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Car Forum / Driving, Maintenance, Tuning / General Car Topics / December 2005Help ASAP Please (Gas in diesel engine)
Thanks in advance for any help you can offer. I have an 87 diesel jetta (and have had it for years) and somehow last night filled it right up (was almost completely empty) with regular unleaded gas. I then drive a good 10KM before it started chugging and I realized what I had done. Car is now parked by a local service station but I am hoping someone can advise me how best to rectify this situation. The car is old so I am not looking to spend a fortune. It still runs great so I am hoping I have not screwed it up for good. I can't afford a big bill. What a crappy time of year for this to happen. I am an idiot. Thanks again for the help. <mimmikor@yahoo.com> wrote in message > The car is old so I am not looking to spend a fortune. It still runs > great so I am hoping I have not screwed it up for good. I can't afford > a big bill. What a crappy time of year for this to happen. I am an > idiot. > > Thanks again for the help. Siphon out the gasoline into an approved container. Refill with diesel. Drive away. The gasoline that has already been cycled through the engine and the rest of the system won't do any harm ? ><mimmikor@yahoo.com> wrote in message >> The car is old so I am not looking to spend a fortune. It still runs [quoted text clipped - 6 lines] >Siphon out the gasoline into an approved container. Refill with diesel. >Drive away. > The gasoline that has already been cycled through the engine and the rest of the system won't do any > harm ? It has already gone into the system, and I wouldn't worry about it at this point. Get the gas out and put diesel in. Fire her up, let the gasoline flush out, and see what you get. Dont stress the engine until you get diesel to the engine. You could disconnect the fuel line up front and flush it out, but it is a lot of work for little or no payback. >>The gasoline that has already been cycled through the engine and the rest > [quoted text clipped - 12 lines] > lot of work for little > or no payback. I missed the first post, so I don't know what kind of diesel engine this is. If its a typical older injection-pump type, or even a unit-injection type then things are a lot less critical than if its a common-rail type. Diesels of all sorts depend on the diesel fuel for lubrication of pumps and injection components, but common-rail diesels are PARTICULARLY sensitive to lack of lubricity and can be damaged by smaller concentrations of gasoline in the fuel than conventional diesels. There was another thread recently that specifically involved a common-rail diesel vehicle that had had a few gallons of gasoline diluted into a half-full tank and then topped off with diesel (about 20% gasoline, IIRC). The general consensus was that it would *probably* be fine, but a lot of people were curious as to how the high-pressure pump would hold up over the next few years years. The other thing that matters is how severe the gasoline dilution was. If it was only a couple of gallons into many gallons of diesel, its not nearly as big a risk as a full tank of gasoline into an almost-empty diesel tank would be. If you choose to just drain the tank and not the whole system, adding a quart of so of oil to the diesel won't hurt and might help Thanks for the info. This was an 87 VW Jetta (not sure if that is injection-pump or common-rail). It was also a full tank of gas into an almost completely empty tank of diesel so the mixture was >95% gas. > Thanks for the info. This was an 87 VW Jetta (not sure if that is > injection-pump or common-rail). It was also a full tank of gas into an > almost completely empty tank of diesel so the mixture was >95% gas. Well it aint no common rail! Thats a pretty high concentration of gasoline. Even though its not a CR engine, I'd still get rid of as much gasoline as possible before firing it up, including changing the filters. I might even pre-fill the filters with a diesel/oil mixture. > I missed the first post, so I don't know what kind of diesel engine this > is. If its a typical older injection-pump type, or even a unit-injection [quoted text clipped - 17 lines] > If you choose to just drain the tank and not the whole system, adding a > quart of so of oil to the diesel won't hurt and might help I think in this case the dilution was severe, but there is nothing he can do now. It is apparently an old car. If he leaves a few ounces of gasoline in the lines after draining the tank and refilling with diesel, I would expect no damage. Your comment about adding some compatible oil to the diesel would probably be a good idea.. I am of the opinion that adding a good two cycle oil might be better than a motor oil.. What do you think, Steve? > Your comment about adding some compatible oil to the diesel would probably > be a good idea.. I am of the opinion that adding a good two cycle oil might > be > better than a motor oil.. What do you think, Steve? That would've been my guess, or maybe Marvel oil, BUT the diesel gurus that weighed in on the other thread seemed to favor the same oil that the engine would use in its crankcase. Go figure. > there is nothing he can do now. It is apparently an old car. That would be the atrium and ventricle of the heart of the problem, wouldn't it? Any damage that could happen in 10 kilometers has already happened. The parts and labor involved in looking for internal damage might get you a good part of