I have a 85 f250 6.9 no turbo added that seems to be getting fuel in oil. Changed the fuel pump thinking it would be the easiest fix with one from napa. lot of grime from fuel around it. Changed engine oil and filter and ran 30 or so miles still seems to have diesel in oil when it runs down my finger quickly. Is that diesel and what do i need to do to stop it
15w-40 i don't remember the brand not rotella. not rising significantly. Yes rated for diesel engines. It was actually a bit low when i changed it. it seems to be seeping out the valve covers now too
Best way to verify fuel in the oil is by a lab testing an oil sample. Very popular lab here is Blackstone. You can find them on the web, and for a small fee they will analyze your oil. Call them and they will send you the bottle to collect the sample.
I would send a sample for confirmation first. Then we can discuss possible causes. Does it run good and smooth?
I don't know if this is true or just an old wive's (mechanic's) tale because I've personally never tried it. I've heard a few times if you take a shop towel, pull the dipstick and drip some oil on the towel, you will get an inner dark oil stain but if it's surrounded by an outer clear stain, that would be fuel in the oil.
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Heavy truck and diesel mechanic (thankfully retired after 30+ yrs)
'91 F-250 SC 4X4, 5spd. ATS Turbo, 3:55 diff.
Yes the wise tale from a mechanic I heard was that if u pull the dipstick and put some oil on your finger and it immediately goes down your finger then it has diesel in the oil. I guess i m wondering what paths does diesel have to oil. I know not injection pump. But would injections leak some when sitting and running and drain past rings. It can be a little hard to start even though glow plugs are working as they should be. It just turns over a few more times then normal.
I guess i m wondering what paths does diesel have to oil. I know not injection pump
That's not necessarily true, on the early pumps, if the front shaft seal on the IP went out fuel would get past it and drain into the crankase. The later pumps have a weep hole between the seal and mounting flange so fuel will leak out externally onto the valley pan.
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Yes the wise tale from a mechanic I heard was that if u pull the dipstick and put some oil on your finger and it immediately goes down your finger then it has diesel in the oil.
Seems like that would only tell you that it was hot oil versus cold.
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Heavy truck and diesel mechanic (thankfully retired after 30+ yrs)
'91 F-250 SC 4X4, 5spd. ATS Turbo, 3:55 diff.
There are several ways as mentioned above, druling injectors, bad seal on a mechanical lift pump on the side of the block, or the shaft seal on the injection pump, and there are two ways to test for diesel one is the oil sample as mentioned above the other is adding a floresent oil dye to a buck of diesel and running the engine for a while then get a floresent light and see if the dye is present in the fuel, the next step would be to determine the entry point of the diesel into the oil, more than likly if your engine has the mechanical lift pump then either replace the pump or get a block off plate and elminate the pump and add a carrier electric pump.
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1985 F250 XL XC LB 2WD with a 6.9 L IDI, C6 auto transmission, 4.10 rear diff, Goose neck, 5th wheel Kobalt Bed Tool Box Fel-Pro Gaskets, Hastings Rings, Clevite Bearings
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