oil pressure guage

kdogg233 · Post by **kdogg233** » October 15th, 2006, 11:17 am

i want to install an oil pressure guage in my 92 mx3 6 cyl and have no clue where it goes to on the motor can anybody tell me where the sensor for the oil pressure goes. Ive look for a chiltons book around me in the auto stores but cant find any that have my year mazda in them

1992blazeredgs · Post by **1992blazeredgs** » October 15th, 2006, 11:50 am

I am about to do the same thing you are. The oil pressure sensor is located on the oil filter housing. If you are using an electric gauge that is the place to put the oil pressure sending unit that will come with your new gauge. It you want to keep the stock sensor you will need to buy a "t" fitting. The only problem i havent answered before i can install mine, is what is the thread and pitch where the sensor screws in. I have been told it is not the standard 1/8 or 1/4 npt that comes on most gauges.

Nate

hoffman_BMX89 · Post by **hoffman_BMX89** » October 15th, 2006, 11:52 am

you will have to take out your stock oil presure switch and replace it with the one that came with your gauge

1992blazeredgs · Post by **1992blazeredgs** » October 15th, 2006, 12:23 pm

As i said, you will need to remove the stock oil pressure sensor, either directly screw the new oil pressure sending unit from your new gauge into that location. Most people say you need an adapter because the thread and pitch of that hole is not what comes standard on most gauges. Doing it this way your stock dummy light will no longer work. Or you can use a "t" fitting and screw your stock sensor in one end and the new oil pressure sending unit into the other side. Sorry i was not clear enough earlier.

Nate

PATDIESEL · Post by **PATDIESEL** » October 15th, 2006, 8:27 pm

The thread pitch does not match b/c the 1/4 inch fitting is standard and the K series motor uses metric fittings. You'll need an adapter and the yeasy way to tell the thread pitch is to check the threads on the stock oil pressure sending unit. I think it was a 10.0 or 10.25, but cannot remember which it was. Make sure to use some rubber O rings as gaskets or it will leak on the header and smell like crap as well as possibly running the oil level low. Do not overtighten the fitting into the head. The head being aluminum it will not take that much torque before it strips out and then you have a real problem.
I suggest taking out the radiator before you start the install. I found mine almost impossible to get to with the radiator still in the car.

kdogg233 · Post by **kdogg233** » October 15th, 2006, 9:55 pm

ok thanks alot for the help ill have to get under the hood tommorrow and check it out. If i were to just disconnect the dummy light with that cause the check engine light to come on?

slimmyslim1420 · Post by **slimmyslim1420** » October 15th, 2006, 11:42 pm

If you use a mechanical gauge where does it go? Do you still have the same problem with fittings and such?

max kl · Post by **max kl** » October 15th, 2006, 11:45 pm

yes its the same

PATDIESEL · Post by **PATDIESEL** » October 16th, 2006, 12:46 am

I do not suggest a mechanical guage. It sends oil all the way to the guage inside the car and thus if you have a leak inside you have a huge mess and a potential fire. Ever seen oil burn? It is almost impossible to put out and thus a fire would likely mean the end of your car.

Si1verBullet · Post by **Si1verBullet** » October 16th, 2006, 8:15 am

The mechanical gague is a real PITA to fit nicely. It uses a capillary copper tube instead of a wire to send the oil pressure to the dial. This locks together with a olive fitting.

Leaks from over tightning/under tightning are common, if you over tighten it it will break the oilve and then you need a new tube.

The capillary tube is a right pain to run as it cannot be kinked and rattles against everything under the dash as it is directly connected to the engine and vibrates with the harmonics no matter how much you damp it.

I think Pat is slightly over playing the fire risk. The PITA factor is much higher. Take it form someone who has been there and done that - electrical guage every time.

PATDIESEL · Post by **PATDIESEL** » October 16th, 2006, 3:19 pm

Auto Meter uses a nylon tube that doesn't rattle with their mechanical guages. Yes I am giving a worst case scenerio, but it is still a concern. Just not worth the risk for the slight extra cost of a electrical guage.

Tunes67 · Post by **Tunes67** » October 16th, 2006, 3:36 pm

For a street car.. an electrical oil pressure gauge is fine. For consistant race applications.. mechanical gauges (oil pressure & coolant temp) are a far better choice. They are more reliable and typically more accurate. However.. they are often more difficult to install. Mechanical coolant temp gauges usually have a limited reach.. so your usually forced into a dash mount. Or you have to special order one that will have a long enough lead to mount in a gauge pod on the A pillar.

Running a nylon or copper tube for your mechanical oil pressure gauge can be annoying and I agree that for a street application.. is not real neccessary. However.. just so you know why mechanical are superior to electrical.. Electrical gauges can fail in two ways where as mechanical can fail in just one way. With eletrical gauges.. the sensor or the gauge could malfunction.. and distort readings or not give a reading at all. With mechanical gauges... assuming correct and proper install.. its only the gauge itself that fails. Why is this better? In racing applications.. if your oil pressure reads 0 when you start your engine... and you have a properly installed mechanical gauge.. then you know beyond a shadow of a doubt that you have 0 oil pressure. Its not a sensor.. its in the engine.

This has been a subject of debate for a LONG time. Back in the 80's.. you wouldnt find anyone serious about their rides having an electrical set of gauges in their cars. Today.. gauges and sensors are much better made than they were back then. And for street applications.. they make our lives much easier. I will be running an electrical water temp and oil pressure and vacuum gauge inside the interior of my GS on a A pillar gauge pod. Inside the engine bay.. I will have a mechanical oil pressure gauge (since I have one laying around) installed as well. Mainly for initial startup. Cheers

Tunes67