Cleaning carbon from engine internals

[aww999]

I've got a new head which is going on my Supra as the old one has been skimmed too many times to be useful (compression too high). Never been skimmed, but unfortunately off a bit of an oil-burner by the looks of things. I have managed to clean the thick carbon deposits off one of the chambers using a toothbrush and some methylated spirits, but that took almost an hour and the stuff smells absolutely vile!

The head is aluminium so I can't use a wire brush on it . . . can I get a brass brush or something along those lines to abrade the carbon a bit more without marking up the aluminium? Also, is there something better to use as a solvent? Petrol? Diesel? White spirit?

The forged ally pistons in my current engine (the shortblock is not being messed with) have got a bit of carbon on them, just a thin layer of black - I guess I don't need to bother about trying to clean this?

Also, the exhaust valves from this head are fairly well encrusted with rock hard . . . stuff. I have had success in the past cleaning these up by putting them in the chuck of a drill and spinning them against a wire brush, fairly time consuming though with a 24V head . . . is there a better way?

Thanks guys!

[slinky]

A copper brush should do the job.. or a local metal cleaner/finisher should be able to help out...

hth..

slinky
587racing.com

[steve_d]

I have used a strip of wood in the shape of a chisel to clean heads. The gasket face can be cleaned with a steel chisel (the wider the better) you just have to be careful you don't scratch the surface.

To do the valves start by scraping off most of the carbon with a knife. The valve is that hard you are unlikely to be able to do any damage then finish off with the drill/brush combo.

If you want to clean the pistons you can use a wooden scraper but leave a ring of carbon 3-4mm wide around the outside against the bore. This is supposed to help prevent oil burning. I have no idea why but was taught this when I was 15 and have done it ever since. If you have one, place an old piston ring in the bore on top of the piston. This is your guide for the 3-4mm.

Steve

[Trooper2]

steve_d said:

If you want to clean the pistons you can use a wooden scraper but leave a ring of carbon 3-4mm wide around the outside against the bore. This is supposed to help prevent oil burning. I have no idea why but was taught this when I was 15 and have done it ever since. If you have one, place an old piston ring in the bore on top of the piston. This is your guide for the 3-4mm.

Steve

The carbon inside of an engine is like a sponge, it will absorb oil, fuel, etc. That is probably why it helps to control oil burning.

[350matt]

Apparently a mix of Mr muscle oven cleaner and unleaded petrol works very well, but don't breathe in fumes, get on skin etc etc

This advice is freely given with no comebacks or liabilty, inferred or otherwise.....



Matt

[GreenV8S]

Does steam cleaning work? Water injection is supposed to be very effective at keeping the insides scrupulously clean, because the steam reacts chemically with the soot. I don't know if you;d get a similar effect just blasting steam at the thing, but it's worth a try I would have though, and might dislodge it even if the chemical thing turns out to be a red herring.

[Pigeon]

Steam cleaners don't get anything like hot enough to make that reaction work, but the pressure and heat of the jet will still do a pretty good job.

The top tool for cleaning gasket faces is a broken sharpening stone wetted with diesel or paraffin, or even petrol.

[wildoliver]

Very gentle and careful use of rotary wire brush, but avoid the sharp edge of the combustion chamber or you will have gasket sealing issues.

[aww999]

The head needs to be skimmed (these things are so long that they warp if you so much as look at them funny) before it goes back on so I don't need to worry about cleaning the sealing face, I'll just get the worst of the old gasket off it before it goes away.

Just had a look in the kitchen cupboard, and we have some oven cleaner. It says it's not safe for aluminium though, I ill have a go on my old head before risking it on the new one. The copper brush sounds like a good idea, I don't think I'm brave enough to try a wire brush though!

[Howitzer]

Unless you are stripping the engine down completely, don't even bother cleaning the pistons as you will only trap carbon around the rings and possibly damage the bores, seen it happen loads of times at work and this was in controlled envirnoments etc.

Dave!

[Pigeon]

aww999 said:

Just had a look in the kitchen cupboard, and we have some oven cleaner. It says it's not safe for aluminium though, I ill have a go on my old head before risking it on the new one.

I wouldn't, it's caustic soda and it goes for aluminium in a big way. Useful for making hydrogen but not good for your head

For a mild "etch clean" effect washing powder is pretty good but do rinse it off thoroughly afterwards.