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Author Topic: Leaking injector pump -- crankcase full of fuel  (Read 2977 times)

mjn

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Leaking injector pump -- crankcase full of fuel
« on: May 30, 2007, 12:03:47 AM »
My engine got a 5 month vacation over the winter.  This spring when I got ready to start up, I checked the oil and found that the crankcase was 2 inches over full.  There was a 2 inch layer of clear diesel floating on the top of the black motor oil.  Obviously the only way for that much fuel to get into the crankcase was through the injector pump.  I put off plans to start the engine until after I could tear into the IP to see what the problem was.

Over the weekend I pulled the IP expecting to find lots of damage.  Instead, I found a perfect pump with no obvious defects.  The pump barrel and plunger had a mirror finish with no scratches.  (There were some scratches on the tappet where it slid against the pump body which had not been properly deburred, but that is not related to my leak.)

Here is a schematic showing the insides of the pump and the suspect leak location.


I suspect that fuel (shown in red) is leaking between the pump barrel (blue) and the pump body (dark green).  This is not a tight fit.  The barrel slides into the body easily.  Under pressure, this will certainly leak. (The barrel is held pressed into place with the delivery valve nut not shown.)

The stock Changfa fuel tank is bolted directly to the top of the engine.  With a full tank of fuel, there is no more than 1 foot of fuel above the injector pump.  I have removed the stock tank and am using another tank located off the engine and another foot or so higher.  In the worst case, my fuel may be 3 feet above the IP.  I am speculating that the additional head is the cause of my leak.

Have others encountered leaking injector pumps?  Any suggestions for a fix?  I have considered RTV sealant, but I hate the thought of trying to get the goo into the right spot without getting it into the wrong spot.

In the meantime, I'm turning off the fuel when the engine is not running. (I should have been doing this anyway).
Changfa 195 7.5 kw ST.  WVO conversion http://martin.nile.googlepages.com/
Metro 6/1 DI Listeroid. Pumping water for fire control.
1933 Stover CT-1 hit and miss
1936 Farmall F-12 -- unrestored, still used to mow the field