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This is after 20K with the Baldwin prefilter. Truck runs great but used 2 quarts of oil in 5K. I know I'll need orings someday but is this just a normal black from 20K miles of fuel or is it from motor oil getting past the injector orings?
That, sir, is a clear indicator the oil you are "using" is getting past your injector o-rings and into your fuel. Time for o-rings...or just keep pouring oil into it.
Your fuel filter should never have any black in it from oil.
I ran my truck on straight motor oil. The only difference I noticed was egts were 100 degrees warmer and the exhaust smelt like motor oil. I'd say get the orings ready to do the job when it's convient in the near future. It's not a bad job to do anyways.
I hear this a lot. Bad injector O-rings cause black fuel filters.
I can see oil getting past worn injector O-rings and mixing with the fuel but how would it get back to the filter?
My understanding is that fuel is a one way trip to the respective head and dead heads. Is there a return line to the fuel bowl?
Not trying to be confrontational but just dont understand how this occurs.
Can this be a reliable diagnostic tool for bad injector O-rings?
The last fuel filter change in my truck looks just like the picture in the first post. I believe all of the filters I have changed looked like this since I bought the truck with 80K. I'm currently at 135K
The pressure regulator in the fuel bowl returns the excess fuel to the tank, that's no mystery there. The ICP (oil pressure that drives the injectors) starts at 500 PSI and goes up from there - to about 2800 PSI on a stock truck. Fuel pressure is about 60-65 PSI. When oil and fuel meet, oil is quite literally the 500-pound gorilla in the tube.
The pressure regulator in the fuel bowl returns the excess fuel to the tank, that's no mystery there. The ICP (oil pressure that drives the injectors) starts at 500 PSI and goes up from there - to about 2800 PSI on a stock truck. Fuel pressure is about 60-65 PSI. When oil and fuel meet, oil is quite literally the 500-pound gorilla in the tube.
Ok, so bowl back to tank. I get that. But the Head back to Bowl is where I get lost... and I understand high pressure oil and low pressure fuel with worn O-ring = mixing.
I have a dedicated fuel pressure gage post filter at the bowl. It never drops or varies more than 5-6 psi while the engine is running, except during startup. At startup the pump runs the PSI up to 60-65 and as I wait for the glow plugs to time out fuel pump shuts off and pressure drops to ~0 (on the gage). Maybe thats when the mix of fuel and oil can get from the injector back thru fuel line into the bowl? Once the engine fires up constant 60-65 psi at the gage. I dont see a negative number on the gage (high pressure over coming low pressure). Just thinking out loud...
the therory is the oil that gets past the injector O ring travels upstream and back to the fuel bowl..
like you said there is no return from the fuel in the head, hense its called a dead head system. oil under pressure is traveling backwards like a salmon swimming upstream..
Mine looked like that since new and used a quart between changes of 5000 mile (needed another quart at 5000 but just changed it).. Will have to see how they look since replacing
injectors. Oil consumption is a little lower but i think that is from the Lubrication Engineers oil cleaning out the oil rings.
2 quarts in 5000 miles might be a touch high but not that bad. Probably is the injector o-rings but could also be the turbo seals and other associated leaks and seepages contributing a little to the oil loss if they are also tired.
the therory is the oil that gets past the injector O ring travels upstream and back to the fuel bowl..
like you said there is no return from the fuel in the head, hense its called a dead head system. oil under pressure is traveling backwards like a salmon swimming upstream..
Yes. Correct.
My point is, its not happening when the engine is running. It cant. Unless my fuel pressure gage is lying to me as it never reads a negative number while running (its a dead head system).
It must be happening during KOEO waiting for glow plugs to do their thing. Right?
Many of us are running the FRx..which eliminates the cylinder dead head that was designed into these in stock form, and allows fuel to circulate through the heads and back to the tank. If the OP is still dead-headed, then it would be the oil pressure pushing back up into the fuel bowl like Camo said. I had this same black-fuel filter issue. Replaced the injectors with single shots/new o-rings and have not had a black fuel filter since. The o-rings on mine had about 250k, and there was clear evidence on the injectors themselves that the oil was leaking over to the fuel side (stains). The o-rings fell apart when I removed them from the old injectors.
Im at 290k with original injectors/orings. Ive experienced, when towing, high ipr %..64% to be exact that coupled with a long crank over to fire up. This was a couple yrs ago towing.
I never saw a black filter. Reason for response, im changinf filter today and will post pic. It hasnt been changed in over a yr/20k ish on it.
What did the fuel in the bowl look like? my filter may be a little darkish, but the fuel is always green.... (I run a long time between filter changes....)
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