De-carboning engine

[Donald M.]

I have heard of using water to de-carbon combustion chambers. What is the correct procedure? Does this also clean the plugs somewhat? Thanks!

[Chuck S.]

Roy Braatz?!...Yer Up!...Inquiring Mind Here!

(And, Don, if you don't do this...Don't say anything, OK? Roy, like the rest of us old geezers, gets real sensitive when young whippersnappers don't take his advice! BTW, Roy has covered this subject just recently...engraved in the archives...Try searching on "water carbon engine", click ALL TERMS.)

[Clem Z.]

Re: De-carboning engine

GM sells avery good product for top engine cleaning,part # 1052626 and follow the instructions on the can

[Donald M.]

Re: De-carboning engine

Chuck, Clem, thanks for the tips on using water to clean out carbon. I found most of what I need to know in the archives. But, I have one last question: will it be necessary to change the oil after I de-carbon the engine? How much carbon wil get to the oil, if any?
Don

[John G.]

Re: De-carboning engine

Supposedly, the story goes, some mechanics used to do what was called an 'STP valve job'. This was in the days of leaded gas and higher compression 60's engines. The 'valve job' consisted of an engine compression check to troubleshoot a rough running engine and detonation problem. If found to be too high a can of STP was poured down the carb into the running engine to loosen up carbon deposits in order to achieve a more level compression between cylinders. The story went on to say that some wiped off the heads to make it appear that they had been pulled and a 'real' valve job had been performed - in order to dupe the customer.

An 'urban legend', perhaps .. ? .. I really don't know. I knew of several guys who tried it, though. Boy..............talk about SMOKE .. ! ..
John

[Roy B.]

Re: De-carboning engine " None oil OK" *NM*

[Tony Alison]

Re: De-carboning engine

Thier is also a product called Seafoam. You can buy it at most napa stores and O'Riely auto parts. You pour it in a vacumn hose ad shut the engine down and let it sit for a while. The instructions are on the can. You can also mix it in the gas. It's a great product.

[Chuck S.]

Re: De-carboning engine

Hey, John, I've done that STP thing before...If an engine can eat that goop it should have no problem at all with a little water going down the carb. It looked like one of those old DDT mosquito fogging machines back behind. The only trouble was...that STP "valve job" didn't improve that flat head Ford I owned...It took a Chevy small block (in a new Chevy) to fix that problem.

[Chuck S.]

Re: De-carboning engine

Don, my only concern about doing this would be water washing the lubrication off the cylinder walls and valve stems, so I would not continue this process any longer than absolutely necessary.

If you plan to do this, I would plan it just before a scheduled oil change. I doubt there will be enough carbon in your oil to be a concern (filters work really well on particulates anyway), but there may be some water from blowby. I wouldn't want it circulating around posing as lubricating oil and plugging up the oil filter, so an oil change afterward would be on the safe side.

I know this can be done, has been done, and can be effective, but there's no point tempting fate IMO. With all due respect to Roy (He's forgotten more than I ever knew about cars), but I would probably would start with Clem's suggestion and use GM's top cylinder cleaner...it's petroleum based and will provide lubrication instead of depleting it.

[Doug Flaten]

Re: DDT

As a kid in New Orleans, we used to have great fun riding our bikes in the fog behind the mosquito sprayers. I am not sure they were using DDT but it was before it was banned. Looking back it was not our brightest moment

[Duke W.]

Re: DDT

I've been watching this thread with some amusement. I'm not sure that "carbon buildup" is a problem and may even help. Case in point, my Cosworth Vega.

It never did get more than about 600 miles per quart of oil from new Being as how it's only a two-liter four, that's A LOT of oil passing through the engine. Over it's 70K mile life it got a lot of "Italian tuneups" including 4-5K miles of racetrack hot laps. It always ran strong and could pass the emissions limits for a brand new car.

Borescope inspection showed plenty of carbon buildup including the tops of the inlet valves and white oil ash deposits on the exhaust valves. I theorize that carbon buildup on the tops of the inlet valves may actually improve air flow by creating a better approach to the valve seats, and the reason that carbon builds up on the top of the inlets is that it's basically "dead air space" that is not scrubbed by high speed air flow even though the injectors direct their stream of fuel right at the tops of the valves.

So when the oil consumption got down to 100 miles per quart a few years ago I decide it's time to refresh the head - cleaned all the deposits off the head, pistons, and valves. did a little pocket porting, replaced the guides with the latest nickel bronze parts and new modern valve seals. I just lapped in the valves - didn't grind the valves or seats. Oil consumption is now a quart every 4-5K miles, but's it's tough to measure because I don't accumulate more than about 1K miles between annual oil changes.

The engine does run better (123 RWHP @ 7000, 80 percent torque bandwidth 2000-7200)), but I attribute that to reindexing the cams, which I did as part of the job. If the oil consumption (and occasional blue smoke) hadn't gotten so bad I would have never done the work because the deposit buildup from the oil consumption didn't seem to affect performance. It was primarily a "cosmetic" issue.

Duke

[Dick W.]

Re: De-carboning engine

I do not think that the water would be a problem washing the lube off the valve stems and cylinder walls. Iff'n you are old enough think back about the water injection kit that Edlebrock and others sold. I threw one out in the scrap pile about 3-4 years ago. Used them for water and alcohol injection to reduce? detonation.

[Clem Z.]

water injection causing wear

i tried it years ago on supercharged boat engines and it cause excess top ring groove wear. i would guess it was cause by the water washing away the oil that lubed the top ring groove

[Chuck S.]

Re: water injection causing wear

Dick, a lot of fact has been determined empirically...that is, people have tried something and they were successful. However, water in sufficient volume WILL compromise the lubricating properties of oil (an empirical fact ).

I would bet that way back there, Edelbrock had an engineer that discovered exactly how much water you could put into an engine intake before he had a reeely big mess to clean up...had to know exactly how big to make the orifice(s) doncha' know. I am simply saying that, I might be inclined to try the least aggressive approach first.

Clem, I can speculate that in addition to losing lubrication in the top groove that could result in wear, there may also have been liquid water trapped in/around the ring and groove. When the cylinder fired, that water was instantaneously turned to steam. The high velocity from the expanding steam may actually have eroded the groove.

[Chuck S.]

Re: DDT

Duke, I can't disagree with your analysis...in fact, I have wondered how one even knows one has "carbon buildup" without a borescope inspection...seat-of-the-pants dynometer? So, you're saying carbon is just a light-weight material that bonds to the valve head and fills a dead space, thereby creating a more aerodynamic shape to the valve head? (I suppose manufacturers couldn't make "domed" valves out of alloy steel...too heavy?)