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Fuel getting in the oil on Mack vision


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Hey guys , I’m new here but i have a problem truck , guess the Mechanics can’t figure it out . Truck is getting fuel into the oil and don’t know where it’s coming from , is there a way to figure this out with out swapping injectors and pumps  and hoping that was the problem , i don’t want to dump a bunch of money in it and this is the third time I’ve had it looked at. Any help would be greatly appreciated 

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26 minutes ago, Bigcountry98 said:

Hey guys , I’m new here but i have a problem truck , guess the Mechanics can’t figure it out . Truck is getting fuel into the oil and don’t know where it’s coming from , is there a way to figure this out with out swapping injectors and pumps  and hoping that was the problem , i don’t want to dump a bunch of money in it and this is the third time I’ve had it looked at. Any help would be greatly appreciated 

Buddy what year is the truck?  Most common on the  Grey engine is  Fuel transfer pump  Then EUP Orings!

 

Edited by fjh
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Pull the fuel supply pump . Check for play in the shaft, should be none. You can spray soapy water on shaft while shooting air into the inlet and outlet abs check for bubbles,  other wise here’s  what we used to do . Put fuel dye in the primary (first filter) and run the engine for about 45 seconds to a minute. Shut off engine and  cap off fuel return line on the side of the block above the air compressor. Hook a air pressure regulator to the inlet of the primary fuel filter inlet and pressurize to 40-50 psi . Drop the oil pan and use  a black light and look for leaks. The EUP pumps will always seep fuel to an extent , but not enough between oil changes to cause issues. If you find a EUP leaking, they do make a 3piece lower o-ring for damaged bores . Also there there is a fuel galley plug behind the timing cover that can leak but it rare . 

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On my etech ,it was the injector oring that was bad.it would put fuel past the injector hold down cap threads and contaminate oil...you can tell by running engine shortly without valve covers .the culprit injector cap will have less oil sitting on it since the fuel washes it away.

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