Fuel in Oil

[Fred Mc]

I have a GMPD4106 with the 8/71 engine and thought I might have fuel in the oil because of the oil appearance so I had an analysis done and my suspicions were confirmed today. The tech said it was 30% contaminated and to change the oil before running it which, of course, I will do.
Where would I start to look for the origin of this problem?

Thanks

Fred

[luvrbus]

Under the valve covers at the fuel jumper line tap each with a wrench if they ring they are good if you get a thud it is broken or loose if you have the non 0-ring flare type fuel lines,if the lines check out it could be a loose fuel stand or a injector   

[Fred Mc]

Thanks Clifford.

Fred

[chessie4905]

They say that the oil doesn't puddle up where the line comes out of the nut. Look for difference. Also look for washing of head surface around leak.

[Fred Mc]

"if the lines check out it could be a loose fuel stand or a injector   "

What is the fuel stand?

Thx

[eagle19952]

"if the lines check out it could be a loose fuel stand or a injector   "

What is the fuel stand?

Thx

what these are attached to...

[Fred Mc]

Thanks

Fred

[bevans6]

Fuel stand is at the back of the head, hex about 2" long, hardened very thin steel washer underneath, should be torqued to 45 ft lbs.  As said, the non-injector end of the fuel pipes connect to them.  My fuel leak was loose fuel stands, when I changed by system over to O-ring fuel pipes (part of installing my jake brakes)  I did them up "tight" with a 3/8 drive socket wrench.  "tight" with such a wrench is not 45 ft lbs by a long shot.  Took a long time to find, and the torque spec is buried in the manual.

Brian

[buswarrior]

At Big Transit, the ruthless way was to remove the covers, and then run the engine, watching for fuel washing.

Shut down and watch for more fuel washing.

Of course, having the oil black and dirty really helps...

The diesel will show itself as the thinner/lighter river in the heavier/darker engine oil.

If it is an injector, you're already in there, might as well send 'em all in,
cuz you know what'll happen if you just do one and button it up...

happy coaching!
buswarrior

[Fred Mc]

I haven't looked into this much other than removing a valve cover to familiarize myself with what I'm looking at in there.
But something occurred to me that might tie in with fuel leaking into the crankcase.

If the bus sits for an extended period of time_(say 3-4 months) the fuel system looses its prime and in order to start it I need to remove the secondary filter(last one the fuel goes through before going into injectors) and fill it full of diesel. It then starts right up.

At any rate could this give me a clue as to what might be leaking. i.e. crossover pipe, or fuel stands or injectors).

Thanks

Fred

[lostagain]

If you loose prime, I think (assume) the fuel just returns to the tank via a leaky check valve. Nothing to do with anything downstream of the secondary filter.

JC

[Fred Mc]

I realize the fule would return to the tank. However I think the reason that would happen is due to an air leak  in the system and was hoping this might help to pinpoint to area of the  leak.

[Utahclaimjumper]

Most busses have metal fuel lines from the tank to the filters,,these lines have a habit of corroding from the inside out to form a leak. All diesel fuel contains some moisture and when sitting for long periods will rust out the lines.>>>Dan

[Fred Mc]

I am just getting set up to look for the leak in the fuel system.I plan to use ciompressed air putting it into the fuel system after the fuel filter(disconnect the line from filter and put on an air fitting) and plug the return line to the tank. Escaping air should pinpoint the leak(I hope).I read somewhere NOT to apply more than 10lbs air pressure. What is the danger in applying too much pressure?

Thanks

Fred.

[luvrbus]

On the up stream side from the fuel pump over 10 lbs won't hurt it, the fuel pump is the weak link you can blow a seal with too much pressure,the fuel pump will pump it up to 65 to 70 lbs fwiw