Clean Carbon Off Cylinder Heads
Article by Vintage Vinny
There are several modern methods for cleaning carbon off cylinder heads; soda blasting, media blasting, vapor blasting, walnut shell blasting, etc. But for the DIYer who's on a budget or just likes to do things himself, there's spray degreaser and elbow grease.
What you'll need is a spray or liquid degreaser, a soft wire brush, and some Emery cloth.
For aluminum, a brass cleaning brush will help prevent accidental scratching or gouging.
Cleaning Aluminum Heads
Aluminum heads, like this one from a Norton Commando, can be made to look as good as new. However, caution must be taken not to scratch the aluminum alloy material--do not use steel scrapers or a screwdriver blade!
To determine what kind of material your cylinder head is made out of, stick a magnet to it. A magnet will stick to cast iron but not to aluminum.
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CAUTION: On aluminum heads, power tools can really do more harm than good.
Roloc discs should be used sparingly and only on the heavy stuff.
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As you can see from the picture below, this Commando was running way too rich! It left valves and ports coated with black carbon.
Getting Started
You'll need a valve spring compressor to remove and install valves and valve springs.
The tool in the picture was designed to fit Harley Big-Twins and Sportsters, but it's really a universal tool.
Any gasket remnants should be carefully removed with a gasket scraper and/or fresh razor blade.
This 'repurposed' baking pan gets a lot of use in my garage. It also doubles as an oil change drain pan.
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Best Degreaser For Engine Parts
There are several good degreasers out there (Purple Power, POR-15, Spray 9, Super Clean, etc). For cylinder head cleaning, I always get good results with Purple Power in a Spray Bottle.
Let The Degreaser Soak
Spray straight into the ports and let it soak the heavy stuff for a while. The longer you let it soak, the easier it will be to remove.
For best results, prop up the work so that ports are horizontal.
If you give the degreaser time to work, the carbon deposits will come off easily with a wire brush (brass brush for aluminum heads). For hard-to-get areas, a smaller parts cleaning brush or an old toothbrush can be used.
On stubborn, built-up areas, sand lightly with small squares of Emery cloth folded over.
If needed, final sanding can be done with 400 or 600 grit wet/dry paper.
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Cleaning Valves
There are a several methods to remove carbon off engine valves. Thick carbon deposits can be removed on a bench grinder with wire wheel attachment.
TIP: Head bolts can also cleaned on a bench grinder with wire wheel attachment.
After the heavy stuff is removed, I wrap some masking tape around the valve stem, and chuck the valve in my drill press, lightly sanding with progressively finer steel wool.
Read: 7 Drill Press Uses For Motorcycle Repair
The same results can be gotten with a hand-held drill mounted in a work bench vice.
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Rinse With Running Water
After cleaning/degreasing the head, rinse well with water. For those without a sink in their garage, an outdoor water faucet works just as well.
After a thorough rinsing, blow-dry all ports, fins, and openings with compressed air.
50 year-old Norton Commando head ready for assembly.
Conclusion
As an alternative to vapor blasting and other expensive methods, cleaning carbon off cylinder heads with degreaser will guarantee every inch of the head is gone over. It will take longer than modern methods, but results will be the same. And you don't have to ship it out and wait weeks or months for it to come back.
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