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Pete White

Diesel In The Oil Sump!

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Diesel is somehow leaking into the sump, causing over revving and thinning the Oil. It's an '01 D-4D, I paid £1400 on ebay. What can it be? What's it likely to cost? Any ideas?

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hi matey

what have you paid for ????? It is very interresting.

You have one of the following issues:

- poor injection (too much leaks (pour diesel);

- leak thru fuel injector assembled parts;

- leak thru poor joint connection between HP fuel injection pipe and injector body thread;

- leak thru return line joining each injector.

It is normally happened due to vibration.

You are free to open valves cover to investigate it. It's understood you have to change an Oil in the sump.

regards / Igor

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I would have thought that the most likely route would be past your piston rings on the compression stroke. With a car of this age that would be my first guess but, in this case I would hope to be wrong.

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Big thanks for your thoughts guys. Worried about the cost of a repair, I plucked up the courage to investigate myself. Although I'm waiting for a part, I'm all sorted!!!! It is a relatively easy fix. After removing the plastic top cover, I removed the 4 injector pipes then the rocker cover. I then reconnected the injector pipes. I got my wife to turn the engine over on the key and hey presto...I spotted the fuel leak. It was the wibbly-wobbly steel return pipe that connects the returning fuel from the 4 injectors. It was split at the junction of injector No1.

Looking at all the components and the layout, I cannot see any other way that diesel could get into the sump. For fuel to leak past pistons, the engine would have to be in a pretty poor state, probably wouldn't even start and you surely wouldn't get a gallon of fuel in the sump after only doing 100 miles, which is my case.

However as pleased as I am at finding the fault, the down side was when I looked at the return pipe, I thought it looked to be about a tenner's worth, but would probably be £25 from Toyota. The reality was....£112 !!!!!

So now you know. I hope this may be of use in the future.

Cheers, Pete

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Nice to hear of a good result Pete, it certainly looks as though that was the prob, fingers crossed :clap:

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Yep there's no way a gallon would go past the piston rings thats for sure! So is the return pipe inside the rocker cover hence the leak into your Oil?

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Yep..the pipe is under the rocker cover. In my case the return pipe had been badly fitted bending it into the path of the first cam on the shaft which scuffed a hole in it. It is my belief that a previous owner must have had this problem (fuel in the sump) did the repair (badly) and probably thought it must be some other fault and got rid of it. I bought the car from a small time dealer on ebay.

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So, repairs done and the car's turned out to be a bit of a bargain. Winner!

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Don't know about a bargain...it's cost me £1500 for an '01 Avensis D-4D. Although aside from the now fixed fault, it is is pretty good nick. Everything works, good and clean bodywork and interior and plenty of impressive power.

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