230SL Injection Pump Oil Line Check Valve Ball

[DaveinOC]

I read with great interest the thread on the oil line for the 230SL here:
https://www.sl113.org/forums/index.php?topic=26411
I'm in the process of updating a lot of the car due to sending the heater core out for repair. If you haven't done this you ha e to dismantle most of the dash, so while I sent the heater core out it seemed like a good time to replace all the hoses. Of course to do this with A/C means taking off a good share of the engine accessories, so that seemed like a good time to send the Injection Pump and injectors out to Jerry Fairchild. While cleaning the oil line and check vale I managed to misplace the check ball. If I don't find it a new check valve is about $1k from MB, so I'd like to avoid that. It appears the check ball is somewhere between 5mm and 6mm in diameter. Does anyone know the exact size of this? McMaster-Carr sells metric ball bearings that should work fine if I have the correct size.

[Benz Dr.]

I don't think it's a ball and it's more like a check valve similar to the one on the cold start valve. MB wants 1K for that little part???!!!!

[DaveinOC]

The part number I found from the EPC is 000-074-02-84, retail of $1,070.00 US. Seems a bit much. When I took it apart there was a spring in the pump end fitting, a rod with two different diameter ends, one of which fits the ID of the spring, and what for all appearances was a steel ball bearing in the housing which mates to a concave machined surface on the orifice/housing piece  I was certain it was secured and not in a magnetic parts holder, but there must have been one of our famous southern California earthquakes, and it disappeared into the hidden place where the Jesus clips go to hide. The hole appears to be 6mm so if no one has one they can measure and tell me for sure I'll try 6, 5.5, and 5mm balls and see which seems best. (McMaster-Carr sells them in lots of 100 for about $6...) With some residual oil on it I had to smack it on the workbench to get it out so I'm betting 6 or 5.5mm. (You don't happen to have one lying around you can mic do you  Dr?)

OT but I also investigated why the PS pump adjuster stud seems so short it didn't have any nuts on it and found it was snapped off sometime in the past. The adjuster stud/washer piece is not as bad at $139.00 but I think I can weld a new stud on the washer part for a lot less than that.

[wwheeler]

It is not a ball in the valve but rather a brass piece with a machined seat (maybe 45*). It is the exact same seat type as on the CSV because I have taken both apart. I never took a picture of just that and is a very special piece. I will try to describe: It is about 10mm long, has three "vanes" along the sides that act as guides as this piece slides up and down in the bore. It has a seat machined on it that matches the seat in the valve body. Sort of reminds me of a torpedo. That is the piece you are after, not a ball bearing.

You can't buy this separate because it is "fit" to the valve body and only sold as a unit. If you found a used "torpedo", it would probably leak due to the seats not mating perfectly. You could possibly lap it to the old seat, not sure. Best bet is to find a used assembly. Fairchild may have some.   

[DaveinOC]

Thank you for the detailed description WWheeler. I had just disassembled the valve to clean it when I was urgently called away and I guess I mistook the vane type plunger for a check ball and thought it was missing when I returned. Do I have all the parts as you described? It sure sounds like I didn't lose anything except part of my senses! Here is what I have:

[wwheeler]

Looks like you have everything to me. You test the seat seal by using a very low PSI source. If I leaks, it can be lapped to restore the seal. You can breathe easier now!