What type/size wrench to remove injector pump air filter? - PeachParts Mercedes-Benz Forum

Marrs · #1 02-12-2012, 07:52 PM

I'm going to replace the metal cased air filter that sits on the side of the injector pump on my W111 coupe, but the space to fit a wrench is incredibly thin. I've seen things called "flat wrench" or "thin wrench" that look more like a wrench stamped or laser cut out of a piece of thick sheet metal rather than forged, is this what I need to remove the filter and what size is needed? Also, any gaskets or o-rings involved? Doesn't appear so but I want to be prepared.

wbain5280 · #2 02-12-2012, 10:07 PM

I had to change the filter too. I just happened to have a SEARS Craftsman wrench that worked. It's 3/4 on one end and 7/8 on the other, the 3/4 size is the one you want, 19 mm. The other side of the wrench has U.S.A. and 44474 on it, which may be the tool number. The 3/4" open end base is 0.23" thick and the ends are 0.21" thick.

Be aware that this filter uses a threaded sleeve. It fits in the injection pump and the filter screws into it. If you undo the filter and its threaded screw diameter is larger than 0.55", the sleeve has to be removed from the old filter and threaded on the new filter. It's not hard and you do have to make sure the plunger under the cylindrical thermostat housing, with the water pipes, must move up and down. If it doesn't, you must free it.

Please let us know what happens.

Marrs · #3 02-13-2012, 12:39 PM

Quote:

Originally Posted by wbain5280

It's not hard and you do have to make sure the plunger under the cylindrical thermostat housing, with the water pipes, must move up and down. If it doesn't, you must free it.

Please let us know what happens.

Thanks, I'll go buy that specific wrench, we have a Sears tool shop nearby. (Edit: I'll probably just grind down a wrench I already have to make it thin enough since I have several duplicates of each size.)

How do I test the plunger to see if it is moving? Also, to be clear, you're saying that sometimes the sleeve remains in the pump and sometimes comes out with the filter so I just need to make sure the sleeve stays since my new filter doesn't come with one?

wbain5280 · #4 02-13-2012, 10:01 PM

Or just unscrew it from the old one. I'm just letting you know. As for testing, stick your finger on the plunger and push on it. You will know. (Take off the thermostat housing and the thermostat, the one on the injection pump).

Marrs · #5 02-13-2012, 10:18 PM

A few things to add since I just put the new filter on my car. The one on my car was very old and almost no air was able to pass when we took it off and blew through it so it was definitely ready for a new one ($37.50 from Classic Center). The shop let me borrow their wrench, and they had the perfect type, called a Tappet Wrench, I ended up using the 17mm side.
Also, to help others out, my old air filter didn't seem to have a MB part number so I am not sure it is original to the car and it was flatter than the one I replaced it with. The replacement offered two choices depending on date of production, one with a larger diameter threaded post and one with a smaller diameter post, the bolts were 17mm & 19mm respectively. My car used the 17mm as stated and there was no sleeve on my filter or left on the pump so that may only apply to the larger filter or it may be an adapter of sorts to fit the smaller filter in the larger filter hole. There was a washer which was also replaced but didn't come with the filter but you can match to your old one at the hardware store or just reuse the old one since it's not vital to replace the washer here.

The car is definitely running smoother and surely helped get the car closer to how she ran when new.