Harbor Freight has a $25 diesel compression tester with the necessary adapters to go in through the glow plug holes. Need the 90 degree adapter on at least one. Pull a vacuum on the shut off valve while doing the test to stop fuel flow.

Warm engine. Pull all the glow plugs, pull the vacuum on the shut off, install tester in one hole, crank engine for a number of compression strokes. Read gauge. Move to the next.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13