31.5% Fuel Dilution, possible causes?

[dukedrummer89]

What are the possible culprits for fuel dilution in these motors. I would have to say a bad lift pump.


My dads truck (1993 F250 eclb 4x4 7.3idi auto) had 31.5% fuel in the oil. Its has 245k one owner miles, its on the 2nd or 3rd lift pump.


It had 6900 miles on the oil. Iron was up, the rest of the wear metals were on trend with previous samples


We put a new lift pump on it today, if it doesnt fix it where else should we look?

 

[flareside_thun]

There's really nothing else unless your IP is leaking under it's gear cover or the injectors are sitting in the heads dripping when the truck is not running....

 

[icanfixall]

Thats about all the ways fuel can enter the oil side. How many miles are on the injector pump...

 

[dukedrummer89]

Thats about all the ways fuel can enter the oil side. How many miles are on the injector pump...

Id have to ask my dad, but i would say less than 5k... it was just rebuilt this winter by a local pump place

 

[MIDNIGHT RIDER]

The diaphragm-type lift-pump can fail and pump fuel into the crank-case.

Also, the main shaft-seal of the injection-pump can turn loose a bunch of fuel into the engine.

Since the pump was recently rebuilt, I would suspect it as the culprit.

One easy way to find out would be to temporarily bypass the lift-pump, routing the fuel through an electric-pump instead, change the oil, put several miles on it, and look for the fuel in the oil.


Does the dipstick level gain quickly ??

The lift-pump is only capable of maybe 7-PSI and would still have to be supplying fuel to run on; whereas, the injection-pump case-pressure is more like 300-PSI and that can dump a bunch of fuel in there quick.


On a re-read of your initial post, I see that you have already installed a new lift-pump.

Carry on and the results will show you whether the injection-pump is at fault.

 

[idi traveler]

My oil became so contaminated with diesel that it wouldn't hold oil pressure at idle. The oil only had 2500 miles on it. I pulled injectors and 5 of them were wet! I replace them with some good old one(?), and changed the oil. The truck runs much better now but one injector seems to cut in and out.

 

[Agnem]

I had this problem 2 times in the 80's and both times it was the IP. This was before they started adding the weep hole. But the rebuilders do not always take the care to use only a weep hole equipped core, or to put a weep hole in.

Reason #3 for why you should run an electric fuel pump.

 

[Militaryman445]

I wonder if this is happening to my truck. Mine doesnt hold oil pressure at idle but it runs fine so I thought it was just the gauge. I guess I should look into this.

 

[towcat]

I wonder if this is happening to my truck. Mine doesnt hold oil pressure at idle but it runs fine so I thought it was just the gauge. I guess I should look into this.

you measure oil pressure on these trucks at 2000 rpm. (35psi min).
idle oil pressure can be as low as 7psi and nothing gets hurt.

 

[Militaryman445]

you measure oil pressure on these trucks at 2000 rpm. (35psi min).
idle oil pressure can be as low as 7psi and nothing gets hurt.

Oh really? So its ok for my Turboed IDI to run at idle on the furthest left side of the gauge? Actually it goes all the till the gauge cant turn anymore and then sometimes itll bounce back and forth some too. I think my gauge is iffy but it holds solid at almost 1/2 (more like 3/8ths) of the gauge when its anywhere above idle.

 

[hesutton]

Oh really? So its ok for my Turboed IDI to run at idle on the furthest left side of the gauge? Actually it goes all the till the gauge cant turn anymore and then sometimes itll bounce back and forth some too. I think my gauge is iffy but it holds solid at almost 1/2 (more like 3/8ths) of the gauge when its anywhere above idle.

What psi do you have at idle? If you are talking about the factory gauge, then forget about it. That thing is useless. Without an aftermarket oil pressure gauge, you have no idea what is really going on with your oil pressue.

Heath

 

[Militaryman445]

What psi do you have at idle? If you are talking about the factory gauge, then forget about it. That thing is useless. Without an aftermarket oil pressure gauge, you have no idea what is really going on with your oil pressue.

Heath

Yeah, Im talking about factory. I have only had the truck for about 2 weeks and have not had time to do all that to it... Where can I get a good oil pressure gauge from?

 

[hesutton]

Yeah, Im talking about factory. I have only had the truck for about 2 weeks and have not had time to do all that to it... Where can I get a good oil pressure gauge from?

I like Autometer, but ISSPRO, or VDO make good quality gauges as well. I don't know why Ford used those silly senders, but they just move the needle to a "normal" range on the gauge if there is 7 psi. Don't really know what the pressure is, but it is at least 7 psi if the needle has moved.

On my truck, the stock gauge will barely be in the "normal" range but I have 50 psi on my Autometer gauge. I don't trust those factory gauges.

Heath

 

[Militaryman445]

I like Autometer, but ISSPRO, or VDO make good quality gauges as well. I don't know why Ford used those silly senders, but they just move the needle to a "normal" range on the gauge if there is 7 psi. Don't really know what the pressure is, but it is at least 7 psi if the needle has moved.

On my truck, the stock gauge will barely be in the "normal" range but I have 50 psi on my Autometer gauge. I don't trust those factory gauges.

Heath

Hmmm... You got a good link to the autometer?

 

[Militaryman445]

Would this work?
http://www.truckcustomizers.com/products/auto-meter-2312-autogage-oil-pressure-gauge.html