Decarbonizing pistons

[Volvohead]

Originally Posted By: slowdime
I had my spark plugs out recently because I was bored on my day off and figured I'd see how they were wearing after 40k miles of use. Plugs looked excellent but while they were out I figured I would peer down into the combustion chamber with a flashlight and see what I could see. I wasn't surprised to see carbon buildup on the tops of the pistons(what I could see through the plug hole at least.)
I've got a little bit of a rough idle, it isn't erratic, rpm stay the same, but it's enough to be noticeable. . . .
So what are your thoughts? Anybody done this themselves?


How about a treatment or two of Techron concentrate before turning to the shock treatments?

That will clean the entire fuel system and the combustion chamber.

A good Italian tune-up or two will speed up the process.

 

[Volvohead]

Originally Posted By: Miller88
Water injection used to be a thing


We used a lot of water injection in the '70s, but mainly for octane compensation. It worked.

Yeah, it will keep the chambers a little cleaner, too.

But those were more precise metering and misting systems that modulated to engine conditions, and not just sucking it wholesale through a vacuum hose.

I don't recommend it here unless the former approach is used.

 

[JDW]

Water Methanol Injection , Problem solved

 

[jk_636]

Originally Posted By: slowdime
Originally Posted By: joegreen
scotty kilmer is to fast for me. Being someone who knows a little sumn sumn about cars i feel like he leaves out valuable info.

I like the idea of disconnecting the vacuum gauge and sucking some water while driving down the highway.


He does tend to gloss over things quite quickly without much actual hands on stuff. Eric the car guy has excellent step by step info, but Scotty is hilarious IMO.

I think I'm going to give some water a shot through my vacuum gauge line on the freeway. I've got a good mental image of what the tops of the pistons look like now, I'll give it a try and see how it works out!


I love watching his (Scotty Kilmer's) videos. They are informative and crack me up. Water in a hot motor to decarbonize? There is NO way I would do that personally, but I have heard of people doing this in the past.

 

[antiqueshell]

If the OP is using Chevron as his regular fill on a regular basis he is getting all the cleaning he possibly could because of the PEA (Techron)contained in their fuel. Maybe add a bottle of full strength Techron for the most complete effect.

In any case your rough idle is doubtfully the result of carbon on the piston tops/crowns.

You might have old plugs, worn cap or rotor, vacuum leak (strong possibility) or a dirty MAF sensor or O2 sensor.

 

[slowdime]

Originally Posted By: Volvohead
How about a treatment or two of Techron concentrate before turning to the shock treatments?

That will clean the entire fuel system and the combustion chamber.

A good Italian tune-up or two will speed up the process.


I fill up almost always at chevron, but I suppose an extra bottle in a full tank wouldn't hurt. Also I've got a nice winding under-trafficked road with a long marginally steep grade I drive every day as part of my commute; usually every other drive down it I stomp on the gas the whole length of the road and keep it in 3rd at 50mph.


Originally Posted By: Volvohead
We used a lot of water injection in the '70s, but mainly for octane compensation. It worked.

Yeah, it will keep the chambers a little cleaner, too.

But those were more precise metering and misting systems that modulated to engine conditions, and not just sucking it wholesale through a vacuum hose.

I don't recommend it here unless the former approach is used.


So the method I mentioned earlier using a needle type fitting on the end of a vacuum hose wouldn't be conservative enough? I don't intend on letting it gulp down a ton of water by any means

Originally Posted By: antiqueshell
If the OP is using Chevron as his regular fill on a regular basis he is getting all the cleaning he possibly could because of the PEA (Techron)contained in their fuel. Maybe add a bottle of full strength Techron for the most complete effect.

In any case your rough idle is doubtfully the result of carbon on the piston tops/crowns.

You might have old plugs, worn cap or rotor, vacuum leak (strong possibility) or a dirty MAF sensor or O2 sensor.


Plugs were put it at 105,000 with oe ac delco platinums, they looked good and the gap was correct when I pulled them to look in the combustion chamber. No MAF sensor on these motors, or pcv, or distributor for that matter. Ignition coils are oe, plug wires are new-ish. Regardless, my definition of 'rough idle' is pretty nit picky; I don't even notice it when the motor is cold. When it does 'act up', it more like I can feel a very slight vibration in the seat, really not a big deal. More than anything I'm interested in methods for getting carbon off piston crowns

 

[SteveSRT8]

Anyone introducing any liquids into their intake manifold had better be careful. Unless you have a carburetor the intake manifold is likely a 'dry' design. These can allow puddling and will likely have extremely uneven distribution.

