Rebuilt my spare lift pump today....Inside is a steel piston about the dia. of a nickle about 3/4" long driven by approx 1" long,7mm dia. or so steel rod that is driven by the little steel roller slider that rides on the IP cam....
This piston lives under the big hex cap with a hefty spring that keeps the whole thing riding the IP cam lobe....
Input and output check valves are plastic and look like small flat top golf tees with delicate springs to return them to the polished chrome seats...about 1/2" dia and 3/4" long plastic valves....

The piston has no rings and just sucks and pushes the fuel from the input valve to the output valve...thats all that is in it......solid little thing.....the plastic disappointed me for a piece of quality German machinery but must work ok since they last so long.....

Also there is a small O-Ring that keeps IP oil from seeping past the piston push rod.....hard to see but I am lucky to have a Bosch IP shop owner as a friend that made sure I knew about the o-ring ...I would have missed it during the rebuild probably.....It did have a lot of slack around the rod....quick and easy to rebuild....

I rebuilt it because I have stretched my ball/spring to 31mm and still only get about 14 PSI out of the pump...will replace tomorrow with my rebuilt Lift pump and post back......

The 0-30 psi gauges I use only have about 1~2 psi oscillation above idle...made in Ohio ...NoShok brand 900 series glycerin filled...bout 25 bucks each.....they have a website...

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1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)