Having a weird problem with random intermittent power loss and hars starting. I cleaned the whole fuel system and saw no problems. Pulled the lift pump today and the piston is stuck. How freely should it move?

a mystery to most of us.
The piston (which one?) should move freely.

Hopefully,


snapped_bolt

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'81 240D For now, a good place to borrow new parts
'80 300TD Probably will be put back into service!
'79 240D BACK IN SERVICE SINCE 09/16; limited use, oil leak. Guide pin r/sealed/replaced. Still a leak. Front crank seal....

Crumbs, it's rare for lift pumps to jam, any alternative fuels used?

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David


1996 Mercedes S124 E300TD - 129k - rolling restoration project -

1998 Mercedes W210 300TD - 118k (assimilated into above vehicle)

It had a greasecar system when we bought it. I bypassed that and put it back on diesel. Only had the car for 2 months and already had to rebuild the turbo. Money pit.

Its the piston under the large bolt on under the hand pump.

Can you post a picture, better able to assess any damage.

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David


1996 Mercedes S124 E300TD - 129k - rolling restoration project -

1998 Mercedes W210 300TD - 118k (assimilated into above vehicle)

I cant, says mobile cant post pics. I soaked it in pb blaster and carb clean and got some movement. I think its the problem.

should definitely move.

but, dont forget... if its still hooked up to the the fuel source, you are trying to pull all that fuel from the tank by moving that piston..... not easy.


so... "should move under the right circumstances" is more accurate

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No one has reported it on any of the Mercedes forums I have read but on other Bosch Inline Pumps I have seen the Piston Spring break or more rare the Plunger that pushes the piston break.

The Piston is a metal to metal fit. Rust or dirt can easily cause it to stick.

The below is for the lift pump on a 617.952.
Some pics in the below thread in post 5 and 11.
http://www.peachparts.com/shopforum/diesel-discussion/356205-can-617-injection-leak-into-oil.html

In post 5 you see the roller end taken apart. If you take apart that end you can put a small punch through the push rod hole and gently tap out the piston; of couse you need to have previously unscrewed the 30nmm Plug and removed the spring.

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84 300D, 82 Volvo 244Gl Diesel

I got it unstuck with a mix of pb blaster and carb clean, i call it the cleveland concoction from a guy i worked with at a motorcycle wrecking yard. Now my fuel lines are clogged with black goo. Pretty exciting. Im thinking ill just run new lines in aluminum and call it a day.

This sounds very much like 'diesel bug' - general causes included running only partially filled tank with WVO, hot oil splashes on the tank side resulting in polymerisation.



Photo courtesy BioFuels forum.

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David


1996 Mercedes S124 E300TD - 129k - rolling restoration project -

1998 Mercedes W210 300TD - 118k (assimilated into above vehicle)

Berryman's 0996 might clean that right up. It is safe on plastics. Let it soak.
Resist the urge to scrape, possibly damaging steel/composite sealing surfaces.


Cheers

snapped_bolt

__________________
'81 240D For now, a good place to borrow new parts
'80 300TD Probably will be put back into service!
'79 240D BACK IN SERVICE SINCE 09/16; limited use, oil leak. Guide pin r/sealed/replaced. Still a leak. Front crank seal....

There is parts inside that if they get rusted (the element) it would be ruined.

Also in order to clean it well it would need to come apart.

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84 300D, 82 Volvo 244Gl Diesel