1930's Cadillac "Carbon Burning"

[Str8-8-Dave]

So I bought a reproduction 1932-33 Cadillac/LaSalle service manual and in the engine section it discussed methods of de-carbonizing combustion chambers which in today's world, with today's fuels and emissions equipment would not be a topic of consideration.  On 8 cylinder flat head models the method is pretty straightforward, pull heads and scrape.  On V-12 and 16 cylinder models the manual recognizes the added complexity and labor required to dis-assemble and scrape these engines due to the fact they are overhead valve.  So Cadillac apparently came up with a clever work around called "carbon burning" which apparently is a procedure where all plugs are removed, asbestos pads are used to cover heat sensitive components and one cylinder at a time in firing order starting with the left bank is rotated into TDC firing position to assure both valves are closed to prevent high heat damage, and some kind of torch/burner arrangement is used to supply some kind of fuelgas and oxygen mixture to each combustion chamber to burn the carbon out of the cylinder without taking the head off. 

 

So here are my questions:

Has anyone ever done this or seen it done?

What kind of burning tool and fuelgas was used?

Since the valves are all closed and the piston is at TDC how is the hot gas and carbon exhausted from the burner rig?

What is the range of model years this procedure was used on?

 

When I was a kid working in the gas station a Cadillac shop mechanic used one of our service bays to bring an early 60's Cadillac that had been stored away for years back to life.  After repairing numerous mechanical accessories he started the car, let it warm for a few minutes, then lay over the top for the radiator with the air cleaner removed, revved the engine up to about 3000 rpm or so and slowly poured about a quart of water into the carburetor to decarbonize the engine with steam.  It made a racket and produced clouds of gray exhaust smoke but the engine survived and ran well afterwards.  I thought that was pretty wild, the carbon burning procedure seems like it is even more extreme.  

 

Edinmass- others- what does anyone know about the carbon burning procedure?

 

Dave

 

 

[Oldtech]

I have heard of the pouring water into the carb trick. never tried it. Otherwise...I dont know. 

[Bloo]

You got the burn started with an oxyacetylene torch somehow, and then fed the burning carbon some oxygen from the torch to keep it going. I sure wouldn't try that without some instructions.

 

Edited October 10, 2021 by Bloo (see edit history)

[Frank DuVal]

I've done the water trick many times. Do not let the engine stall! It will hydrolock....

 

Lots of stuff will keep burning with just oxygen supplied, like cast iron, steel. Hence a cutting torch. The gas is just used to start the puddle.

[Bloo]

Gus WIlson and the Model Garage, November 1926:

 

http://www.gus-stories.org/november_1926.htm

 

 

[Str8-8-Dave]

8 hours ago, Bloo said:

Gus WIlson and the Model Garage, November 1926:

Bloo- That article is a hoot!  According to that they were doing this procedure as early as 1926.  Wonder how long that went on before it was abandoned as a fire hazard...

[Rusty_OToole]

In a Popular Mechanics magazine from about 1950 there was an article about cleaning carbon out of cylinders with a kind of sandblaster that used rice instead of sand.

[DonMicheletti]

Another way used to clean carbon was to slowly "sift" rice hulls down the carb while the engine was running fast. I knew of a guy who killed his engine by feeding too fast. Always sounded like a bad idea to me.

[edinmass]

I think it’s more of an excuse to sell you service. Back in the 30’s, not all fuels were equal. Spraying water with a bottle into the intake easily cleans the engine. Using a torch in a V-16 Cadillac? Better make sure your valves are closed. Could also damage the head gasket. I would pass on this service.

[Buick35]

I've got an automobile engineering book from 1920 with a section on garage practices and it shows a chain attached to a drill motor which is supposed to remove carbon.I think it was fed down the spark plug hole.

[trini]

As far as I can see over the years there were hundreds of different snake oils sold as fixer ups.One thing I am sure of is from experience. My work mate had a 65,  8 Cylinder automatic ford. That vacuum thing on the transmission hooked to the carburetor, diaphram was broken. The car was loosing transmission oil . On discovery and  after correcting, he removed the valve cover. The inside of the cover and valve train was clean as a whistle. I poured transmission oil slowly into the carburetor of a running engine. Lot of exhaust smoke but it helped. I know some motorist who will pour a quart of transmission oil in a full tank of gas at every fill up. 

  Another trick is to squirt carburetor cleaner into the cylinders over a period of a few days and let it sit before starting. It is not a total solution but it helps. The point is to use something to soften the carbon and it can only be done while the engine is sitting, may be for a few days 

 

[JACK M]

OMC marine used to sell a tuner in a can that worked well.

Squirt it down the carb of a hot engine and let it sit over night.

My best customer for that stuff was a pot lot down the street.

Amazon still has it, Bombardier now.

Great stuff. I always keep a gallon around the shop.

[JFranklin]

On 10/9/2021 at 8:51 PM, Oldtech said:

I have heard of the pouring water into the carb trick. never tried it. Otherwise...I dont know. 

 

On 10/9/2021 at 9:40 PM, Frank DuVal said:

I've done the water trick many times. Do not let the engine stall! It will hydrolock....

 

 

Ok I learned of this in an automotive class in school. The trick is to run the cool engine at high idle and inject water mist at a rate that just allows the engine to run increasing a bit until a stall. He said to leave it set overnight and start it the next morning. The teacher warned that a mess would be exiting the tailpipe so it shouldn't be done in your clean garage. 

[Frank DuVal]

There is GM Top Engine cleaner 10-3015. But water is cheaper and does a great job.

 

I do remember reading those 20's Model Garages back in college. UVa has bound Popular Science back to issue 1. I also read them up till they ended in the early 70's. Lots of interesting ideas in those old stories.👍

Edited October 12, 2021 by Frank DuVal (see edit history)

[paulrhd29nz]

I was always told to use 1/2 trans oil and 1/2 water. Shake well in a squirt bottle. 
engine hot and squirt it down the carb but don’t let the engine stall. Pre warn you Neighbours and fire department cause the white smoke is unreal. If had good success doing this on old flat heads. It’s very important that when your done you pull the plugs and squirt some oil down the cylinders. The process above washes the cylinder walls down.