1997 e300d lift pump questions
 

My vehicle is leaking from the gasket between the lift pump and engine. In addition there is a rectangle plate next to it that's about 6" x 3". That gasket is also leaking fuel. Can the gaskets's be changed on these two parts without major issue?

TKS Rod

It's not a big deal to replace those gaskets. I think crank TDC is where the lift pump stroke is at minimum. It's a PITA to install the pump against he plunger as in you could strip the iP threads if you use the bolts to seat the lift pump. On earlier models there's a choice of gasket for brass or aluminum side cover. When the side over gasket is bad, the bottom cover gasket is usually bad too. The IP has to come off to replace the bottom cover gasket unless you're particularly dexterous. FWIW, those gaskets leak engine oil. If you see fuel from that area, it's likely from the lift pump fittings, deliver valve holders or injection lines.

Sixto
87 300D

Sixto, a few days ago I observed a large puddle of diesel on the ground. My engine was dry and clean on top and sides after inspection. The lift pump and cover above it appear to have cork gaskets and have wet spots. There is no heavy puddle now but the gaskets are slightly dripping diesel. Just to clarify the plate above the lift pump should only leak oil and the lift pump if bad would leak diesel???

Rod

The long rectangular plate on the side of the pump should have a rubber gasket and if it leaks, it should only be oil.

You'll have to remove the SOV to reach all the screws and properly clean/re-seat the new gasket under the plate.

The lift pump as well, should only leak oil unless it has an internal seal failure.

I presume this means my lift pump has to be rebuilt. I saw a thread somewhere where someone mentioned they did it but it was a nightmare.

Thanks Rod

Clean the area with something like brake parts cleaner then observe the source of the leak. It's very rare for an MB lift pump to go bad. It'll probably be a supply line or loose clamp.

A fuel leak into the IP will manifest as fuel in the crank case. Some have noted the dipstick level rising over time.

Sixto
87 300D