Troubles changing the primer pump on a w115 240d
 

So I'm attempting to change the primer pump on my not-yet-on-the-road-wife upsetter (240D), and for the life of me I can't seem to get it to come out. Are there any tricks? I don't care if I destroy the old pump, it's bad. I've already removed the lines from the lift pump to provide access to the hex on the primer, but I just can't seem to get anything to it. I'm down to a few major stumbling blocks to getting this thing on the road, and this is one of them. (I also have to adjust the throttle linkage, replace the rear brake line and mount an expansion tank for the 300cd radiator I put in it.)

Are you using a crow's foot wrench?

Unfortunately all my crow's feet are line style (not fully open). Anybody know what size it is so I don't have to buy a full set of 22mm+ crow's feet? I think it's 24mm, but I'm not sure.

you could remove the whole lift pump assembly to have full access to the primer pump.

17mm
 

I cut the box end off an old 17mm wrench. With the open end at 5", it worked fine. This was on an 83 240d. Make sure to get the old sealing ring out.

This is the old style, it's definitely larger than 17mm, I think I may try cutting a 24mm wrench...

See if you can get a pipe wrench or maybe vice grips on the body of the old pump.

Vise Grips from above. Crush and pinch. Then unscrew.

If you are someone else has some plumbing tools; see if there is a Basin Wrench.
It will squash the Hand Primer but the advantage is that it grabs down at the bottom of the Hand Primer.
See pics.

I think I'll give that basin wrench a try, it's cheap enough. Thank you

This. My IP is out for a rebuild, but I believe it's either a 19 or 21mm.

I had the exact same problem as the OP. Since I had to wait for the pump to arrive, I went ahead and picked up a set off eBay for under $20.

I couldn't drive the car for a week, but I saved lots of pain and frustration.

Basin wrench wins. The flats are closer to 24mm, and I didnt have a crowsfoot big enough. The pump came right out with the basin wrench

Just measured it, it is indeed 24mm...

My bad. Maybe I'm thinking of the newer Bosch replacement pump that I put back in.

My set of el cheapo crow's feet came with a 24mm. Probably the only time it will ever be used was to remove that busted plastic hand pump.

yeah, the new one was 17mm, if I could have located a 24mm straight crows foot locally cheap, I'd have gone that way. The sets I found locally ended at 21mm or less. As is, the basin wrench was 4.99 at harbor freight, and I don't even care that I went to harbor freight since I'll probably only only use it a handful of times... I'll actually probably lose it before the next time I need it.