OTC 5605 Deluxe Compression Tester Kit for Gas Engines

The OTC 5605 is a complete compression tester for gasoline engines. You thread the right adapter into a spark plug hole, crank the engine over four or five compression strokes, and read cylinder pressure straight off the gauge. It is how you separate a mechanical problem from an ignition or fuel problem before you start pulling a head. Low, even readings across every cylinder point to worn rings or a tired engine; one cylinder low on its own points to a burnt valve, a cracked ring land, or a head gasket leaking between cylinders.

The kit covers 10mm, 12mm, 14mm, 16mm, and 18mm spark plug threads, so it fits most import and domestic four, six, and eight cylinder engines. It includes an 8-inch deep-well 14mm connector for recessed plug wells and a dedicated Ford Triton 16mm adapter that a lot of cheaper kits leave out. Adapters seat on both flat and tapered plug seats and carry a nickel plating so they do not corrode in the case.

The gauge is a 2-1/2 inch dual-scale head reading 0-300 psi and 0-2100 kPa, wrapped in a rubber boot and fed by a 25-inch flex hose with a quick coupler. The long hose lets you route the gauge up onto the cowl or fender so you can watch the needle from the driver seat while a helper cranks. A side pressure release dumps the reading between cylinders without unscrewing anything. Everything stores in a blow-molded case, and OTC includes a small repair bag with spare valves and O-rings.