Ring-groove carbon is a dimensional problem wearing a cleaning costume: every mechanical method that removes the coke also removes or deforms metal the rebuild is required to keep. This documented application study cleaned the ring belt of a large-bore diesel piston in hot Brulin chemistry without anything touching the groove.
The contamination
Coked carbon
Thermally polymerised in the ring belt over thousands of hours — insoluble in solvents, concrete-hard, and bonded into the groove roots where no tool reaches without contacting the flanks.
Lubricant ash
Mineral residue from burned oil packed behind the carbon banding — chemistry alone will not lift it; it needs cavitation working in place.
The dimensional trap
Scraping, wire-wheeling and blasting all remove or peen the groove flanks. A groove outside width or flatness spec scraps the piston — the cleaning method must be non-contact.
How these pistons were cleaned before
Soak for 24 to 72 hours
The pistons sat in a soak tank for one to three days to soften the oil and loose soil. The hard carbon in the ring belt stayed on.
Then sand or bead blast
The carbon came off by hand, with abrasive paper or in a bead blast cabinet. It takes a lot of operator time on every piston.
One slip scraps the piston
The skirts carry a coating. A moment's inattention at the blast cabinet takes the coating off or marks the grooves, and the piston is replaced with a new one at a cost of thousands of dollars.
The process
| Parameter | Value |
|---|---|
| Chemistry | AquaVantage 815 QR-NF at 10% v/v |
| Temperature | 70 °C |
| Frequency | 25 kHz, sweep |
| Cycle | Staged cycles with inter-cycle filtration |
| Verification | Groove width, depth and flank flatness gauged against drawing after cleaning |
Before, during, after
The results
Hardware and chemistry
Heavy-duty industrial ultrasonic tank
25 kHz with sweep, heated to 70 °C, weir and bag filtration keeping removed carbon out of the bath. Sized to the largest piston in the rebuild program.
Talk to us about tank sizing →
AquaVantage 815 QR-NF
The MRO-grade carbon remover in the AquaVantage range — formulated for baked and coked soils on rebuild work, free-rinsing, with corrosion inhibition.
View the product, SDS and TDS →From a single trial piston to a documented production process.
Questions about this process
Why not scrape or blast the grooves?
What chemistry and settings?
What about the dimensions?
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