1978 240D lift pump valves - Page 2 - PeachParts Mercedes-Benz Forum

Markp · #16 08-02-2012, 04:18 PM

I have the same pump, came off an early SD. Not sure if it was original, but no reason to think otherwise. I decided to rebuild a "regular" LP I had instead of using the early one.

BodhiBenz1987 · #17 08-04-2012, 04:23 PM

Think I figured out what's supposed to go where. I decided to read through the whole FSM fuel system section (as opposed to just the part specifically about the lift pump) and found this graphic that includes my type of pump (according to the charts this pump was used in US 240Ds in 77, 78 and 79). It appears the suction valve goes under the primer pump. I have this vague recollection of finding a spring under the orginal primer pump when I went to replace it two years ago and taking it out thinking it was part of the hand pump (but then wondered if I totally imagined that). It worked fine for months though. At any rate, I have now reassembled it as shown in the FSM (took a pic of it laid out, below) and tested it with a mitivac ... it holds vaccuum.
Going to stick it back on and try pumping fuel through, but have one question: Since a lot of oil came out of the back of the pump, should I try to pre-lube the roller/plunger on the back? Should I just add oil to the crankcase to accomodate for oil lost out the IP?

Stretch · #18 08-05-2012, 04:12 AM

Quote:

Originally Posted by BodhiBenz1987

... I have this vague recollection of finding a spring under the orginal primer pump when I went to replace it two years ago and taking it out thinking it was part of the hand pump (but then wondered if I totally imagined that).

Ahhh memories - are they real or are they not!

Quote:

Originally Posted by BodhiBenz1987

...

It worked fine for months though. At any rate, I have now reassembled it as shown in the FSM (took a pic of it laid out, below) and tested it with a mitivac ... it holds vaccuum.
Going to stick it back on and try pumping fuel through, ...

Great stuff!

Quote:

Originally Posted by BodhiBenz1987

...

but have one question: Since a lot of oil came out of the back of the pump, should I try to pre-lube the roller/plunger on the back? Should I just add oil to the crankcase to accomodate for oil lost out the IP?

I wouldn't get too messy trying to oil the rollers - a light smear of engine oil will be just fine. If you ever see a little bottle of engine builders' assembly oil then that's the perfect stuff for this type of situation. But again you only need to coat the surfaces.

If I were you I'd try and get out as much of the mucky crudy oil that gets left in the bottom of the IP - the stuff that came out of my spare IP (shown in link I posted before) was really grim. No wonder new oil turns black after two cranks when there are pockets of this evil stuff sitting in the oil ways!

cho · #19 08-05-2012, 05:10 AM

Quote:

Originally Posted by BodhiBenz1987

Should I just add oil to the crankcase to accomodate for oil lost out the IP?

just wondering ..... how much oil did you lost?

TX
ChO

.

guyonabuffalo · #20 10-31-2015, 09:54 PM

Sorry to revive such an old thread but I am planning on rebuilding my lift pump as part of a total fuel system overhaul. So far, this is the only thing left to do. I took some photos of my lift pump. OP (BodhiBenz1987), how did your rebuild go? Too bad this thread died.
I am attaching a photo of my pump, which looks the same as the OP's but is for an OM617 5 cylinder.

guyonabuffalo · #21 10-31-2015, 10:01 PM

Also, I got this kit. So I am going to assemble mine the same way. I will do this next weekend, so hopefully someone who has done this to the same pump can chime in with their responses.

Diesel911 · #22 11-01-2015, 01:16 AM

Quote:

Originally Posted by guyonabuffalo

Also, I got this kit. So I am going to assemble mine the same way. I will do this next weekend, so hopefully someone who has done this to the same pump can chime in with their responses.

The Fuel Supply/Lift Pump you are showing is from an MW-type Fuel Injection Pump.
The M-type Fuel Injection Pumps on the older 240Ds use a different Fuel Supply Pump and use disc Vales and have differences in assembly.

It is important to change the little O-ring in the Picture. you need to push down a bit on the Roller Assembly and carefully pry out the Retainer ring and remove the Roller Assembly. Pull out the Push Rod and and the O-ring Groove and O-ring are inside of the bore the Push Rod goes into.

Remove all of the old Copper Crush Washers before installing the new ones.

BodhiBenz1987 · #23 11-01-2015, 01:26 AM

Hi, sorry for the lack of follow-up ... this was part of a saga that just went on and on and was something of a wild goose chase. In short, the rebuild went great, the pump worked and still works well. It was not the problem that I was trying to solve back then (recurring constant airlock in the IP) ... that turned out to be a bad new injector. Nonetheless the fuel pump is fixed and working well ... well, it was last I drove the car ... it's in rust purgatory at the moment.
If I recall right, I did the assembly just as the photo depicts. I don't think you really need to remove the pump to replace the valves/springs ... I think I did in order to fully inspect it. If you plan to remove it: I did replace the gasket between the pump and IP housing. I would suggest removing the top line from the pump before removing the pump. I took the pump off first, and had to bolt it to a block of wood to get the line off (I don't have a vice). Taking the pump off dumped a fair amount of fuel and oil under the car so stick a pan under there.
Hope it goes well ... if you have any questions I'll try to remember.

BodhiBenz1987 · #24 11-01-2015, 01:30 AM

Quote:

Originally Posted by Diesel911

It is important to change the little O-ring in the Picture. you need to push down a bit on the Roller Assembly and carefully pry out the Retainer ring and remove the Roller Assembly. Pull out the Push Rod and and the O-ring Groove and O-ring are inside of the bore the Push Rod goes into.

What's the result of not changing the o-ring/having a bad one? Fuel in oil? I never took apart the roller assembly, just did the intake/outtake valves and springs and the copper rings.

Diesel911 · #25 11-01-2015, 06:06 PM

Quote:

Originally Posted by BodhiBenz1987

What's the result of not changing the o-ring/having a bad one? Fuel in oil? I never took apart the roller assembly, just did the intake/outtake valves and springs and the copper rings.

If you only bought the Valve Kit it does not come with the little O-ring.

A few Members have had the Oil inside of the Fuel Injection Pump get sucked into the Lift Pump and it gets burned as Fuel. The only symptom is your crankcase oil level begins to fall for no apparent reason (though to tell that if you have external oil leaks).

If it gets extremely bad Fuel will come out of the Lift Pump and get mixed with the crankcase oil and when you check you dipstick your Oil level will be higher.

BodhiBenz1987 · #26 11-01-2015, 06:23 PM

Quote:

Originally Posted by Diesel911

If you only bought the Valve Kit it does not come with the little O-ring.

A few Members have had the Oil inside of the Fuel Injection Pump get sucked into the Lift Pump and it gets burned as Fuel. The only symptom is your crankcase oil level begins to fall for no apparent reason (though to tell that if you have external oil leaks).

If it gets extremely bad Fuel will come out of the Lift Pump and get mixed with the crankcase oil and when you check you dipstick your Oil level will be higher.

OK, that makes sense. My car does burn a bit of oil but it hadn't been enough to set off any particular concern at its mileage, I assumed normal from wear. If/when I get it back on the road maybe I will look at that.