the way to an overhaul. And it's an old car, much though it hurts a person to finally lose a car that has been giving good service for a long time. My guess: Remove the gasoline (probably by hand-pumping it into gas cans) and use it in cars meant for it (mild diesel contamination won't hurt them usually). Change the filters, and drain the lines if that's reasonably easy. Idle for a while. Drive in a mild-mannered fashion, with your cell phone and auto-club card readily available, until you either build confidence that the engine has survived its ordeal or conclude that it is damaged and needs major work. If you're lucky, it'll be fine. If you're slightly less lucky, the fuel pump might have gotten some accelerated aging. If you're really unlucky, you get to decide what to do with an old car that has trashed pistons or con-rods. If you didn't romp on it too hard before noticing the problem and then nursed it carefully to a nearby garage, maybe you'll have one of the luckier cases. --Joe Just to offer a bit of science perspective, I thought that diesel fuel was used with diesel engines mostly because it is cheaper. Otherwise one could be injecting gasoline into the cylinders, and it would still burn up. The ignition is based on temperature, and not the spark. The only issue is that gasoline viscosity is lower than diesel fuel, and so some components may not be designed for that. Thus replacing gasoline with diesel fuel and burning the gasoline from the lines on idle could work just fine if the engine still works when diesel fuel starts to go into the cylinders. You can wash the tank quite effectively by removing gasoline, adding a bit of diesel fuel (1 gallon), removing that, etc. This way after a few washes the fuel in the tank will have very high fraction of diesel fuel which you could burn through, and then add a full tank of diesel. But this may be unnecessary. Let us know how things worked out! Mike > Just to offer a bit of science perspective, I thought that diesel fuel > was used with diesel engines mostly because it is cheaper. > > Otherwise one could be injecting gasoline into the cylinders, and it > would still burn up. The ignition is based on temperature, and not the > spark. Apparently direct injection of gasoline presents a bit of a different problem than injection of diesel. I have been of the impression, perhaps falsely, that since diesel uses compressive heating to fire the charge, the timing of the burn is heavily dependent on the properties of the fuel. If true, then the gasoline might ignite much advanced to what the diesel might do. That could be a problem. Lubrication of pumps, etc, which diesel fuel would provide would certainly not be the same for gasoline. We had an old diesel forklift at our warehouse Scotland. In the winters, which were bitterly cold, the previous crew had resorted to ether starting fluid to start the thing. A mechanic later told us that, once ether had been used, the combustion was so advanced that the crankshaft had actually been bent, making starting with diesel a problem. Truth or legend? Dont know. Maybe others here can comment. >>Just to offer a bit of science perspective, I thought that diesel fuel >>was used with diesel engines mostly because it is cheaper. [quoted text clipped - 11 lines] > then the gasoline might ignite much advanced to what the diesel > might do. That could be a problem. Thats almost what happens. Since fuel isn't injected until its ready to burn, you can't really get "pre ignition" in a diesel. What can happen is that the fuel doesn't light immediately, but accumulates briefly and then goes off all at once. The timing will actually be LATE, but the combustion will be more of a detonation than a burn and damage can result. Proper diesel combustion isn't a flame-front that sweeps across the cylinder like a spark-ignition engine, its closer to a torch flame on the tip of the injector during the injection cycle. "Torch" is misleading, since the injector is designed to create a fan flame rather than a torch-like pencil flame, but you get the picture. > We had an old diesel forklift at our warehouse Scotland. In the > winters, which were bitterly cold, the previous crew had resorted [quoted text clipped - 3 lines] > diesel a problem. Truth or legend? Dont know. Maybe others > here can comment. Its possible, but I'd expect something like a connecting rod to bend before the crank would. With starting fluid you are introducing a fuel into the intake air BEFORE the intake valve even closes (like with a spark-ignition engine) and therefore exceedingly advance-timed combustion *is* not only possible, but practically guaranteed in the higher-compression diesel engine. > Just to offer a bit of science perspective, I thought that diesel fuel > was used with diesel engines mostly because it is cheaper. [quoted text clipped - 5 lines] > The only issue is that gasoline viscosity is lower than diesel fuel, > and so some components may not be designed for that. That's ONE issue. There are others, the prime being that gasoline is a much poorer lubricant than diesel. But there are still others- whereas gasoline engines require gasoline that is resistant to self-ignition in order to avoid detonation, diesels need a fuel that WILL self-ignite immediately upon injection. If it doesn't, it accumulates in the cylinder and then detonates rather than burning smoothly, causing a phenomenon very similar to detonation in a gasoline engine. |
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