The Other Side of the Pump - August - 2016


Many years ago I took an electrical course at ATRA. One of the things they instilled in us was the importance of “checking the grounds.” Of course, that was in the early days of electronic transmissions; I won’t say exactly how long to avoid aging me, but let’s just say it was before OBD-II became a standard.

You may ask what that has to do with torque converters. Well actually, bad grounds can have quite a lot to do with the life of your converter and pump, and, obviously, the life of your newly rebuilt transmission.

To illustrate the importance of getting the grounds right, let me share a story I heard about a general repair shop that performed a valve job on a truck. To access the heads, they lifted the cab off the chassis. Unfortunately, when they reassembled it, they forgot to reconnect the ground straps.

The road test only lasted about two miles; then the technician sat and waited for a tow truck to haul the rig back to the shop, where they discovered the pump bushing had welded to the hub. This meant the shop was up for a pump and a converter, which most likely ate the profit from the valve job!

While you need to be aware of the grounds with all transmissions, it’s particularly important with heavy-duty units, such as the Ford 5R110. Make sure all surfaces are clean and free of paint. If the transmission case has been painted, clean the paint from the block mating surface and check that the block surface is also clean.

Check the crank pilot and make sure there’s no rust or damage, so the converter can fit correctly. Many converter rebuilders paint the converter; if the pilot is painted, remove the paint and grease it lightly.

To check the ground system, connect the positive lead of a voltmeter to the starter body and the negative lead to the negative post of the battery. Watch the voltage when engaging the starter: If the meter indicates more than 0.2 volts, you have a ground problem.

For additional protection, you can add a ground strap from the frame to the starter, the block, or the bellhousing. Once again, make sure all the surfaces are clean and free of paint or rust.

Obviously there are other issues that can cause pump or converter failure; we’ll look at some of them in future articles.

Nobody likes to see a comeback, so it’s worth taking those extra few minutes to make sure you’ve verified the grounds.