Darwin Award for this Year - PeachParts Mercedes-Benz Forum

GaryF · #1 10-31-2009, 05:05 PM

Hi Guys,

I think I've won this award, put 50 Litres of diesel in my '73 450SLC earlier today and managed to drive about 100 yards from the station before it died and I realized my mistake...well the pumps are right next to each other !!
Its back home now thanks to a flatbed and I have a guy coming over on Monday with a pump to drain it.
Doing a search it seems EFI doesnt like this stuff too much, have I done permanent damage and need to swap parts or will a flush and re-fill be likely to resurrect her?

Thanks for any advise,
Gary

junqueyardjim · #2 10-31-2009, 05:21 PM

It won't run on diesel, but I don't think anything would be damaged. However, before she will start up, you will have to do more then just drain the tank. I would start right at the engine and let it bleed out any open connection, give it a little help with air or even starting fluid. Starting fluid will really clean it up. When you think you have the lines clear of the diesel, then I would start it up, (with gasoline in the tank) and try to get it running on starter fluid until it will run on its own. Should not be to difficult.

compu_85 · #3 10-31-2009, 05:24 PM

I'd consider replacing the fuel filter too.

-J

Pooka · #4 10-31-2009, 06:34 PM

You might get a few bottle of fuel injection cleaner to run through several tanks of gas. Don't run this stuff stright as it might burn out a pistion.

You will need a new air cleaner. I am basing this on a fellow I knew that did this with a carbed Ford and his air cleaner just clogged right up. You might check yours before you replace it, but it will be something to check.

Pull your plugs and clean them. I would not replace them. Just clean them with some carb cleaner as they will likely be sooted up. Let them dry out good before you put them back in. Pull one and if it looks good then it will likely be OK to assume the rest are OK, too.

Let us know how it goes.

GaryF · #5 10-31-2009, 06:41 PM

Thanks for your responses, I'll do what you've suggested and hopefully get it running again on Monday its a relief to know I've not killed it. All the 35 years old parts in this car that have never let me down and its the "intelligent" mushy human in control that screws up.

t walgamuth · #6 10-31-2009, 06:52 PM

I cannot imagine how it would affect the air cleaner.

My old 67 jeep with the buick v6 would run on diesel! You had to pull the choke half way out though and it ran roughly and smoked like a bandit!

I filled it up with gasoline and ran it down and then again and it was not harmed. I have heard that diesel will damage the injectors on a gasser but truthfully I am sceptical about that.

junqueyardjim · #7 10-31-2009, 07:20 PM

When we were kids during WWII, there were a lot of old cars around, since nobody could get gas. It didn't take us kids too long to figure out they would run on kerosene. Diesel as a motor fuel had not reached us in western Iowa, but everyone had kerosene stoves and heaters, and I don't think it was rationed. We always had the most fun and best rides getting old 32 to 35 Plymouths and Dodges to run on it. They would get so hot and smoke so bad, but they would keep on chugging. Oh ya, you had to have the choke pulled way out to keep them running.

Tomguy · #8 11-01-2009, 07:08 AM

Thankfully, you have D-Jet and no mechanical injection pump built for gasoline that may break, rupture or otherwise fail on diesel. The diesel injection pumps are much heavier duty!

Drain it all out, replace the fuel filter, pull the plugs and crank the engine with them out. You may want to put some rags next to the plug holes so diesel doesn't shoot out everywhere. Then reinstall the plugs, fill it with gas, and it'll re-fire. It may smoke as the diesel burns out of the manifold, combustion chambers, valves and even exhaust.

Jengasan · #9 11-01-2009, 05:31 PM

don't sweat it mate, you won't have hurt it......wait til you do it to your expensive japanese sports bike with exotic ceramic lined cylinders and finely tuned EFI system etc etc...yep...I also qualify for said award

Good luck gettin the old girl back on her tyres.

J

JiveTurkey · #10 11-02-2009, 05:56 PM

This is one of the few times in life when you're actually glad to own a gasser with Bosch D-Jetronic.

Pooka · #11 11-03-2009, 11:45 AM

One more weird comment on all of this. Well, not really this; just a weird comment.

When my mechanic friend was dealing with cleaning the diesel from his system, his 1981 carbed Ford Fairmont, he was just making it up as he went since there was really no manual to go to for instructions. One thing he tried was just running it out of the system after draining the tank and filling it with gasoline.

It still coughed and sputtered because he had not yet changed the plugs so he started hitting the carb with started spray which made it run smooth.

It also made it run so hot the cat converter started to glow bright red. It did burn the carbon off the plugs, though.

Just a word of warning to others that each one of these repairs is unique. The good news is that he repaired something like 50 or 60 cars and all of them ran great after he cleaned them up, so it is far from the end of the world.

GaryF · #12 11-05-2009, 03:29 PM

Hi Guys,

Finally pumped the last of the diesel out and put 30 litres of petrol(gas) in....after carefully verifying it was the correct fuel.
I had planned to replace the fuel filter and replace the plugs before attempting to start but my wife's nagging about the car blocking the drive and the bad weather here encouraged me to just try and start it. After about 10 attempts when it would run for a few seconds and then die again it idled nicely and a quick drive around the block was spot on with all 8 cylinders firing perfectly.
I'll refresh the above parts before driving again but happy that I have a useable car again.
Thanks again for your advice/help,
Gary