Varies wildly by design, but manifolds haven't been designed to distribute liquids since the introduction of Port Fuel Injection...

 

[Volvohead]

Originally Posted By: SteveSRT8
Anyone introducing any liquids into their intake manifold had better be careful. Unless you have a carburetor the intake manifold is likely a 'dry' design. These can allow puddling and will likely have extremely uneven distribution.

Varies wildly by design, but manifolds haven't been designed to distribute liquids since the introduction of Port Fuel Injection...



Exactly. Unless the fluid is being introduced at the throttle body in a misted form, water could pool up . . . or primarily wind up in one cylinder, greatly increasing the risk of a hydrolock if anything else goes amiss.

It sounds like this engine is just running a little rough. I'd start with a PEA or similar detergent additive, and then take a compression test to make sure there's not something going on that chemicals can't fix. Only then, perhaps a Seafoam via the TB, or LC20 or one of the other open-cylinder overnight soaks.

 

[DoubleWasp]

i once worked on a generator that was so carboned out, it wouldn't even start. I filled each cylinder with Amsoil Power Foam, let soak, and then cranked the engine with the spark plugs out to purge the cylinders. I had to do this, because the loose carbon freed from the pistons and combustion chambers was wrapping itself around the spark plug electrodes, and preventing ignition. I did this 5 or 6 times, and the piston tops became like mirrors. I finally started the generator, and it [censored] alot out of its exhaust. I did 5 treatments of the Power Foam through the intake before the engine finally settled into normal starting and operation.

I would definitely recommend this process for cleaning out cylinders on an engine with easily accessible spark plug holes.

 

[slowdime]

Originally Posted By: Volvohead
Originally Posted By: SteveSRT8
Anyone introducing any liquids into their intake manifold had better be careful. Unless you have a carburetor the intake manifold is likely a 'dry' design. These can allow puddling and will likely have extremely uneven distribution.

Varies wildly by design, but manifolds haven't been designed to distribute liquids since the introduction of Port Fuel Injection...



Exactly. Unless the fluid is being introduced at the throttle body in a misted form, water could pool up . . . or primarily wind up in one cylinder, greatly increasing the risk of a hydrolock if anything else goes amiss.

It sounds like this engine is just running a little rough. I'd start with a PEA or similar detergent additive, and then take a compression test to make sure there's not something going on that chemicals can't fix. Only then, perhaps a Seafoam via the TB, or LC20 or one of the other open-cylinder overnight soaks.

Makes sense. Wouldn't introducing seafoam via the TB pose just as great a risk of hydrolock?

 

[SteveSRT8]

Originally Posted By: slowdime

Makes sense. Wouldn't introducing seafoam via the TB pose just as great a risk of hydrolock?


It certainly could. It is all dependent on how it is introduced, where it goes into the manifold, the liquid's volatility, etc. There are a lot of variables.

Water doesn't automatically spell destruction for the engine, we used to run it in street cars back in the 70's so we could use more timing. But those cars had carburetors and hence a manifold designed to handle liquids...

 

[slowdime]

Would using a spray bottle directly into the TB reduce the risk? Even without a spray bottle I wasn't planning on dumping a huge amount of a yet-to-be-determined cleaner.

 

[JDW]

My water/meth setup works great for my non-intercooled roots blower . Have a 14 & 2 GPH nozzles , WOT temps never over 180 on air intake

I mix my own fluid 50/50 distilled water & methanol.

 

[leeharvey418]

Originally Posted By: JDW
My water/meth setup...

I mightn't go crowing about that on the interwebs...

 

[SteveSRT8]

Originally Posted By: slowdime
Would using a spray bottle directly into the TB reduce the risk? Even without a spray bottle I wasn't planning on dumping a huge amount of a yet-to-be-determined cleaner.


Yep, it should work fine. Less is more in this case. But caution is appropriate...

 

[Volvohead]

Originally Posted By: slowdime
Would using a spray bottle directly into the TB reduce the risk? Even without a spray bottle I wasn't planning on dumping a huge amount of a yet-to-be-determined cleaner.


