Lehman 120 Injector Pump oil thinning

[Skip Sunnell]

When doing recent servicing the injector pumps on the twin Lehmans on my CHB trawler, I found thin oil when draining one of them. This was the first service I’ve done on them since owning the boat. Is it possible that fuel could be getting into the oil reservoir on Lehman 120 HP six cylinder engine injector pumps? There is such a small oil reservoir in these pumps, I find it odd that one of them had thinner oil in it than the other one.

 

[Dashash]

My understanding is that it is normal for fuel to get into the oil in the injector pump, hence the relatively short (50hr) oil change interval.

 

[Comodave]

The oil in the injector pump should be on a 50 hour change schedule to start with. On that engine this is a common issue. Each engine is a bit different so the oil change interval may be different between engines. Start at 50 hours and gradually extend the interval until you can see some dilution, then back off a bit and that is the interval for that engine. Be careful with the screws since the pump housing is aluminum if I remember correctly and easy to strip out.

 

[READY]

Suggest you get hold of the Lehman service manual as that contains very valuable info including this service requirement. Great engines that may last forever with reasonable maintenance.

 

[Comodave]

The main resource for Lehmans is American Diesel. Brian is the guru. 804-435-3107.

 

[BruceK]

Suggest you get hold of the Lehman service manual as that contains very valuable info including this service requirement. Great engines that may last forever with reasonable maintenance.

A mine of information if you get one. You don`t know what you don`t know. Lots of good stuff in it,exploded diagrams,part numbers, warnings,etc.

 

[psneeld]

The are at least several "Lehman" manuals out there for different versions of Lehmans.

One such manual is for the Sabre Lehman which is pretty commonly posted or exchanged online, yet talking to American Diesel, Brian referred me to another manual for my Lehman. I don't remember what triggered his suggestion or how all the Lehman versions are different.

Even then, my boat came with a Lehman 135 that was repowered by a 120 block but used many of the old 135 parts . Took a couple years working with AD and Bomar to be able to get things straightened out.