Cummins/Onan QSX15 / QSx15 — Air Compressor Carbon Buildup - Maintenance Check

Maintenance

For the Cummins/Onan QSX15 / QSx15, from the Cummins/Onan operator's manual.

Applies to: Cummins/Onan QSx15, Cummins/Onan QSX15 engine

Procedure

1. Drain air system wet tank to release system air pressure.
2. Remove air discharge line from air compressor.
3. Measure total carbon deposit thickness inside air discharge line.
4. If total carbon deposit exceeds 2 mm [1/16 in], inspect cylinder head assembly and discharge line. Replace if necessary.
5. If cylinder head replacement does not correct problem, replace compressor assembly.
6. Check air discharge line connections up to first tank until total carbon deposit is less than 2 mm [1/16 in]. Replace lines or connections that exceed specification.
7. Inspect air driers, downstream air valves, and air governor for carbon deposits or malfunctioning parts.

Full service-parts list: Cummins/Onan QSx15 →

Source: Cummins/Onan operator's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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