I have a 94 Ram 1500 with original 5.2 engine. An employee put 10 gallons of diesel in the tank accidentally. After the engine begin running very poorly he decided he had received "bad" gas and put about 10 gallons of premium unleaded in on top. This improved the running of the truck (I was amazed) and he drove it approximately 80 miles. At the end of the day oil pressure light was coming on and the oil pressure gage was all over the place.

Checking the oil revealed crankcase was overfull by about 3 to 5 quarts. I changed the oil and the oil pressure returned to normal. I did not drain the contaminated fuel mix because the engine runs reasonably well. After another 80 miles or so, the oil pressure was beginning to fluxate. I checked the oil and the crankcase was again overfull.

What is going on? The oil is not contaminated with water and doesnt smell like gasoline. It is very thin though. Any ideas? I am going to drain the fuel tank before we use the truck again but I dont understand where the extra fluid in the crankcase is coming from.

Any input is welcome.

 

this is really weird... assuming your waiting about 15 min to allow oil to settle to the pan before checking the level....

i dont think the oil pressure and diesel fuel are realted. it probably really does have low pressure, as do a lot of these trucks after they get some miles on them. i dont think its possible for this to happen if YOU'RE putting the correct amount of oil in it, are you sure its as much as 3-5 qts? if its not milky and doesnt smell like fuel, thats just really odd 3-5 QTS is ALOT!!

the diesel should have been drained out of the tank. you may need new plugs and a fuel filter

 

Drained oil is thin. It is not milky. It doesnt reek of diesel or gas....but it smells like burnt combustion gasses.

It is definetly 3-5 quarts overfull.

Really weird thing is.....Engine runs good once up to operating termperature. Smooth idle. normal power.

In regards to putting in the correct amount....I did double check I only had 5 empty quart containers in my trash bin. (It is possible I lost the ability to count to 5 as I age but the good news is I still can! lol)

I am totally clueless how this can happen. In the 60's and 70's i saw this occur when mechanical fuel pumps failed and raw fuel entered the crankcase. I havent looked but I assumed the 94 has an in-the-tank electric pump.

I am glad someone else finds this weird. I thought I was losing my mind.

 

The diesel fuel is not being burned when it enters the combustion chamber. The gas is. The diesel fuel drains past the piston rings down into the crankcase and mixes with the oil. Drain the tank or ruin the engine, as the oil/diesel mix won't lube the engine well. On the bright side, your engine will be damn clean if the bearings aren't ruined. Is my theory anyway.

 

The diesel fuel is not being burned when it enters the combustion chamber. The gas is. The diesel fuel drains past the piston rings down into the crankcase and mixes with the oil. The oil pressure fluctuates because the diesel thins the oil and the oil pump does not pick it up as well, or the oil gets aerated since it is overfull with the diesel mixed in and again the pump doesn't pick it up as well. Drain the tank or ruin the engine, as the oil/diesel mix won't lube the engine well. On the bright side, your engine will be damn clean if the bearings aren't ruined. Is my theory anyway.

 

get the diesel out and change the oil and well go from there

 

It's normal for oil drained from a cold engine to smell of combustion gases, so that's not an issue unless you drained the crankcase immediately after running at full normal operating temperature for 15 minutes or more.

I've seen diesel added to gasoline tanks more than a dozen times, and have never seen the crankcase level changed by it. Clogged catalytic converters and failed oxygen sensors, and excessive carbon on the pistons and heads on tear-down, sure, but three quarts or more added to the crankcase in 80 miles? That'd take at least some blown rings and a really rough running engine because of them, and the oil would absolutely reek of diesel fuel.

For that matter, I'd expect the engine to be losing power with that much fluid in the crankcase, as the crank pins would be swimming in it on their down-strokes.

This scenario just doesn't add up to logical. I'd drain the fuel tank and blow out the lines, then compression test the engine before even thinking about anything else. If that looks okay, I'd drain and refill the crankcase with a new filter and new oil, and add just about way to darn much UV dye to five gallons of gas. Then if the level on the dipstick rises like that again, I'd drain the oil filter into a jar and look with a black light for fluorescence of my new oil. The absence of fluorescence would prove that it's not fuel getting into the crankcase, and have me looking at the possibility of human intervention.

I suspect human intervention because the lack of fuel odor or coolant loss eliminates the only two on-vehicle subsystems that hold enough liquid to have added between six and ten quarts so far to the crankcase. But I never, ever start looking at humans until I've proven the problem at hand cannot possibly have any in-system explanation.

 

didnt we have a member that put in a different fuel and it killed the whole motor? i would not have let that run at all with deisel fuel in it....i would have demanded he drain tank, and refund that 10 gallons since it was HIS mistake....

 

even blown rings could not account for this! with this much supposed FUEL escaping past the rings, THEY ARE NON-EXISTENT!! If the rings are in that poor of a state, i dont beleive the engine would run, much less run without ill effect.

as was previously stated if the oil isnt milky and doesnt smell foul of diesel fuel, something IS AMISS!

 

The additional fluid is coming from somewhere. Only choices are fuel, or coolant. Coolant would be patently obvious. So, that leaves fuel. Running diesel in it, which really isn't going to burn very well in the low compression, spark fired engine....... is going to wash the oil off the cylinder walls, and blowby is going to be rampant. Also, since there is no oil there, the rings are going to be wearing the cylinder walls at a horrendous rate.

Drain the fuel tank. Take if off. Clean it out. Flush the fuel line. Put in some reasonable gas. Do a compression test.......

I am curious how he even got the diesel fuel in there, the nozzle on diesel pumps won't (shouldn't) physically fit in the fill tube.