gas in the diesel tank - PeachParts Mercedes-Benz Forum

nohuti · #1 02-14-2009, 10:47 AM

My friend's wife filled the tank of his 1999 E300 TD with gas. She drove it until it quit. Will this be repairable? I sold him this car and I still help with service so it will fall to me to fix it. It would be my idea to drain the tank and all the fuel lines and refill it with fuel and try to start. To say the least, I am very upset. nohuti

my cars 1998 E300 TD 115000, 2005 E320 CDI 78000

JonL · #2 02-14-2009, 11:11 AM

How long did it take for it to quit after she filled up with gasoline? How much diesel was still in the tank when she added the gasoline?

By the way, a mixture of gasoline and diesel in a tank is much more hazardous than either gasoline or diesel by itself. Here's why. Gasoline is very volatile, so space in the tank fills with a very rich mixture of gasoline vapor and air. Too rich to easily ignite except in very cold temperatures (when the gasoline doesn't vaporize as easily). Diesel is much less volatile, so the space in the tank is filled with mostly air and very little diesel vapor -- a mixture too lean to ignite easily except in extremely hot temperatures. Gasoline and diesel together... the space in the tank fills with a mixture of vapor and air that is potentially easy to ignite. Even static electricity from the fuel sliding down the filler neck is potentially a source of enough energy to cause an explosion. So be careful!

Oracle12345 · #3 02-14-2009, 11:24 AM

you may have to replace all the fuel associated parts on your car. Which means injectors, lines, pump etc. I know if you put diesel in a gas car you have to replace everything in the fuel system which is a lot of bucks.

draining the tank and lines wont work.

Mike D · #4 02-14-2009, 11:37 AM

The hidden danger in the gasoline is the fact diesel provides lubrication and cooling for the injection related parts.

Gasoline won't affect the lines (for the relatively short amount of time it was in the system) but it can wreak havoc with the injectors and pump components. It can also cause problems with the pistons and cylinder walls.

Best thing to do is to completely drain the system, flush the system with clean diesel using an external pump, re-fill with diesel and cross your fingers.

Expect trouble "down the road" from the worn parts. You MIGHT get lucky.

123Guy · #5 02-14-2009, 11:58 AM

It may not be a prolblem - remember that in the old MB's the owner's manual said you could mix gas and diesel 50/50 in very cold weather.
I had that happen about 10 years ago, got about 80-90% gasoline - Elvira ran really bad, I pulled over and had her towed to MPH, a local MB shop. Mike drained the fuel, put diesel back in it and that was it. 100K miles later, still no problems.

Mike D · #6 02-14-2009, 11:59 AM

Quote:

Originally Posted by 123Guy

It may not be a prolblem - remember that in the old MB's the owner's manual said you could mix gas and diesel 50/50 in very cold weather.
I had that happen about 10 years ago, got about 80-90% gasoline - Elvira ran really bad, I pulled over and had her towed to MPH, a local MB shop. Mike drained the fuel, put diesel back in it and that was it. 100K miles later, still no problems.

Key phrase here is "the old MB's"and the fact you still had the diesel to provide lubrication.

TMAllison · #7 02-14-2009, 12:00 PM

I dont imagine it would have run too long on RUG; too volatile and would ignite as soon as the inj began to pop. The ignition timing of that fuel would be way off.

Drain the tank, disconect the fuel lines at the back of the tank and drain them, pop a fuel line or two off of the SOV to drain them back, install a new main fuel filter (pre-filled), prefill the pre-filter, dump in 10 gals of diesel, get a second battery, raise the rear end with a floor jack a couple of inches, and start cranking 30 secs at a time resting 10 secs. After 3-4 crank cycles stop and recharge the batt and let the starter cool for 10 minutes then have at again.

If you have compressed air or a mittyvac you might try to push or pull some fuel up from the tank by disconnecting the return or supply lines at the left side firewall.

Its gonna take a while to prime it and get it to fire again.

nohuti · #8 02-14-2009, 12:06 PM

Thankyou everyone for all the help. I am on the way to get empty buckets and pumps and to see if maybe we[ my friend and i] will get lucky. The other part of this is I may need to loan him one of my cars which I would! nohuti

TMAllison · #9 02-14-2009, 12:13 PM

Getting the nose down (or raising the rear) and filling at least 1/2 full helps immensely when priming.....

Jeremy5848 · #10 02-14-2009, 12:47 PM

Make the wife help. It will encourage her to remember next time.

el sea · #11 02-14-2009, 07:54 PM

"The solution to pollution is dilution"....

Cold weather, artic type truckers often mix gasoline in the diesel fuel during extreme cold spells. However in Washington you will not be seeing thoses conditions. I would drain out most of the gasoline and refill with diesel. If you experience any problems with the fuel system (which I don't think you will) then address them accordingly.

yellowrosefarm · #12 02-14-2009, 09:23 PM

I can't speak for the Mercedes diesel specifically, but since I'm a tractor mechanic, I've seen this situation with a lot of other diesels. None have been harmed that I am aware of. Just drain out what's left in the tank and bleed the system like you would if you had run out of fuel. Diesel's seem to be a lot more tolerant than a gas engine in the reverse situation. I saw a 17 HP Kawasaki lawnmower engine that had run on a diesel-rich mixture until it lost compression and quit. Every ring on the piston was broken into multiple pieces.

rcounts · #13 02-14-2009, 09:41 PM

Well, I guess I'm just unlucky (though I already knew that)

I was running on fumes and got 5 gallons of fuel at a local Shell station. I got it from the diesel pump (still have the receipt to this day) and drove 20 miles home. By the time I got there it was knocking, overheating, had no power, etc.

I removed the fuel filter and the contents REEKED of gasoline. Took the fuel filler cap off and sniffed the filler neck, and same deal - strong smell of gasonline. It took some time to diagnose but in the final analysis the rod bearings were toast on cylinders 2 and 3.

Best I can figure the fuel was probably 50% or more gasoline and the excessive early detonations hammered the rod bearings.

JonL · #14 02-15-2009, 10:36 AM

Quote:

Originally Posted by TMAllison

I dont imagine it would have run too long on RUG; too volatile and would ignite as soon as the inj began to pop. The ignition timing of that fuel would be way off.

I think that gasoline actually burns more slowly than diesel fuel. (Octane is a measure of autoignition resistance, while Cetane is a measure of autoignitability... sort of.) I think what happens with gasoline in a diesel is that it is injected and doesn't start to burn at a rate controlled by the injection process. It all gets injected before it ignites, sits around in the chamber for a bit too long, and then all goes up at once, in an uncontrolled and too rapid fashion. The end result is similar... lots of knocking from too-fast combustion.

As far as the lubrication of the pump and other parts... I doubt that any damage at all would be done in the few minutes she tried to drive.

My guess is that a good flush of the system will be all she needs.

81300sd · #15 02-15-2009, 11:01 AM

diesel in a gas system does not harm any of the fuel delivery components as previously mentioned.

Fairly certain MB never printed anything that said 50/50. They did print 10% RUG mixed in the winter.

JonL has it right. Gasoline is harder to ignite than diesel