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Accusump Installation in an '88 M3

Figure 1

The unit is a 1 qt. electric valve accusump, Canton part no. 24-044, $250., with a pre-oiler installation kit, including fittings and hose, Canton part no. 24-196, $50. A Canton billet sandwich filter adapter, part no. 22-565, $50., was used to connect the hose to the engine oiling system. A few other fittings may be needed.

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My unit was mounted under the hood in front of the left shock tower on the inner fender, above the cruise control unit. A piece of angle iron was bolted to the inner fender. An extra angle was added as a support to clear the cruise control. The body of the accusump was secured to the angle iron with worm gear duct clamps, not the mounting clamps that came in the kit. The solenoid valve was placed alongside the cylinder of the accusump, connected by " brass elbows. This arrangement allows the hood to close normally. This location should work with later models that have SRS shock sensors mounted in this location, although the valve body may have to be repositioned slightly. The hose is connected to the solenoid valve and the sandwich adapter by brass fittings. Mounting of the sandwich adapter requires a 1 1/8" socket.

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The total weight of the accusump with valve and oil is about 8 lbs. Even mounted relatively high and to the side, the effect on handling should be very small. The accusump should not be placed near heat sources, such as exhaust manifolds, as the heat could cause the unit to overpressurize. The left fender is one of the cooler places under the hood. The cylinder must be clamped at the ends only; any distortion of the cylinder may prevent movement of the piston inside.

I have arranged the switch control to be placed on an inside dash panel. The switch in position 2 allows the accusump to remain on whenever the ignition is switched on. In this position, the engine will be pre-oiled, and the accusump will be available to prevent oil starvation. When turned off, however, the pressure in the bottle will be whatever the engine was producing when shut down, leaving minimal pressure for pre-oiling the next time the engine is started, unless the engine is briefly run at higher rpm before turning off. In position 1, the engine is pre-oiled until minimal pressure is reached. By grounding the relay through the oil pressure sender, the accusump will automatically shut off when the engine reaches the pressure of the sender (around 10 psi). This prevents dry starts, and avoids having to rev the engine before shutting down in normal use. When the solenoid valve is off, it still allows the bottle to fill. This means it will retain the highest output of the pump, until re-energized. The center-off position is useful if you want the ignition on without either running the engine or draining the bottle.

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The relay, switch and pilot light are Radio Shack parts. A useful place for an accessory tap under the hood is the accessory fuseblock, a little unit clipped to the outside of the main fusebox. There are two wires entering the accessory fuseblock: a large red wire, that is hot all the time, and a smaller green wire that is ignition switched. This is the one that you want. Each wire has a socket for a single flat blade of a fuse. I have tried to add the other socket: the dealer has two styles of fuseblock inserts; neither of them seem to fit. I finally soldered a small brass strip to the end of a wire and inserted it into the socket holder. It works fine with a fuse inserted, and it reduces the "homemade wiring" look.

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The console panel is homemade from 1/8 acrylic. A paper pattern was made, tranferred to the sheet plastic, which was carefully folded using gentle heating from a torch. As you can see, the cigarette lighter and ashtray have been removed (shouldn't be smoking anyway!), although a 12v socket has been placed in the panel, as well as a remote radar detector and an oil pressure gauge. The light from the cigarette lighter was remounted behind the plastic panel to light the coin holder. (The shift knob is homemade, too). The switch and pilot light have been placed next to the oil pressure gauge. Another location might be in one of the small rectangular plastic inserts in the dash next to the speaker balance control. The installation of a sandwich adapter at the oil filter mount is an excellent time to add a sensor for an oil pressure guage, a project that goes well with the installation of an accusump.

It is not really necessary to add any of this switch wiring or make a new panel; all you need is to wire the valve directly to an ignition hot lead under the hood. My additions just make the use of the accusump somewhat more flexible.

This arrangement should provide the advantages of pre-oiling, together with a modest reserve for track or autocrossing, without the dangers of overfilling the crankcase. In addition, it allows the retention of all stock equipment, so no convenience or comfort equipment need be removed.

In operation, when the car is started from cold, with the switch in auto shutoff position, the pilot light comes on with the turn of the key to ignition on. It takes from 2-7 seconds for the light to go off, but you can see the pressure gauge needle move as soon as the key is turned. Once the engine warms, the pressure comes up instantly on starting. I figure a safe oil level would be about halfway between full and add. This leaves room for a 1 qt. tidal addition if the accusump should discharge fully, with only about a qt overfill.

What will this 1 qt unit Not do? If you are on an oval track, or hole out your oil pan on a rock, 1 qt will only give a few seconds reserve of oil pressure. Also, the auto pre-oiler feature is minimal; it gives minimal oil pressure at starting, although it eliminates any dry starts. Improvements might include a higher pressure sender, or a timer that opens the valve for about 10 seconds, then shuts off. A future upgrade: an aeroequip hose would probably be better in the long run. Parts were ordered through Racer Parts Wholesale. I would forego the installation kit, and order aeroquip hose and fittings. 26" of AN-6, or AN-8 hose, plus 2 AN/NPT fittings would be cheaper and better than the CM installation kit.

Please send questions or comments to: drautox@comcast.net

Last Modified June 23, 2002