your car like this for very long. The pump can and will be damaged if it goes very dry. Carry a couple of bottles of ATF with you. It could save the day.

waqas · « **Reply #21 on:** July 07, 2009, 20:08:35 »

Ok, so I finally got around to dismantling the pump and I see how the large and small O-rings fit.

My questions:

(1) When I opened the pump a spring bounced out before I could see exactly how it was fitted. Where does it go? Is there supposed to be a second spring?

(2) How is the front seal removed and replaced?

(3) How do I access the O-ring in the pump pressure regulator?

Ron · « **Reply #22 on:** July 08, 2009, 03:23:13 »

Hi Waqas, here's what I found with my pump as per your questions:

>(1) When I opened the pump a spring bounced out before I could see exactly how it was fitted. Where does it go? Is there supposed to be a second spring?

The spring shown in photo 2 goes into the center dimple in the plate in photo 4. The pump is then put back together with the rotor, vanes and cage stuff in one hand, and the cavity, dimple and spring in the other hand. The second spring is larger and in the regulator, please see below.

>(2) How is the front seal removed and replaced?

I used an awl and just went under the lip of the old seal prying it out. Don't scratch the shaft with the awl. I then tapped in the new one.

(3) How do I access the O-ring in the pump pressure regulator?

In photo 4, you can see a small protrusion in the casting below the number plate. It looks like there's a black plastic plug there. Mine did not have that, so I'm not sure what that is, but you can barely see the roll pin that is to be punched out. That releases a small piston with the special O ring, followed by the regulator piston, then a larger spring. Careful, once that roll pin is out of the first hole and the opening, that stuff all comes springing out!

Ron

waqas · « **Reply #23 on:** July 08, 2009, 03:29:59 »

Ron, thanks for the answers.

Quote from: Ron on July 08, 2009, 03:23:13

In photo 4, you can see a small protrusion in the casting below the number plate. It looks like there's a black plastic plug there. Mine did not have that, so I'm not sure what that is, but you can barely see the roll pin that is to be punched out.

That's a black plastic plug I inserted myself. I have a habit of plugging things as soon as I disconnect them. (prevent spillages and, conversely, dirt from getting inside).

Is this the pin you're referring to? (see pic)

Regarding the front seal, is it recommended to use any kind of preparation and/or sealant when installing the new one?

Ron · « **Reply #24 on:** July 08, 2009, 04:04:28 »

Hi Waqas, yes, that is the pin. I used a drift to knock it out.

As to the seal, I don't know if there's anything special about it as to installation. It is double lipped, so I put grease in the cavity, and placed down over the shaft. Then i used a small hammer to tap it in, keeping is square with the housing hole as it went down. The outside of the edge of the seal was plastic? coated, so I did not use sealer on that, where I normally would on a metal ringed seal.

Now, I have a question in return. That special O ring is in there. Mine old one looks like a regular O ring, but with the outside side flat. That is, it has a "D" cross section, with the flat of the "D" facing out. The new O ring looks like a regular O ring to me, it is round in cross section. Am I missing something? Maybe M-B didn't send the correct one? What is so special about the new O ring? I've put the new O ring in the pump regulator, and it was a good fit. But now I'm thinking I should order that O ring again and replace again. I don't want to have to pull this apart after starting my car for the first time! (I've had it almost a year, and have never driven it, nor any other SL.)

Ron

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Author Topic: Power steering pump (Read 33338 times)