GEARWRENCH 3343D Engine and Transmission Oil Pressure Test Kit

The GEARWRENCH 3343D is the gauge kit you hook up when a transmission is slipping, flaring, or shifting late and you need to know whether it is actually making line pressure before you pull the unit. It threads into the transmission case test port and reads hydraulic pressure directly, which is the difference between a diagnosis and a guess.

The kit ships with a long section of hose so you can route the gauge up to the windshield and watch pressure while you drive. That lets you see line pressure rise and fall across the 1-2, 2-3, and 3-4 shifts and confirm whether the pressure regulator, pump, or a leaking clutch circuit is the problem. A pump that cannot build pressure, a boost valve that will not command rise under load, or a case circuit bleeding off will all show up here as numbers instead of symptoms.

Because it also covers engine oil pressure, the same box does double duty for a bearing-knock or low-oil-pressure diagnosis. It works on domestic cars and light trucks plus most import cars and light trucks, and includes an assortment of brass adapters and fittings to match the common port threads you will run into.

Note the gauge is rated to roughly 300 PSI, which covers normal automatic transmission line pressure and engine oil pressure readings; do not connect it to a circuit that spikes well past that. Always look up the correct test-port location and the specification range for the transmission you are checking so you know what a good reading looks like.