JDS Exhaust Pressure Tester

A product review by Alan Trimble, BATauto.com Associate Editor

Exhaust restrictions can be difficult to pinpoint. An intake manifold vacuum test will verify that an exhaust restriction is present, but it cannot pinpoint the location of the restriction. Is the catalytic convertor plugged? Did a baffle come loose in the muffler? Is a double-wall pipe collapsed internally? This tool will answer those questions and more.

The kit comes in a surpisingly compact case.

The contents of the kit, removed from the storage case. The kit includes a drill bit, a 1/8" NPT tap, a test probe, pressure hose and gauge, and twenty 1/8" NPT plugs. A succinct instruction sheet (not shown in photo) is also included.

We tested the unit on several vehicles. The vehicle shown in the photos is a 2002 Mercury Sable.

Shown in this photo is the downstream catalytic convertor. Note the Inlet and Outlet are marked "I" and "O" in grease pencil.

We drilled the inlet and outlet per the JDS instruction sheet. We found that it was easier to drill and tap the pipe if we gently flattened a small portion of the pipe and then center-punched the flat spot. This prevented the drill bit from 'walking' and allowed the tap to get a better initial bite. IMPORTANT: Follow the JDS instruction sheet when tapping the hole. The pipe plugs WILL NOT FIT if you tap too deep.

The probe is installed next.

The pressure hose is attached to the probe. The opposite end of the pressure hose is attached to the gauge (not shown).

We temporarily taped the gauge to the instrument panel in order to monitor exhaust pressure under different RPM and engine loads. To our surprise, the OEM Ford exhaust system was extremely effiicient. The gauge registered 0 PSI under most conditions, .5 PSI under wide open throttle at 4000 RPM. This is well within the 'normal' range shown in the JDS instructions.

We have confirmed that the exhaust is not restricted on this car, so there is no need to test the convertor outlet. Had the results differed, we would have moved the probe to the outlet side of the catalytic convertor and re-tested. A high inlet pressure and a low outlet pressure would indicate a restricted covertor.

The test is now complete. We removed the probe and installed the supplied pipe plug. Be extremely careful when installing the plug. 1/8" NPT pipe thread is very fine and therefore very easy to strip, especially on a stainless steel exhaust system such as this one.

This test took about 20 minutes. That includes the time needed to set up and shoot the photos shown here. We found the tool to work as advertised. It quickly eliminated a restricted exhaust as a possible problem with this car. The tool really shines when used on cars with a plugged catalytic convertor or collapsed pipe or muffler. One can pinpoint the source of the restriction in a few minutes.

The JDS Exhaust Pressure Tester is no longer available, but we now are carrying a couple similar tools in our tool store. These tools will likely pay for themselves the first time they are used.

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