DIY: Installing a Mechanical Oil Pressure Gauge (B18 Block)

DIY: Installing a Mechanical Oil Pressure Gauge (B18 Block)

Article Written By: Ty MacWalters

A good way to monitor how you engine is performing is to install a mechanical oil pressure gauge. Over the years the internals of the engine tend to wear down showing the signs of an engine in need of repair. By simply installing a mechanical oil pressure gauge you can tell if the oil pump is dieing, engine bearings needing to be replaced, or that you simply have too much or not enough oil in the engine. The stock oil pressure-sending unit performs two jobs and only gives a vague reference. The stock sending unit was only intended to tell the operator of severe problems; oil pressure 5psi or lower and very low quantity of oil.

Tools and Parts Needed for this Project:

1. A Mechanical Oil Pressure Gauge

2. A Oil Pressure Gauge Installation Kit (consist of lines, fittings, and gaskets)

3. Mounting Hardware

4. 1/8” NPT to 1/8” BSPT fitting

5. Teflon Thread Tape

The first step is to determine the location where you intend to mount the gauge. Remember you want the gauge in a place where you can monitor it while you’re driving. Most severe engine damage can be avoided if the engine is shut off at the first sign of a mishap, so mount the gauge in a well visible location. Many people choose the A-Pillar to mount their aftermarket gauges, but some companies have come out with gauge application where you can mount gauges on the trim around the stock gauge cluster

Example of an A-Pillar gauge installation:

Next you want to take that oil pressure gauge installation kit and assemble the fittings as specified in the kit and route the hose through the grommet in the firewall. Now that you have decided where to mount the gauge and assembled it is time to start the removal of the stock oil pressure-sending unit. On the B18 blocks the stock sending unit is located under the car just left of the oil filter, the electrical connector to the sending unit will resemble a spark plug wire and may require so twisting to remove. When removing the stock sending unit there will still be the electrical connectors laying around the best suggestion to keep that connector save is to zip-tie it to safe location away from moving parts, you may want to reuse the connector again at a later point or feel that you want to have both the “idiot light” and a mechanical gauge. Now that the electrical connector for the stock sending unit is secure its time to remove the sending unit itself. You can pick up a special tool from your local parts store, but if you have a deep socket 15/16 socket then you should be able to remove the sending unit by turning it counter clockwise. Since the mounting place is above oil line you don’t have to drain the oil, neither should any oil come out when removing the stock sending unit making this a clean and simple job. Now that the stock sending unit has been removed from the block clean and prep the area around the hole making sure that no dirt is in the threads.

When installing the new sending unit you have two choices; to connect the gauge fitting directly to the block or use a “T” connector allowing you to have both the stock sending unit and gauge.

The problem with this configuration is that most “T” connectors are made from brass that is a very brittle metal that over time could brake leaving a high-pressure hole in the block allowing a considerable amount of oil to escape while the engine is turning. Tuner Toys.com has come out with a special “T” that is made from steal that wont break as easily.

The advantages of having a “T” connector are the ability to keep the stock warning light in the instrument panel. The likely hood of you noticing a red light over a moving needle on a gauge is more probable. The Tuner Toy application also leaves an available fitting for a turbo application.

If you decide to go without the “T” connector and go for just the mechanic gauge then you will need to buy a part from you local Autometer Gauge Retailer. The part # you will need to order is 2269. The part required to match up your 1/8" NPT gauge fitting to the block is what they called a Metric converter. 1/8" BSPT (male) to 1/8" NPT (female). The difference between 1/8” NPT and 1/8” BSPT is negligible but when you are talking about screwing a fitting into a block, one will strip the block and the other will create a secure tight fit.

-NPT 1/8" is 27 threads per inch (Tapered thread)
-BSPT 1/8" is 28 threads per inch (Parallel thread)

Make sure that you connect the metric converter to the gauge end first using Teflon tape around the threads make a snug and secure seal. Then you can start installing the connector to the block. The line may twist in a loop, don’t worry this is a good thing. It’s a strain relief on the hose and will ensure smooth flow to the gauge giving you an accurate reading from the block.

Now that you have installed your new oil pressure gauge, start up the engine and give it a moment so that the oil can be sent to the gauge. If the engine is cold you will notice that the needle will jump up pretty far. This is normal since the engine is at higher revs then when it is warm. You will notice as the engine gets warmer that the oil pressure may drop, this is normal as the oil warms up the pressure will decrease. If you are getting inaccurate readings then specified by the manufacture check the line for possible bends or kinks in the line, the line should be as short as possible with as little curves and bends as possible if there are problems you may have to cut the hose are redo the fittings.

Manufacture oil pressure guidelines (hot)

At idle – 10psi

At 3000 rpm – 50psi

If there are no problems in the line and you are still outside the parameters then check the oil level and if the oil level is correct then you might have a worn engine bearing. Remember too much oil in the engine will cause lowering readings even as much as a ½ a quart can affect the readings. So if you are adding an additive in the oil make sure you compensate for the extra quantity.