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MG MGB Technical - cleaning engine: diesel-fuel as engine-oil

Hi,

Somewhere I read a method of cleaning the internals of an (older) engine by running it some time
on diesel-fuel or a diesel-fuel/engine oil mix replacing the normal engine oil.

Can anybody tell me more about this?
Did anyone do it? Results?

rob
NL
rob

I have never haerd that one before. Maybe I might consider it with proper diesel ie gas oil but not with the modern low sulphur 'diesel' which is much nearer to Kerosene which has much lower lubricity. Why not just use a very high detergent low viscosity lube oil and not leave it in very long?

Maurice
M Blakey

Rob, never heard of using diesel, but I have heard quite a few folks swear by automatic transmission fluid. Never have tried it myself, so I can't give any positive results!
Ken Lessig

Why not use 'flushing oil', which is made for the job. In UK it is very easy to get at motor shops.

Neil
Neil

Back in 1974 (I think) it was necessary to do an engine tear down on my '69 MGBGT due to a warped head. With the help of a good friend, who also had an MG and was much more knowledgable than myself, we "flushed" the engine with diesel fuel by putting some into the crank case and running the engine for a couple minutes and then draining it out and filling back up with oil. This procedure did indeed, clean a lot of gunk out of the engine and from that experience I never suffered any noticable negative consequences. I've thought about what we did and I have to admit that I probably would not do it again. I must believe there are better ways to "clean" the innards. Help this helps.

Cheers - Dennis - Sacramento
Dennis Rainey

Whenever my Dad would buy a used car, he'd fill it with Shaler Rislone, run it around the block, drain it and then fill with regular motor oil. I believe that's the "flushing oil" spoken about. I just checked their website, and they now have stuff with the same name, but now it's added to your regular oil.

I suspect that the recipe is pretty much the same as in my Dad's day, but then again, it may have changed into something else entirely. Anybody know for sure?

PS - the other "family secret" was using Coca-cola for flushing engine blocks and (I believe) cooling systems. This was something my uncle, who worked on engines his entire life, would do. Between the carbonation and the acid, apparently it would clean everything out. I'm still suspicious about the sugar, though.
John Z

Use Diet Coke then.
( * )

Yes, a diesel mix in the oil is a good flushing solution (commercial flushing additives contain it) - so is putting ATF into the oil.

Diesel poured into the plug holes is also a good way of freeing seized engines and dissolving carbon.
Chris Betson

My past has included using a cup of diesel. I used to pour it slowly (drizzle) into the carb while running. The result was white smoke while it was burning. Afterward, the engine seemed to run better and I only did it before changing the oil. This can't be done with the side drafts. I did it on old VWs and older American cars. Always with good results.

kids1

ATF has no detergent so it won't clean, I used to believe that it cleaned until one of the engineers when I was with Pennzoil ran his car on straight ATF for a few months just to prove the point.
Lloyd
Lloyd Gregory

Err, I wouldn't use diesel as flushing oil, partly 'cos it just wouldn't cross my mind, and partly due to bad experience of a colleague of mine. I have to say this is not a first hand account, but I will tell the tale as reported to me. My colleague used diesel to flush a Ford Kent Cross-flow 4 cylinder, re-filled with nice fresh oil, and a week later the big-ends and mains cried enough. He said at the strip down all the bearings smelt of diesel and apparently had failed due to lack of oil/overheating. It seems for what ever reason that the diesel had formed a film over the bearing surface preventing oil from coating them, which caused them to fail. As I say, that is how it was reported to me, but thought I'd share it on this thread.

Phil.
Phil Hill

Diesel in the sparkplug holes dissolves carbon?? Really?? How would you go about it, remove plugs, put some in, and turn engine on the starter without HT, then leave it for a few hours?

This might be interesting for my Non MGB...(maestro)..sorry, it just jumped off the page at me..:)
karl

Diesel oil will ruin the engine oil's lubricity so don't drive anywhere with it in the crankcase , you should do minimum of _two_ oil & filter changes to get all the diesel out or you'll blow a bearing like the Ford mentioned above . I have used it in the past but no more as I've seen too many customers blow engines within two weeks of flushing with diesel , it does indeed clean the old sludge right out but Rislone or doing a synthetic oil change will do the same thing .

_Always_ change the filter after running any
flushing agent !.

A petrochemical engineer I know tells me ATF is exteremely detergent , I have used it to clean sludge out of several of my vintage cars and also motos with cetrifigal oil filters , it fills the centrifuge _full_ of crap every time so I know it's detergent .
I only do this _once_ when I first add the vehicle to my fleet .

To clean carbon off the piston crowns , warm the engine up _fully_ then hold the throttle open to about 3,000 RPM and _slowly_ dribble diesel or better yet plain water in the carby intake , you _must_not_ pour in a bunch of liquid as the engine can and will hydro-lock , bending rods and / or breaking pistons . I use a spray bottle with water now , works a treat on side draught carbies and you _cannot_ possibly damage anything by adding too much liquid .
-Nate
NSH

Can't help with cleaning the bottom end, but to clean the top end the best I've found is a commercial product designed to do just that. It's called 44k and made by BG Products. So far as I know it's only available to the trades so you'll need to get it through a dealership or a savy independant shop. Expensive too, ~$20 a can. But it does the trick! At a shop where I worked we had troubles with poor idling/running in BMWs that could be cured by running a can of 44k through. The problem was caused by carbon buildup on the backs of the intake valves -- they're directly in the path of the injector spray, and the carbon would absorb and release the fuel and ruin the idle. The 44k took the carbon right off. I now use a can in every car when I first add it to the fleet and about every 15,000 miles thereafter. I might add that I'm in no way connected to BG Products other than as a satisfied customer.

Another good product (so I've heard) is GM's Top Engine Cleaner. Never used it, but I think it's a dribble-into-the-carb type of thing....
Rob Edwards

I seem to remember from school chemistry that nothing dissolves carbon - it is insoluble.

Am I right?

Neil
Neil

A buddy at work told me this story:
Back in the fifties, about a decade and a half after the WWII pretty much everything was still government regulated in Finland, especially fuel and oil for cars. Taxi drivers had it a little easier, but getting oil was sometimes difficult. Well, one day a taxi driver/owner noticed a barrel behind a deserted barn. He goes to investigate even though it is winter and temperature is way below freeze. He is delighted to find something that looked like motor oil. So he takes his empty fuel can and steals enough oil for his next oil change. He changes the oil and after a few days checks the dipstick, only to find that it is dry. He goes back to the barrel, refills his can and pours enough oil so that the oil level in his Plymouth looks OK. Later that day he goes and finds the oil level low again, and fills it with same stuff. This goes on for a week, and by then the barrel is half empty. The driver decides to take the car to the shop, since he has found no apparent leaks and cannot figure out where the oil disappears. The shop people remove the oil pan and find the lower part of the engine shiny and clean, like the car had just rolled out of the assembly line, and never had had oil in it, or run. Well, to make a short story long, when they brought the reserve fuel cannister full of "oil" in the shop that was warm also in winter, it turned out that the taxi driver had used diesel fuel as motor oil all along. The story tells that after a refill with real motor oil the engine would run well for many years until that big old Plymouth was crushed during the oil crisis.

The guy that told me this story was wondering if he could try this diesel fuel trick on his Range Rover, that may have some sludge in the oil channels. I recommended to put at least 50% real motor oil... The diesel fuel nowadays is also propably lighter than it used to be way back when.
Kari Sillanpaa

Thanks for that many answers on my asking!

Diesel fuels seems to be not unproblematic for cleaning a running engine...

The special formulated 'flushing oil': does this -possibly- have adverse effects to rubbers and gaskets too, or can it be handled as *completely safe*???

Maybe cleaning can only be done by taking the engine apart and buffing the parts ;-))

rob
NL
rob

I remember a product called Tuneup made by Cassite. It could be poured into the gas tank, the oil or slowly poured into the carb. If used in the oil, the oil should be changed shortly after. It looked like atf when it came out of the can.
kids1

For additional information on Casite and Hastings chemicals see:
http://www.hastingsmfg.com/casite_chemicals.htm
Kids1; I remember the product very well, it was around 1947 a friend and I went to the
local Western Auto store and bought some Casite to Pour through the carb of his 40
Ford. It filled the area with smoke. Don't know if it helped the car but it got some
attention of others near by. Clifton
Clifton Gordon

Neil,

Whether is dissolves the carbon itself or the gummy residue that sticks the carbon particles together, but if you leave a carbon caked valve or piston in a bath of petrol or cellulose thinners ( better) then the hard carbon can be rubbed off quite easily.
Chris Betson

This thread was discussed between 18/04/2002 and 20/04/2002

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