FREE TOOL · ENGINE DIAGNOSIS
Compression test target
Static CR predicts the compression pressure you should read at cranking RPM. Big variance between cylinders or to spec indicates wear (rings / valves / head gasket).
Diagnosis
What to look for:
- Variance < 10% between cylinders = healthy.
- One cylinder 10-15% low = single cylinder issue (valve, ring, gasket).
- Two adjacent cylinders both low = head gasket between them.
- All cylinders low together = general engine wear or worn rings.
- Add 5 mL oil to cylinder, retest: if compression rises, rings are worn. If unchanged, valves leak.