Installing an Oil Pressure Buzzer

By David A. Guptill

Originally published in the Austin-Healey Magazine, September 1983


A number of people have fried the bearings in their engines or been stranded due to the sudden loss of oil pressure caused by a blown oil cooler line, a blown oil filter “O” ring, or a hole in the oil pan. The following is a simple and inexpensive means of warning the driver without the need to keep one eye glued to the oil pressure gauge.


PARTS LIST

100-4

1 - ¼” Pipe Street “T” (see Fig. 1) 1 – Joint Sealing Compound 1 – Oil pressure Switch with ¼” Pipe Threads 1 – Any 12 V Buzzer (that doesn’t draw high amps)

​100-6 & 3000’s

1 – 1/8” Pipe to 1/8” tubing adaptor (see Fig. 2) 1 – Oil pressure switch with 1/8” Pipe Threads 1 – Joint sealing compound 1 – Any 12 V Buzzer

These instructions assume that your Healey has the stock engine and wiring. If not you’re on your own!


Installation of the Switch


100-4


On passenger side of engine near rear, locate oil pressure hose for safety gauge. Disconnect oil hose from adaptor. Remove adaptor. Clean the threads of the adaptor. Apply thread sealing compound to threads of the adaptor and screw the adaptor into the “T”. Clean threads in block, apply thread sealing compound to the “T” and screw “T” into the block, with the leg of the “T” pointing towards the front of the engine. Apply thread sealing compound to the oil pressure switch and screw switch into “T”. Reconnect hose to adaptor. Start engine. Check for leaks. (see Fig. 3)


100-6 & 3000’S


It’s easier if you remove the oil filter first, but it’s not necessary. On the passenger side of the engine near the rear, below the rear lifter cover, there is a projection for the oil pump drive. There are two oil passages in the projection. The rear one is plugged with 5/16 – 24 bolt. The other is either plugged with a bolt or has an oil line for the Tach drive. Remove the bolt that points to the rear and clean the threads in the block. Apply thread sealing compound to the adaptor and screw it into the block. Don’t play “Muscleman” because it is small and made out of brass. You could break it. Re-install the oil filter if you removed it. Start the engine and check for leaks. (see Fig. 4)


Buzzer installation


All cars:


The beat place to mount the buzzer on the firewall next to the steering column. This is a large hollow box that does an excellent job of amplifying the sound of the buzzer.


Wiring all cars:


Basic Buzzer


The easiest place to get power is at the fuse box. One fuse has power all of the time. This fuse is for the horns. The other is for accessories and is controlled by the ignition switch.

Run a wire from one terminal on the buzzer to the oil pressure switch. Run another wire from the other terminal on the buzzer to the terminal on the fuse box with the WHITE wires. If your wiring harness is old and faded, with ignition OFF touch the wire to each of the terminals of the fuse box. You don’t want to use any terminal that causes the buzzer to sound, because this would cause the buzzer to sound anytime the car is not running. Remove the fuse from the terminals that did not cause the buzzer to sound.


Turn the ignition switch on. Touch the wire to the terminals that did not cause the buzzer to sound with the ignition switch off. Find the terminal that causes the buzzer to sound. Turn the ignition switch off. Connect the wire to the terminal that caused the buzzer to sound with ignition switch on. Replace the fuse.


You don’t want to connect the buzzer to the other side of the fuse because the ignition and fuel pump are not fused. If the fuse blows, the buzzer will not sound if you lose oil pressure.


Turn ignition switch on. Buzzer should sound. If not, check your wiring. Start engine. Buzzer should stop just before the needle on the safety gauge starts to move. The switch responds faster than the safety gauge because the fitting between the block and the hose to the safety gauge has a small hole in it to dampen out minor fluctuations in oil pressure. Without this dampening action, the needle of the safety gauge would vibrate rapidly causing early failure. The dampening action slows down the response time of the gauge. The oil pressure switch does not require this dampening action. Most oil pressure switches operate between 5 and 10 PSI.


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