Oh s*%&... there is gasoline in the diesel engine!



I filled up my 2000 Mercedes Bens diesel jeep with gasoline. The jeep died on me and the mechanic says the engine is ruined. It is going to cost a fortune to transplant a new engine. Is the shop taking me for a ride here? Also, if there is no other way but to put in a new engine, can use a diesel engine from a different 4x4, not a new Mercedes Benz engine? Please advise.


I’m a little confused, I don’t believe the diesel powered Jeep Liberty CRD was sold in the U.S. until 2005. Also, that engine is not manufactured by benz, as far as I know the jeep didn’t get a benz engine until 2007.

Do you know the extent of the damage and that the engine is not reparable? Have you looked for used engines, hopefully you could get it back on the road for a couple $1000.


Yes it can destroy the engine. It does depend. You did not say where you took it, I would advise a local independent mechanic with experience with diesels and that model if possible.


I’d drain the tank completely, put a few gallons of diesel in there, maybe find a way to purge the system of the residual gas in the pump, lines, injectors, etc. and then try to start it again. If you destroyed the engine already it’s not going to get better, but it would be crazy to replace it or rebuild it without trying to see if it will run again.


I think he means one of those enormous Unimog things.


They were not available in the U.S. in 2000 either. I suspect he typed the incorrect year.


Agreed. Your engine might be OK after the gasoline is removed. I have not heard of gasoline ruining a diesel engine. My old VW diesel can tolerate 30% regular gasoline for unjelling as needed in winter.


Unfortunately gasoline has damaged more than a few diesel engines, hopefully it’s repairable. Early (indirect injection) engines recommended mixing some gasoline in very cold temperatures, that is much different than burning straight gasoline.


Well, the original poster may not even be in the United States. My (wild) guess would be he’s talking about a diesel G-Wagen (the name is short for Gelandewagen, or Cross-Country Vehicle) that are somewhat common in Europe.
We really need more information.
To say “The engine is ruined” is not a very technical description. As stated by others, have they tried draining the tank and fuel lines and changing the fuel filters? It is possible to do a lot of harm if you drove quite a distance with the wrong fuel. And it does sound like it was driven until it died, so…

I don’t know how you can put the wrong fuel in a car,drive it until it dies, and then say the mechanic is taking you for a ride…I get so tired of seeing the things people do to their vehicles, and then blame the mechanic for the high cost of repairs.
(Off soapbox)

It would be cost prohibitive to try and put another brand of diesel engine in. I’d try and find a used engine at a wrecking yard.



It’s possible he is talking about a euro g-wagon, but I didn’t think “jeep” was a generic term for a 4WD vehicle in europe and there are very few late model euro g-wagons in the U.S (I guess he could be in canada). If so, that may be an expensive mistake.

Many folks seem to think the jeep CDRs all had benz engines. If it is a CDR, there’s a better chance of finding a good engine in a wreck. I agree that using another make of engine is not practical.

I also agree that he needs to verify if the engine is really toast from a qualified shop.


There is the question of octane/cetane here… It would seem that a diesel would not function on gasoline as it would not ignite easily without spark. What exactly was damaged by the ingestion of gasoline?


The problem is that gasoline will ignite too easily and burn too quickly in a diesel engine. Imagine how much pre-ignition you would have in a gasoline engine with a 20:1 compression ratio (instead of the usual 8:1 ratio). You cannot compare cetane and octane values, they are completely different (actually they are opposites).

Diesel engines control their “timing” by when the fuel is injected (usually about 20 degrees BTDC). Diesel fuel burns very slowly; the combustion process starts before TDC and continues throughout the power stroke. Gasoline burns much more quickly and can result in significant pre-ignition in a diesel engine (bent roods, etc.), much worse than running a high compression gasoline engine (10:1 compression) on low octane fuel.


Thank you for all of your assistance and prompt response to my car problem. Many of you asked about the exact make of the car, it’s a 2000 Mercedes Bens ML 270 CDI.

All of your responses have been very thoughtful and insightful and a few of you even figured out that the car is not in USA. It’s actually physically in Iceland right now.

If you have any additional comments, I look forward to seeing them and will be checking back often.

Kind regards,
The car talk fan


That makes more sense. Do you know the actual extent of the damage, and that the engine is not reparable? I don’t know the exact replacement cost of a new CDI engine, but it will not be cheap.

I have no idea how common CDIs are in Iceland, but I still think your best will be to look for a used CDI engine from a wreck. I guess you could re-power it with a gasoline engine, but that sounds like a lot of work/money too.


I’m sticking with my earlier reply. How long could you drive on pure gas? Not at all in my opinion. So maybe that pure gas mixed with the diesel that was already in the tank. It just seems crazy to get ready to scrap the engine without even trying to flush out the lines and refill it with diesel.


How long could you drive on pure gas? Not at all in my opinion.

Unfortunately, I know one person whose daughter proved a diesel benz will run on gasoline right up to the point where it stops running, permanently. Why do you think a diesel engine will not start and run on gasoline (for a little while)? Have you ever seen a gasoline engine “diesel” after it’s turned off? Imagine that process with twice the compression.

gasoline + air + compression = BOOM

I do agree that the OP should be very sure the engine is not salvageable before writing a very large check for a new engine. Unfortunately, it’s not going to be a simple matter of draining out the gasoline and starting it.