Hi,

I'm curious if I need to remove the primer pump assembly to change the primer pump? Seems a little more difficult to remove than the ones on my other US-spec 300td turbo wagon. I've read a little about M vs MW pump but not clear on why the housing is set up different or if I have to remove it to change the pump. I hope this makes sense. I just don't want to create unnecessary probs. Any help would be appreciated. I attached data info below if that helps.

FIN WDB1231901F039529
Model 300 TD
Engine 617912 12 162185
Transmission 722405 02 167866
Order Number 0 4 513 19648
Order Location BELGIUM
Interior MB-TEX - BEIGE (155)
Paint 1 MIDNIGHT BLUE (904U)
Approx. Build Date 1984-12
Code Description
286 LUGGAGE NETS ON DRIVER RESTS L AND R
411 MECHANICAL SLIDING ROOF
420 AUTOMATIC TRANSMISSION 4-GEAR
438 ELIMINATION OF REAR SAFETY BELTS
440 TEMPOMAT (CRUISE CONTROL)
466 CENTRAL LOCKING MECHANISM
543 SUN VISOR WITH VANITY MIRROR, ILLUMINATED, LEFT AND RIGHT
570 FOLDING ARMREST, FRONT
584 ELECTRIC WINDOW LIFTERS (FRONT AND REAR DOORS)
593 HEAT-INSULATING GLASS, ALL-AROUND, HEATED REAR WINDOW PANE (SINGLE-SHEET SAFETY GLASS), BAND FILTER

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Of course we don't know why Bosch did it but the M type Fuel Injection Pumps have disc valves and the MW's have sort of T shaped hard plastic valves (with the hand primer further away from the Fuel Injection Pump Housing).

This is with the Fuel Supply/Lift Pump attached to the Fuel Injection Pump.
The shiny aluminum bodied Hand Primers with the hard plastic knob (usually but not always white) usually get destroyed when you try to remove them. The flat areas where the wrench is supposed to go usually round off because the aluminum is soft. However you can try using a "crows foot" wrench on an extension. You could get lucky and have it come loose.

The other method is to use a plumbers "Basin Wrench" which is a type of pipe wrench. You want the Plunger all the way down and screwed in and grip the aluminum body as close to the bottom as is safe and there is room to turn it.

Note that low quality Basin Wrenches tend to have much larger heads then the ones made of superior metal. The smaller heads a fit in tighter places which also helps in their use in plumbing.

You could remove the whole Fuel Supply/Lift Pump and put it in a Vice but you need to be extremely careful of the cast ears with the holes that the studs go through because they are thin and can break off.

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84 300D, 82 Volvo 244Gl Diesel

thx Diesel911.

I removed the whole assembly and used my vice. Put it back on but no luck on the start. I think it might have air in the system. I need to pump and bleed tomorrow and see if it starts.

thx again!

After installing the primer pump I initially did not pressurize the system enough(from what I read). Once I did it started up immediately. thx, now the upper cooler line.

anybody know what size wrench will fit that pump (original OM617 with white knob)? The biggest crowfoot wrench I have is 19mm and it’s way too small. Not enough room for an open-end wrench.

If it is the old style hand primer with the all shiny aluminum body even with the Crows Foot you have a poor chance of getting it off with that. The reason is the reason is the aluminum on it is extremely soft and a wrench on the flats normally rounds it or otherwise distorts it.

The basin wrench mentioned in the previous post has been used as well as some have managed to get a Vice Grips down there. Though the space is so small I don't know how the managed that.

A more complicated way is to remove the Fuel Supply/Lift Pump. However, that also has pit falls. On the MW Fuel Injection Pumps the lower to the rear nut is hard to get at.

On any of the Fuel Supply/Lift pumps the flange/ears of the pump are thin and a brittle casting. You need to turn out each nut and then go other side and loosen that one a little and do that all the way around.

Then you need to have a vice or something to hold the Fuel Supply Lift Pump in a manner that what ever you use like pipe wrench to remove the Hand Primer does not crack the flanges/ears off of the Fuel Supply/Lift Pump.

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84 300D, 82 Volvo 244Gl Diesel

It's not that complicated ^

Just grab the body with a vice grip, it'll turn.

The new primer takes a 17mm crows foot.

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1981 240D 4sp manual. Ivory White.

ok thanks to all-guess it’s off to harbor freight for a basin wrench..

??

Are you reinstalling it when you’re done removing it?
Because if you’re installing a new one, a basin wrench is totally unnecessary.

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1981 240D 4sp manual. Ivory White.

nah..it’s toast. I have a new Bosch one that’ll be taking its place.

He was saying don't use the basin wrench to install the new one. Also be sure to get the old copper crush washer off of the Lift Pump before installing a new crush washer.

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84 300D, 82 Volvo 244Gl Diesel

Vice grip is definitely the way to go on these (for anyone else reading), only if you don't care about the primer pump you are removing that is. The new one should be able to screw on by hand with a rag. At least that is what I have done, no need for a wrench. Although this is a fuel system so obviously check for leaks!

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