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Old 10-28-2013, 08:23 PM
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LandYaghtLover LandYaghtLover is offline
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Join Date: Jun 2010
Location: Green Bay, WI
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SLS pump rebuild - done

More or less an FYI thread for those doing this.

I tried to rebuild the SLS pump last winter (maybe two winters ago). I ran into an issue with the o-rings. I bought sizes in standard suggested here, I could not locate metric. ******** does not sell the kit anymore. Issue was the slightly increased thickness. This causes the cam to slide too far forward allowing the interface in back to grind against the pump casing. I took it all apart and put the old ones back in.

Been living with a leaking system since then.

Today I took another stab at it. I used the same sized o-rings, but needed to compensate for the cam being able to now move forward nearly 2mm. I had no way to shift the bushing in the front "cap" of the pump outwards (back). So I crated a "shim" using a large flat washer. I used my Dremel to increase the inside diameter for a tight fit over the cam. I then ground the leading edge to create a bevel for the pistons to move under. Without the bevel there may be a chance for the washer to slide down in front of a piston head and jam it all up. This worked great. But the washer was a tad too thick. When I put it back together, I could not move the pump by hand. To fix this I ground the bushing and even some of the casing off the inside front cover (see pic). Now when tightened up there was just a slight amount of play. You do want a little to prevent any binding as all the bolts are installed when putting it back in.

So far so good. Took her for a drive, revved things up a bit and now no leaks. I will park in a new spot at work in the morning to see if I can find a spot on the ground. I would leak about 1 quart every week or two.

Really the correct size of the three o-rings may prevent any issues. I also think my pump was very, very worn. The original o-rings were cracked and very flattened out. But if you rebuild yours, make sure the cam does not have too much play. Also, don't forget the banjo bolt gets TWO copper washers an each side of the hydraulic line. I forgot one on the first attempt and it leaked all over.
Attached Thumbnails
SLS pump rebuild - done-img_1633.jpg  
1991 560 SEL / 185k miles
1992 750il / 17k miles - project car
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