Oil leaking from fuel pump- Help

truckdoctor

truckdoctor

Member
Hi all, could someone offer a little advice regarding my fuel pump , it keeps dripping engine oil from the vent hole in the side. The seal was replaced a few hundred miles ago . Coincidently the rear crank seal has started to leak a bit so I'm wondering if it could be building up back pressure? Any ideas what to look for please.
Thanks,Steve
 
I think checking the breathing system would be a wise move. Once you know that is all clear, then you can eliminate that as the cause. If it is blocked you just develop more and more leaks, and end up chasing the leaks from one place to another.
 
Make sure the two flame traps are clear, and the four hoses that connect to them, plus the pipes that they go into on the rocker covers, and most importantly (because they seem to get blocked up solid) the brass pipes into the carbs. Then do the same with the engine breather filter into the air filter housing, and it's fitting into the back of the block.
 
Hi Steve,

Even with the engine breathers all clear, the mechanical fuel pumps will leak oil fairly quickly when put to use, in one degree or another. I found the application of some Permatex #3 to the main diaphragm shaft around which the oil seal fits, along with a coating on the underside of the diaphragm chamber, can slow down the oil leaks. Use a straight edge and inspect the surface of the diaphragm chamber along with the section where it meets with the timing cover. If these are distorted in any way, then again that will quickly lead to oil leaks.

Ron.
 
SydneyRoverP6B said:
Hi Steve,

Even with the engine breathers all clear, the mechanical fuel pumps will leak oil fairly quickly when put to use, in one degree or another. I found the application of some Permatex #3 to the main diaphragm shaft around which the oil seal fits, along with a coating on the underside of the diaphragm chamber, can slow down the oil leaks. Use a straight edge and inspect the surface of the diaphragm chamber along with the section where it meets with the timing cover. If these are distorted in any way, then again that will quickly lead to oil leaks.

Ron.
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Thanks for your advice Ron, checked all of the above and the easily pass air and no blockages. So any recommendation or mods for this pump seal please?
What happens if I block up the hole in the side of the pump? Will the engine oil destroy the diaphragm, I wonder.
 
Hi Steve,

Apart from using a little sealant on the diaphragm shaft, there isn't really very much that you can do with the oil seal. Is it still nice and supple?

I have never blocked the little hole in the side of the diaphragm chamber, but I imagine that the pump won't work if you close it off.

Ron.
 
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