Clifford, injector leaking question

[bevans6]

Hi guys.  Some may recall that I have an issue with fuel leaking into the oil.  I recently changed all of the o-rings on the fuel pipes, inspected them all for cracks and reinstalled.  Today I ran the bus for an hour, and gained about a half inch on the dipstick so I figure I didn't solve the problem.  On to step two.  I am going to rejig the fuel piping on the bus such that I can bypass the fuel pump and pressurize each head individually with my priming pump, and visually look for leaks.  I suspect the injectors, N-80's.  Several were pretty hard stuck when I first got the engine, I freed them up by pumping paint thinner through the heads.  Clifford, the question is - you've spoken of the old N-series injectors saying they are nasty old leaky things - where do they leak so I know where to look?  Where else do I look - fuel pipes, stand pipes, connections to the injectors, where else might I find a leak?

Thanks, Brian

[Dave5Cs]

What about fuel leaking past your rings in to the oil sump? I know you rebuilt, but I have had that happen in not getting the groove lined up properly.

Dave5Cs

[Utahclaimjumper]

 There should be no unburned fuel in the cylinders to leak thru the rings.>>>Dan ( It has to come from somewhere,, does your engine smoke excessively at all speeds including idle??0>>>Dan

[luvrbus]

Brian, they leak at the o-ring where the tube screws on to the body you need to pull the injector to solve the problem if it was dribbling you would have plenty of white smoke on start up are you sure the fuel stands are not leaking and all  washers are under the stands ? 

Be sure someone didn't screw 1/8 in plugs into the fuel pump to stop leakage and the pump seal is letting fuel in the crank case by not draining to the outside like it was designed to do

good luck

[bevans6]

I may have jumped the gun...  After obsessing about this all day yesterday I noticed that as the day went on and the engine finally cooled off, the oil level came back down to where it had been when I marked in cold.  This morning it was back exactly, as far as you can measure oil on a dipstick, to the same place it was yesterday morning at 50 degrees.  So I must have been fooled by thermal expansion of the oil, which I would not have credited.

Back to plan A, which is put a few hundred miles on and send out an oil sample.  Thanks for the advice, noted all.  I believe I will now research thermal expansion ratios of oil and try to do a calculation...

Edit:  If Google had been around when I was in school I'd be smarter than I already am...  Took all of 15 seconds to "research" thermal expansion ratios of oil, and solve my little conundrum.  Apparently there are calculators on the interweb to answer exactly that question.  If I started with 10 gallons of oil at 10 degrees C, which is roughly what I started with, and after running the engine for an hour got the oil temp to 80 degrees C (rough guess, probably close) then the volume of oil would have grown by a half gallon (to 10.49 gallons), which is very consistent with what I measured on the dip stick.

Brian

[Utahclaimjumper]

 Another thing I've noticed over the years is dipstick "creep" be sure to WIPE THE STICK AND RE-INSERT to get an accurate level when checking any fluid with a dipstick.>>>Dan

[OneLapper]

Brian,

I observed the opposite after installing a fresh 8V71 in my 4106.  I took a 800 mile test run and each time I checked the oil the level was low.   I would add a couple quarts each time.    And repeat.  Every stop the oil was low.   I got home and checked the oil the next day it was 4" over full!  It took me a while to realize that this new engine (factory new long block) takes 20-30 minutes for all the oil to drain back to the pan, making it impossible to accurately check the oil when stopped for less that 20-30 minutes.     

I don't know if this normal, but I didn't have this issue with the old engine.  Of course, the oil pressure was so low on that engine the oil probably couldn't get out of the oil pan!