With water, yes. At least a spray bottle provides some metering and atomization. I'm skeptical over how much help a spray bottle or two of water is going to do here. But give it a try.

With spraying SF or any of the volatile chemicals, exercise much more caution. SF is quite flammable. You don't want a flameback while you're spraying a bottle of that in your hand.

You can probably get by with a very carefully metered pour of SF, as it is much more volatile than water and should vaporize more quickly in a hot intake tract. By that, I mean no more than an ounce at a time right at the TB, waiting for the huge fog to dissipate each time (no stalling). If you don't have a nipple right at the TB, then just let it settle on the plate. You're basically mimicking a good shot of TB cleaner. Again, I wouldn't take a whole bottle of SF to it, in case of a flameback (extremely unlikely, but why take the slightest risk).

But again, running Techron concentrate through a couple tanks is much easier, and actually cleans more components that could be causing your trouble. The concentrate is 10x stronger than Chevron's gasoline dose; the gasoline is treated only to prevent deposits, the concentrate is for meaningful existing deposit removal. Do it right before an oil change. Remember also that one thing a detergent cannot clean is itself. So to the extent that the Techron in the gas is leaving any deposits (not saying it is), you may be better off using a different detergent chemistry. I only use Techron at this point, so I'll leave those suggestions to others.

 

[slowdime]

UPDATE:
I gave de-carbonizing with water a shot today using a spray bottle. At first I took the intake off and sprayed directly into the TB. The TB is mounted directly over the valve cover so I couldn't hold the bottle upright; not a whole lot seemed to go past the throttle plate because the distance I had to hold the bottle at to keep it upright. So I put the intake back on and tried a different way. I pulled one of the smaller vacuum lines (the same one I spliced my vacuum gauge into) and held the nozzle against the end of the hose and throttled up to ~3000rpm and sprayed away. When it would bog down I stopped spraying until the rpm picked back up to where it was.
In all I put about .5L in. I checked at the tail pipe and there wasn't any water pooled on the floor, but there was the smell of old farts and nastiness. I hooked the vacuum hose back up and went for a vigorous drive. While driving I had a CEL come up... I stopped by a parts store and borrowed their OBD tool and found out it was a cylinder 3 misfire. It didn't feel like it was misfiring while driving or when I idled at a stop light. I went ahead and cleared the code and I'll keep an eye on it.
When I was done driving I pulled each of the plugs and had a peek into the combustion chambers of each cylinder. They look maybe marginally cleaner, it's really tough to say looking through such a small hole with a flashlight though. Without removing the head or looking with a scope that's the best I can see. It felt smoother while idling but this is a pretty subjective seat of the pants thing.
While at the parts store, I checked out a bottle of techron, for $13.99 it can wait til my next paycheck; I need that money for actual gas in the meantime! Question: would putting a full bottle of techron on a half or quarter tank or so be of any benefit? I also saw some stuff for $4 called 'Berryman fuel system cleaner', never heard of it; anyone here?
Note: I re-checked the gap on the plugs while they were out and found cylinder 1 to be at .055 and 2 was at .050 (they're supposed to be .040), so they're now corrected.

 

[Electrajoe]

After one of those ½ gallon water clean ups - an oil change would probably be due.

Some of the water will probably seep past the rings diluting the oil.

 

[circuitsmith]

Does this exist?:

A small wire brush, bristles arranged in a ball shape, on the end of a coiled wire flexible stalk.
Kinda like a mini bottle washer.
This could be slipped in the spark plug hole and spun with a slow drill.
I'd turn crank to TDC valves closed first.
That could break up the flaky carbon at least, then blow it out with an air jet.

 

[SteveSRT8]

Originally Posted By: circuitsmith
Does this exist?:

A small wire brush, bristles arranged in a ball shape, on the end of a coiled wire flexible stalk.
Kinda like a mini bottle washer.
This could be slipped in the spark plug hole and spun with a slow drill.
I'd turn crank to TDC valves closed first.
That could break up the flaky carbon at least, then blow it out with an air jet.


Unlikely to do much in a 3 or 4 inch bore V8 when the plug hole is so small.

Knowing the abrasive nature of carbon I would think twice before knocking it off the tops of my pistons mechanically. Some particles are bound to make it down the small gap between the piston and the cylinder bore.

Much more fun to hit the open road for some sustained full throttle work...