Jeff's Technology Weblog

I finally got back to my Spec Miata project after a couple of weeks of inactivity due to work and travel. Today’s primary task was to replace the stock oil pressure sender. The primary reason to install an aftermarket gauge in the Miata is that my 1999 stock gauge doesn’t indicate true pressure. Instead, it simple indicates if there is or is not oil pressure.

Getting the stock pressure sensor out of the engine block is a little bit of a pain due to the inaccessibility. But using a 24mm deep socket and some patience is rewarded. The stock pressure sensor can only be seen with the engine removed or from underneath the car looking. However, removal of the sensor is best accomplished from the top of the engine compartment reaching under the engine block.

The following picture shows the location of the sensor above and to the left of the oil filter.

Replacing the stock sender with a remote sender

For my needs, I installed  a remote oil pressure sender relocation kit from Advanced Autosports. Using this kit, you can reconnect the stock sender and also add the aftermarket gauge connection to the new port. It is important to use high-temperature thread sealant on the fitting that goes into the engine block. You can pick this up at most auto parts stores.

Multi-port with stock sensor and aftermarket gauge tubing

For my application, I chose an AutoMeter 4421 2 5/8″ mechanical gauge. I mounted it in my radio plate next to my water temperature gauge. Note that you will also need to do some wiring into the fuse panel for gauge lighting (if desired).

Oil pressure gauge (on the right) with water temperature gauge

If you are reasonably proficient, then this job only takes a couple of hours.

Yesterday, I received some replacement thermostats I ordered from Amazon (yes!!, Amazon also sells auto parts). Surprise, surprise…the thermostat didn’t come with a replacement gasket. Anyway, I picked one up from the local AutoZone for $1.49 (you can get one cheaper at NAPA Online for $0.80).

Taking out the old thermostat is a breeze, but the real fun is in removing the old gasket. Getting rid of the old, stuck-on bits takes a fair amount of time. I sharp razor blade makes the job go faster.

Using/not using thermostats is a popular and controversial topic on specmiata.com. Some folks say don’t use them and others recommend various thermostat opening temperature levels. I’ve seen recommendations for 160F, 180F, and 190F thermostats. I ordered both the 180F and the 195F/91C. I chose to install the 180 since the 195 seems a little on the high side. The specs for my 1999 are initial opening temperature of 183-190F/83.5-88.0C and full opening at 212F/100C. We’ll see how things work out with the one I installed before trying any alternates.

FWIW, there’s a decent thermostat install DIY on Miata.net for anyone doing this project themselves.

Finally, an easy job!

Putting in a fuel sample port is required under the SCCA general competition rules (GCR). I did this quick task the other day and found it to be relatively easy task. I got my kit from SafeRacer ($80!!), but you can also pick it up from MiataCage.

The only gotcha in the process was that the kit didn’t include the proper number of hose clamps. It was two short which necessitated yet another trip to the local auto parts shop. One of the things I’ve found frequently with auto parts is that parts rarely include any needed, related items like gaskets and washers, so I find myself running to the local Kragen, AutoZone, or NAPA Auto Parts way too often.

With any project requiring fuel line modifications, it is crucial to check for leaks afterwords. You don’t want any nasty surprises when the engine is hot and there is a risk of a fuel fire. I’m trying to get in the habit of carefully monitoring for both fuel leaks and even brake line leaks since I’ve done a lot of work of both of these recently.

Anyway, here’s the final installed product: