Ford CSG-850 / WSG-858 — Compression Gauge Check
Testing & diagnosis · Engine cylinders
For the Ford CSG-850 / WSG-858, from the Ford service manual.
Browse Ford generators & specs →
Procedure
- Engine at normal operating temperature; remove all spark plugs.
- Set the carburetor throttle plates in the wide open position.
- Install a compression gauge in No. 1 cylinder.
- Crank at least five compression strokes with ignition OFF and record the highest reading.
- Repeat the test on each cylinder with the same number of strokes.
- Lowest reading cylinder must be within 75% of the highest reading.
- Squirt one tablespoon of engine oil on pistons of low cylinders and retest.
- Improved compression means rings; no change means valves; two adjacent low cylinders means head gasket.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Lowest reading must be within 75% of highest
Source: Ford service 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.