Flushing engine

[Diamondpilot]

My good friend has a 1999 or so 4 cylinder Dodge Stratus. It has 350,000 plus miles on it and he has not done one thing to the internals of the engine. It runs great, uses no oil, does not smoke, ect. He does 3,000 mile changes religiously.

I just bought a little used car with 101,000 miles on it and he told me at every oil change he adds a quart of diesel to the oil and lets it idle for 5 minutes then does his change along with the filter. He says he has always done this to all his equipment as it gets up in age, say 75,000 miles or so. He says he also does a more thorough flush every 15,000 miles by draining the oil and leaving on the filter. He then pours in a gallon of diesel and lets it idle for 5 minutes then drains it and changes the filter for a more complete flush.

What do you guys think? I have seen engine flush products at auto parts stores and when you look at the ingredients the main component is kerosene. I have no problem adding the quart to the oil prior to oil change to help clean the internals but running with diesel in place of the oil even for just 5 minutes at idle just scares the **** out of me.

Chris

 

[backdoor]

Long ago I was in the Army with a deisel mechanic from Alaska, he worked on fishing boat motors there. We were draftees, so naturally the Army put us to work doing stuff we knew nothing about. Anyway, he told me about doing the same thing to the fishing boats, just about like you spoke of, if I remember right. I would have to see this done several times to the same vehicle before I would do it to one of mine.

 

[crashz]

Considering the fact that fuel injection pumps fail due to ULSD, I'd be very hesitant to fill a crankcase with it and turn the key!

But - you are right, most engine flushes are a kerosene or light distillate base with very little else as an effective ingredient. The one thing I would caution you with is that the motor flushes move a lot of contaminates quickly and heavy sludge will only partially dissolve before getting caught in the flow. This leads to grit and sludge being moved around to sensitive areas like bearing surfaces and valve seals. Since your car has not had the flush treatment regularly, there is a possibility of 101K miles of accumulated sludge in the engine. A flush may loosen all that up and cause problems.

If I were you, I'd run short 3000 mile intervals with a diesel rated oil for the higher detergent/dispersant additves and see if you are getting a filthy black oil. Until it stays relativley clean, I wouldn't try to flush it.

 

[Eagleview]

I agree that if an engine has a lot of gunk in the sump and it is mobilised again , it will block the filter and cause the bypass valve to open . This will then allow unfiltered dirty oil to be pumped through out the engine . As for using straight Diesel , i would think it's very low viscosity would allow metal to metal contact at the big ends etc as the oil pressure would be under 20lb at idle . Also the new low Sulphur Diesel has ruined many an injector pump as it attacks the rubbers and "O" rings , i wonder what it would do to crankshaft seals etc ?

 

[Egon]

I knew a fellow that flushed his engine with diesel to clean it out. He had to replace the engine!

 

[Bird]

It's been 50 years since I did an engine flush with 4 quarts of oil and one quart of kerosene. It worked pretty well then, but the old car didn't even have an oil filter. And it's been about 30 years since a mechanic I trusted told me to add 2 quarts of ATF to a crankcase already full of oil, then start it and let it idle 5 minutes and drain it. That, too, worked to free up some sticking hydraulic lifters. But those were gasoline car engines, not diesel. I suppose the same thing would work on diesels, but no way I'd do it with the straight diesel or kerosene and no oil.

 

[Diamondpilot]

Thanks for all the responses. I just want to make it clear that my friends engine is gas in the Dodge Stratus and the engine I was considering doing this to is gas also.

I am not sure what I will do. I am changing the oil first thing in the morning. I may very well just add a quart to the oil, warm it up then drain it. I am not using ULSD. I have about 150 gallons of the old stuff still in my 300 gallon tank. It is off road, dyed red, that I get from my Co-Op.

Chris

 

[vsteel]

I personally wouldn't do that. That is something that was mostly done years and years ago. In 1950 half of the cars didn't have oil filters and lots that did were not full flow filters. The oil that went to the filter would drain back in the crank case.

The metallurgy that was in those old motors also didn't let them seal very well and they would get tons of carbon in the motor, along with dirt because the air filters were not so good, or they were running oil bath.

With current motors, current oil and filtration systems, engines don't get a tenth of the crap in them they used to. I think your friend is just lucky with his motor more than anything.

Just change the oil per recommendations and sleep easy.

 

[Skyco]

I wouldn't do it either....and if the guy selling the used car had told me he had been doing it I probably wouldn't have bought the car

 

[Egon]

I too can recall when transmission fluid was added to free up sticky lifters. Sometimes in the oil, sometimes in the gas.