How to clean the crud in the combustion chamber

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SpeedyG75VW

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I've noticed in all my OPE engines, I have varying levels of crud in the spark plug hole. I currently use ethenol free gas but had previously ran regular gas with fuel stabilizer. All my OPE engines run fine but sometimes I have to take the spark plug out to clean because of carbon buildup. Otherwise it would be extremely hard to start. I've used Techron or Gumout All-in-One every time I refill the gas tanks so I'm a little surprised at the buildup.

Any ideas?
 
Originally Posted By: BrocLuno
If you have carbon build up, the jetting is wrong and it's running rich ...


which, interestingly could get better with a switch back to E10 gas.

So many people drill the jets out hoping for "more power", it doesn't work that way. If you live at a high altitude you may need to jet down.
 
Last edited:
Water. Get the engine hot and slowly introduce water (spray mist bottle, quick bottle) through the intake until it starts to bog. Go easy. Let off, let it regain full speed again, and immediately reintroduce water again until it begins to bog down. Keep repeating until you run a quart of water through it.
 
Originally Posted By: Phishin
Water. Get the engine hot and slowly introduce water (spray mist bottle, quick bottle) through the intake until it starts to bog. Go easy. Let off, let it regain full speed again, and immediately reintroduce water again until it begins to bog down. Keep repeating until you run a quart of water through it.


I've heard of this, essentially you're steam cleaning the inside of the engine. Although I've put thousands of hours on OPE without doing this, but if it makes you feel better I guess go for it. personally I think it's all a placebo.
 
On L-head Briggs & Stratton engines, I take the valves out and then go in there with a miniature wire cup brush and WD-40 to clean out the intake and exhaust ports. On the combustion chamber, I pull the head off and clean it the same way using a miniature wire cup brush and WD-40. The solvent in the WD-40 combined with the wire cup brush makes a black carbon soup as the brush is turning. Reminds me of stripping wax with a floor buffer machine.
 
Does this actually work? Does it clean real deposits?
Originally Posted By: Phishin
Water. Get the engine hot and slowly introduce water (spray mist bottle, quick bottle) through the intake until it starts to bog. Go easy. Let off, let it regain full speed again, and immediately reintroduce water again until it begins to bog down. Keep repeating until you run a quart of water through it.
 
Water does work well, but you have to be careful not to spray too much. The fuel going in is a fine mist and compresses during the compression stroke. Water won't compress as much and could hydro lock the engine. One short spray as fine a mist as your can, and let the engine regain speed between sprays. Maybe 10-12 sprays then check your progress after the engine cools.

L8R,
Matt
 
Originally Posted By: CT8
If there isn't a problem don't cause one.


This.
 
Often carbon deposits are self limiting and not detrimental to performance or longevity. It's rare that an engine will build up carbon to thicker and thicker levels until mechanical interference results.

In addition, carbon has a small insulation effect. This tends to slow heat transfer, a good thing indeed.
 
Originally Posted By: lars11
Does this actually work? Does it clean real deposits?
Originally Posted By: Phishin
Water. Get the engine hot and slowly introduce water (spray mist bottle, quick bottle) through the intake until it starts to bog. Go easy. Let off, let it regain full speed again, and immediately reintroduce water again until it begins to bog down. Keep repeating until you run a quart of water through it.


Yep. The truck in my signature get this treatment twice a year (but with a 350 small block, I just use the nozzle on my garden hose).

My truck burns a lot of oil and once it starts pinging, and running rough, this fixes it every time. Yes, it works.
 
Originally Posted By: Phishin
Water. Get the engine hot and slowly introduce water (spray mist bottle, quick bottle) through the intake until it starts to bog. Go easy. Let off, let it regain full speed again, and immediately reintroduce water again until it begins to bog down. Keep repeating until you run a quart of water through it.


Does it work on 2-strokes?
 
Originally Posted By: Cujet
Often carbon deposits are self limiting and not detrimental to performance or longevity. It's rare that an engine will build up carbon to thicker and thicker levels until mechanical interference results.

In addition, carbon has a small insulation effect. This tends to slow heat transfer, a good thing indeed.

Carbon depostis can "glow" causing pre-ignition, leading to pinging.
 
Originally Posted By: lars11
Does this actually work? Does it clean real deposits?
Originally Posted By: Phishin
Water. Get the engine hot and slowly introduce water (spray mist bottle, quick bottle) through the intake until it starts to bog. Go easy. Let off, let it regain full speed again, and immediately reintroduce water again until it begins to bog down. Keep repeating until you run a quart of water through it.



the water meth guys have spotless engines because of it.
 
Originally Posted By: motor_oil_madman
Originally Posted By: Phishin
Water. Get the engine hot and slowly introduce water (spray mist bottle, quick bottle) through the intake until it starts to bog. Go easy. Let off, let it regain full speed again, and immediately reintroduce water again until it begins to bog down. Keep repeating until you run a quart of water through it.


I've heard of this, essentially you're steam cleaning the inside of the engine. Although I've put thousands of hours on OPE without doing this, but if it makes you feel better I guess go for it. personally I think it's all a placebo.


We had one member who would POUR water down the intake of his mother's trailblazer. To the point it milkshaked the oil
 
GM used to sell a fogging spray for this if water costs too much where you live :). If the buildup is not burning oil I would get to the root of that problem rather than the symptom. A bad O2 sensor can drive your mix rich. If the mix is right your plugs should be light brown otherwise something else is going on.
 
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