What causes excessive carbon build up opn top of piston and cylinder?
 

I was at a friends house looking at a engine he bought and we pulled the heads off and there was excessive carbon like I have on my engine.

A couple days later he said the machinist told him that was caused by bad valve guides.

I guess I am curious I assumed mine was from carburetor but I never had any exhaust color or fouled plugs.

What are the causes of high carbon build up.

Thanks

Greg

Slow driving. In my police days the patrol cars that got the **** ran out of them on the interstate went 200,000. The ones that creeped neighborhoods at 35 MPH were done at 40,000

High Carbon build up is caused by oil, Valve seals, Rings and PCV Systems usually.

Yep. Oil in the cyl causes more carbon than a rich mixture.

I always heard you could put some transmission fluid down carb while running to clean it all out, or i dunno someone told me water might even work. I put a camera in mine to have a look, some pistons look 1/2 clean, others have some build up. I think a leak down test will tell you what sort of shape each cylinder is in. Would be curious to see if trans fluid or water actually does improve the look of piston after. Now that we have cameras to check that "old time suggestion" out..Would be curious to see!

Fuel quality, quantity and engine operating temperature major factors in a mechanically sound engine.

It is well documented that Water Injection will remove carbon, but not so much evidence that just pouring a little water in the carb at idle will be effective.

WI is injecting water while the engine is under a load and creates steam, essentially steam cleaning the piston and combustion.chamber.

At idle, adding water might have some effect, but not to the degree that Water Injection will.

SeaFoam claims to remove carbon, but...

This guy has some cool videos. He's always testing oils and additives and stuff.
His vids move along pretty quickly too, so that's nice.
Here he tests atf vs. seafoam. he has several seafoam vids and has impressive results.
Project Farm
https://www.youtube.com/watch?v=wT0TTGO2CUY

The water trick works great, done it many times. Get your engine up to temp, fill a 2 liter bottle with water, give it about half throttle and slowly dump water into the carb.

Yup the water spritz works well, but it does not cure the root problem of excess oil consumption!
Oil in the air & fuel mixture present during the firing of the cylinder cuts drastically into any fuels octane rating and creates a spiral of issues starting with ping, then knock and then then Carbon fouled out plugs and oil that gets dirty fast.

Also not to mention the loss of power from however many cylinders that don't make the power tye should which then makes you lean into the rest of the cylinders even more and ware them out at a faster rate.

It can come from many sources, a thorough autopsy will reveal the cause/s..

What is the history/story on your engine?

It's his buddys motor, his is apart already.

I'm not a fan of sea foam and the other harsh chemicals.

What I've done for the last 20 years or so is mix my fuel with a little 2 cycle engine oil that has TCW3, for it's cleaning properties. 1 ounce per 5 gallons of fuel is all you need. It works very much like the Lucas fuel additive which isn't abrasive and lubricates as it cleans, but much cheaper.

The benefit is actually more than just cleaning but also adds a little bit of lubricity to the fuel that has long been gone since lead was removed. This helps to lubricate the valve seats, valves, and upper cylinders as well as having excellent cleaning ability.

I've torn engines down after using this method for years and have very little if any carbon buildup, and the valve seats have been in excellent shape as well with no issues of recession running unleaded fuels.

If there is one drawback it's remembering to add a little bit every time you fill the car up, but it's served me very well over the years.

Like others have said, if you have an engine with an oil consumption problem you're going to have pretty nasty looking cylinders, and if it's an oil control problem in the heads, the backs of the intake valves are usually caked and nasty. there really isn't a cure in a bottle for it.

I’ve not been on much for a while, link to his problem engine thread?
Curious😎