Oil contamination in fuel tank on a 2,5 srx d4d

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FIRSTGEER
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Oil contamination in fuel tank on a 2,5 srx d4d

Post by FIRSTGEER »

I trust that one of the members can help fathom out a very strange problem a friend of mine is experiencing with his 2012 srx 2,5.
The vehicle starts normally and drive normally without any excess exhaust smoke BUT
The fuel filter started clogging and and the diesel is very dirty.
The fuel tank has been removed and cleaned on three occations recently and refilled with new diesel.The filter was changed but the problem reoccurs after a few days driving.

It seems as if the oil is somehow been pushed into the tank via the fuel return pipe.
The vehicle has been to our local diesel expert and he is also at odds with the problem.

Everyone ,who has some or maybe a lot of diesel experience,cannot explain how this problem is occuring .

Hopefully someone on the forum can assist.
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FIRSTGEER
LR4WD, Lockers, Crawler Gears
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Posts: 1536
Joined: Thu Sep 30, 2010 6:00 am
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Real Name: Tony Geer
Club VHF Licence: HC 109

Re: Oil contamination in fuel tank on a 2,5 srx d4d

Post by FIRSTGEER »

After giving this problem a bit of thought.Is there perhaps an oil feed to the injector pump for lubrication which somehow is leaking into the fuel bypass(return) to the tank.Possibly an O ring or seal ? Where are the diesel boffins ?
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Mars
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Re: Oil contamination in fuel tank on a 2,5 srx d4d

Post by Mars »

Is the oil level of the engine dropping? If it is that much oil it should be noticeable.

The only place where the engine oil and diesel come close to each other (that I know of) is in the cylinder head. The fuel return rail connecting all of the injectors bolts to a channel on the cylinder head with a banjo bolt. Then the diesel return is taken from the outside of the cylinder head via another banjo connector back to the high pressure pump IIRC. This is the only place where the diesel pressure could conceivably be low enough to allow oil to get into the line but I am a total loss as to how that would be possible. Normally the oil pressure in the cylinder head is not that high to begin with. It is much more likely that the high pressure in the diesel system would more likely cause diesel to leak into the engine contaminating the oil than vice versa.

It could also be possible that there is an oil feed to the high pressure pump but I am not 100% sure as the diesel actually serves as lubrication for the pump.The pressures here are so high that I would rather expect diesel to contaminate the oil. I am speculating here.
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FIRSTGEER
LR4WD, Lockers, Crawler Gears
LR4WD, Lockers, Crawler Gears
Posts: 1536
Joined: Thu Sep 30, 2010 6:00 am
Town: King WilliamsTown
Vehicle: 2,5 D4D Singlr Cab 4X4 Full OME suspension. snorkel.GMA aftermarket bullbar.
Real Name: Tony Geer
Club VHF Licence: HC 109

Re: Oil contamination in fuel tank on a 2,5 srx d4d

Post by FIRSTGEER »

Thanks Marnus.I tend to agree with you.I haven't seen the vehicle as it belongs to a friend about 60 km from me in the sticks.
I have looked at my own vehicle to trace the return pipe and also noticed it connecting to the bacl of the tappet cover and a mechanic friend of mine came up with the same theory as yours.

They are checking the return pipe and will let me know what they find.

Thanks for the input.
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