This procedure will allow you to install a oil pressure sending unit on your car, without having to disturb the stock "warning light" oil pressure switch. There is an extra hole on the housing, that is simply just not machined through all the way. All you need to do is continue the existing hole (drill it through to the oil passage), and then tap it for 1/8" NPT threads. Most of the time needed will be spent removing the filter housing from the car. You need to remove the front cover to get at one of the bolts for the oil filter housing. That is always a pain - not hard or anything... just a pain.

To get the front cover off, you need to loosen all the v-belts, remove the water pump pulley, and remove the harmonic balancer. You may need to lower that side of the engine to get the harmonic dampner off the engine. You do this by loosening, or removing the motor mount on the drivers side, while supporting the engine with some sort of jack under the oil pan. I used a hydrolic bottle jack with a 2x4 on it to spread the load. Then, you need to remove like 8 bolts from the cover itself. If you don't have a service manual to show you where the bolts go, make sure you keep track. There is 6 different bolt lengths between the upper and lower covers.

Once the lower cover is off, you can remove the 4 bolts that hold the oil filter housing to the engine. Keep track of those 4 bolts as well, as they are different lengths.

Once the filter housing is in your hands, it probably will take 5 minutes or less. It's just a matter of drilling down through into the oil passage, and then tapping the hole. Since it's aluminum, it is VERY easy. I used a 1/4" drill bit to drill through into the oil passage. It's smaller than the existing hole, but it doesn't matter. Then, use a 1/8" NPT tap to put threads in the existing hole.

Clean, clean, clean. There are going to be lots of metal shavings from this mod. Use some brake cleaner, or at minimum, compressed air to get the shavings out of the housing. Once everything is clean, install the sending unit in this new hole (use teflon tape to seal the threads), and reinstall the housing on the car. Of course, you should also have a new gasket to reinstall the filter housing to the block. (Part number MD185528)

Full view of the oil filter housing off the car.

If you are installing a turbo on your 4G64, this is the plug that must be removed for the oil line
to the turbo. The other plug shown is unfiltered oil straight from the oil pump.
The plug pointed to by the arrow is filtered oil.

On the car, this is where the hole is that needs to be drilled & tapped for an extra oil pressure sensor. Drill it through to the oil passage with a 1/4" drill bit, and tap it with an 1/8" NPT pipe tap. If you try to do this on the car, you WILL get metal shavings in the oil passage. However, since this oil passage is before the filter, the shavings should get caught in the filter the first time you start the car. Do it at your own risk!

View of the hole from the engine side of the filter housing

Close up of the hole

View of the whole filter housing bottom side with the hole drilled & tapped.

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This page and its information © Curtis V. Shambeau
To contact me, please email me at curt@execpc.com
Last updated 6/19/2004