Author Topic: power steering pump rebuild  (Read 6039 times)

ptooner

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power steering pump rebuild
« on: April 21, 2013, 22:02:41 »
After putting up with the leak for years, I embarked on a power steering pump rebuild a few weeks back.  It looked like a Saturday job and might possibly have been that way for someone.  I discovered with the battery removed for visibility and the car on jackstands I could reach the three necessary bolts as well as the adjuster from below.  The first step is to back off the two 10mm nuts on the adjuster and then loosen the two 17mm bolts and the one 14mm bolt at the rear of the pump.  The problem came in trying to get the pulley off.  As I recall, the pulley itself required a 7/8 inch (or possibly one inch?) wrench to hold it steady while loosening the 19mm nut that holds it on.  I can assure you that the 19 mm nut served no real purpose because that pulley wasn't going to come off.  I'm sure someone will manage to get off the pulley with some special tool but with way over 50 years experience I couldn't do it.  I didn't realize that the pulley was actually cast iron until the first piece broke off.  Anyway, if you attempt this job yourself I will tell you that the only difficult part is getting that damned pulley off.  I will also tell you that they are hard to find replacements for.  Assuming you finally get the pulley off, and you must do so in order to remove the mounting bolts, you then simply remove the hoses and the three bolts.  Try not to lose the parts of the adjuster in the process.  Once off the pump comes across very simply and needs about $6 worth of o-rings to rebuild.  Once you have it cleaned, restored and re-painted, start your search for the pulley.  It is availble on special order from Germany for about $250 from MB classic parts.  Once you get in the new pulley, re-install the pump leaving the three mounting bolts loosely installed and the nuts backed way off on the adjuster.  Next attempt to re-install the belt at which time you will find that there is no way to get enough slack.  Pull it over the crankshaft pulley and halfway around the pump pulley in the direction of rotation.  Then bump the starter and the belt will jump back on.  Then consult your parts bag for you fluid and discover the new belt still in the bag.  Next, remove the old belt by the same halfway loose and bump starter method.  At this point it's a good idea to get yourself a cold one.  Next install the new belt using the starter trick again.  Pull the adjuster up to about 1/2 inch slack on the belt and tighten all three bolts.  Refill system and you are all done. 

Only time will tell if I have actually stopped the leak, but the car drives properly again.

Lesson learned:  Remove the radiator and the condenser before starting so you can get a puller on the pulley.

Gerry

ja17

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Re: power steering pump rebuild
« Reply #1 on: April 22, 2013, 02:03:31 »
Hello Gerry,

Sorry to hear of your difficulties. The earliest version pulleys are cast and they have a straight shaft to mount on.  These are the most difficult to remove. The later versions had a tappered shaft and were stamped steel.  Sorry we did not know of your dilemma, many of us are kicking good used pulleys around in our back yards.
« Last Edit: April 22, 2013, 02:12:39 by ja17 »
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

w113dude

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Re: power steering pump rebuild
« Reply #2 on: April 23, 2013, 10:47:53 »
Gerry,

I also did a similar project lately, i can tell you even with the front radiator out of the way those pump pulleys are impossible to get off, you have to take the pump out with the holding bracket then use a press to get the pulley off. It looks like a very simple job but boy what a ^%$# to get to.

ja17

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Re: power steering pump rebuild
« Reply #3 on: April 23, 2013, 12:32:32 »
There is a special tool (puller) that fits in the groove near the nut, to remove the pulley.  Some generic pullers may work also.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

mbzse

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Re: power steering pump rebuild
« Reply #4 on: April 23, 2013, 14:01:48 »
Quote from: ja17
There is a special tool (puller) that fits in the groove near the nut, to remove the pulley
See picture attached. If you work on the rim of the pulley, you may deform and ruin the part.
Gerry, I do not see any mention of you exchanging the shaft lip seal of the pump. This is where these pumps like to start to leak

Here is a useful previous thread on the subject, by waqas and others http://www.sl113.org/forums/index.php?topic=10980.25
/Hans in Sweden
« Last Edit: April 23, 2013, 14:17:02 by mbzse »
/Hans S

49er

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Re: power steering pump rebuild
« Reply #5 on: April 23, 2013, 15:02:58 »
 Interesting topic and very timely. Made an appointment with my mechanic, Ernie,  last week to bring the car in today for it's annual checkup and I mentioned that I noticed a few drops of ATF on the ground coming from the PS pump. Wife and I took the car out for a pleasant 100 mile drive this past Sunday and when we got home the few drops had increased to "many" drops. I checked the reservoir and it was about 1/2 full (full before our trip) so it looks like a pump rebuild will be on "To Do" list for Ernie. Timing is everything:-)

John
1969 280SL 003820
Un Restored, All Original, including the paint
Original Owner, Purchased September 18, 1968
4 speed manual, PS. 77217 miles
7280 miles since awoken from her 20+ yr "nap" in 2010

w113dude

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Re: power steering pump rebuild
« Reply #6 on: April 23, 2013, 18:50:27 »
So is it necessary to change the shaft as well as a rebuild process?

wwheeler

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Re: power steering pump rebuild
« Reply #7 on: April 23, 2013, 20:01:32 »
I bought a power steering puller at Napa that worked for this. I just had to grind the jaws a bit. Wasn't expensive and avoided messing up the pulley. 
Wallace
Texas
'68 280SE W111 coupe
'60 220SE W128 coupe
'70 Plymouth Roadrunner 440+6

ja17

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Re: power steering pump rebuild
« Reply #8 on: April 23, 2013, 20:05:10 »
No shaft needed Shaun,  just the "shaft seal".
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback