Jeff's Technology Weblog

Replacing the timing belt and related items has been on my list of things to do and I finally got around to it this past weekend. While doing the timing belt, it made sense to also install a new water pump, replace a leaking front crank seal, replace the cam shaft seals, and put on a new valve cover gasket.

For this and many of the other typical tasks I’m doing, I use at least two sources of information:

1. Mazda Miata MX-5 Performance Projects by Keith Tanner
2. 1999-2005 MX5 Workshop Manual from Mazda

Tanner’s book is very good and is great for getting the lay of the land before doing the job. And the Workshop Manual from Mazda is a critical resource though it is designed for the professional and not the enthusiast.

Another book that would be useful for most folks (highly recommended!) is Mazda MX-5 Miata 1.6 Enthusiast Workshop Manual or Mazda MX-5 Miata 1.8 Enthusiast Workshop Manual by Rod Grainger. Unfortunately, the 1.8 manual is currently out of print on Amazon but may be available on the publishers web site. I’ve not used these resources because even though a 1999 MX-5 is a 1.8 because the 1.8 manual doesn’t cover the 1999+.

Two supplemental resources for any Mazda work, especially for Spec Miata, is the invaluable Spec Miata web site forums and the helpful Miata.net garage. The Miata.net garage has helpful instructions on most common tasks (e.g. timing belt change). And the Spec Miata forums cover many issues specific to race car prep.

In doing my timing belt change, I started off by removing the radiator. This isn’t strictly necessary, but it sure is nice to have the room. And radiator removal is one of the easiest jobs you can do on a Miata. In fact, draining the radiator fully of water/coolant probably takes longer then removing the radiator fan and related items. So I highly recommend doing this.

Takes up a lot of space -- get it out!

Once the radiator is safely out, the fun begins. Dis-assembly goes fairly quickly if you’ve already removed the A/C and power steering components. I started with:

1. Air intake
2. The valve cover gasket

As every component is removed, the parts go into separate labeled plastic bags. It is even better if you take photographs both before and after removal in case you need to refer back to what goes where later on. As this job progresses, there are a few brackets and cables to disconnect. Photographs are very helpful for quick reference if you get stuck the many hours later during re-assembly.

Valves

With the valve cover off, I moved on to removing the covers for the timing belt and pulleys to get access to the water pump.

Room to Work

With all the work to do related to a timing belt change, the water pump is itching to be replaced too. And it is a pretty simple task compared to the overall job.

Please Replace Me

Replacing the water pump was a real breeze. Unfortunately, it was not a sign of more good things to come.

Shiny

My leaky crank seal was next on the agenda and didn’t look to be such a daunting task. But it was mildly annoying due to the composition of the crank seal.

Trouble Lurks Within

Tanner’s book suggests using a seal puller, but this did not work at all. The seal on my car was rubber over a metal ring. The seal puller simply scraped the rubber off the ring and left me with a bigger problem to tackle. On the other hand, the Mazda manual suggests a screwdriver cover by a cloth. This turned out to be much more on target. With some measure of bad language and dark thoughts, I was able to finally get the seal out and the new one in.

At this stage, I went into a time warp and forgot to take pictures until I had the new timing belt on and was part way to putting the whole thing back together. Everything seemed to be going very nicely.

Almost Done?

So Very Close

Alas, it was not to be. Upon firing up the car, well, there was no fire. Despite my careful approach to putting on the timing belt, everything was not aligned properly.

I am fairly certain the crank shaft started at top dead center but moved on me when I was fiddling with the cam shaft belt alignment. So off everything came (sadly) and I was back to getting the belt put on properly.

The second time around seemed to go better and I was meticulous about checking everything once, twice, and even three times. After it was all reassembled for a second time (or was it third?), the engine fired up straight away and sounded great. I ran it for a while checking carefully for leaks and other issues. Everything looked good, so I took it out for a short drive.

3rd Time is the Charm?

On my short test drive, the engine ran smoother then it had in the past and things looked good. I took it back to the garage and again checked for leaks or anything unusual. No leaks were observed, so then I went out on a longer run into the mountains.

On my mountain drive, I pushed the car HARD. No issues were apparent for the first 10 miles. Then suddenly, I got some engine misfires. The tach was seriously bouncing and the spark plug firing was cutting out. I eased off and drove home another 5-6 miles without any further issues.

Upon arrival back home, I downloaded codes from the car using my ODB-II reader. Pending codes were reported as P0339 (crankshaft position sensor intermittent) and P0302 (cylinder 2 misfire). The Miata workshop manual suggests a P0339 is caused by loose wiring harnesses, so I centered my debugging in this area.

I rechecked all the wiring harnesses and didn’t find any issues. However, I did find a loose metal bracket that was dangling around. It seemed like this could potentially interfere with the sensor readings since it appears to be based on signal generation as metal passed through a magnetic field. I quickly removed the offended bracket since it was a remnant from my removed power steering pump.

Again, I took the car out for a long run and was hopeful. It was not to be. Again, I encountered misfires but later in my drive.

At this point, I have re-checked the cable connections but don’t have any strong leads. Since I was pushing the car very hard in steep terrain, I suspect there may be some heat related issues. But for the moment, I’ve got many other tasks to work on and am going to wait before running through the full set of diagnostic procedures suggested by Mazda.

All-in-all, this set of tasks (seals, belts, gaskets, etc) was more time-consuming then challenging. Of course, maybe I’ll change my tune if I can’t find the solution to P0339.

Let’s face it: a removable steering wheel is just plain cool. And very racy too. But for me, it also has a practical side.

At 6′3″ tall, a Miata is a tight squeeze for me. The stock Nardi steering wheel in my 1999 MX5 was right up against my legs and made it un-fun to get in & out of the car. Furthermore, it was also just too big and interfered with my hand movement while driving. Putting in smaller and removable wheel was designed to solve both of these issues.

The steering wheel I chose to go with was the Italian-made 290mm Personal Steering Wheel. This is a nice-looking wheel and has a good feel to it. I picked up both the wheel and hex hub assembly from Advanced Autosports.

Personal 290mm Steering Wheel

For comparison sakes, here is a photo of the new wheel size set next to the Nardi stock wheel.

New vs. Old

Installation of the hub assembly and steering wheel fairly straightforward — with one exception. If you look at the above picture, you’ll notice there are no bolt holes in the steering wheel. In order to attach it to a quick release hub, it is necessary to drill through the wheel.

My first task in drilling was to construct a template and to tape it to the wheel. I used cardboard for my template and marked it with the bolt hole references points by: 1) using a black poster market to apply ink to the surface of my quick release hub, 2) “stamping” the quick release hub onto the cardboard in order to transfer the ink to the cardboard, 3) carefully taping the template onto the steering wheel (properly centered onto the handily marked point on the wheel).  All of these items must be done VERY carefully in order to have the wheel properly mounted and centered on the steering column.

Once I had the template affix, I was ready to start drilling. I used Blu Mol drill bits designed for metal to make the bolt holes. The wheel itself is fairly soft metal (aluminum) and was pretty easy to drill through. Once done, I here’s how my wheel looked…

After Drilling

Next up was removing the old steering wheel. I had already done this previously during a dash dis-assembly, so it was pretty easy going. The first step is to release the airbag by removing a couple of bolts in the side of the plastic surround just behind the wheel. The airbag removal should be done only after disconnecting the battery (to avoid any nasty inadvertent airbag deployments).

Airbag Removal

After that, the wheel can be taken off by removal of the center nut and pulling hard on the wheel (with even pressure from both sides of the wheel).

Wheel Removed

After the wheel is off, there is still some removal work to do. The surround on the steering column must be removed (3 screws under the surround) in order to remove the turn signal deactivation assembly (the bit with the yellow label). The turn signal deactivation assembly is easily removed by taking out another three screws and disconnecting the electrical connections.

Almost Ready for Installation

At this point, I was almost ready to go with installation but had to trim a bit of plastic from the white plastic material around the column that spins freely in order to deactivate the turn signals. I decided to trim rather than remove this part since it didn’t look like it would do any harm for it to stay and yet looked like a pain to remove.

The first part of the hub that goes on should be put on with consideration for how the wheel will be aligned when the wheels are straight. I did a mock assembly to determine the proper orientation of this piece. Once placed on the attachment point, the center locking nut is re-installed.

First Step in Hub Assembly - Get the Placement Right

Next up is attaching the ugly-looking hex head.

Looks ugly but is solidly built

After this bit is on, you can put the quick release unit on to see if things are aligned properly. It may take one or two tries to get things right.

The final step is to bolt the quick release to the steering wheel and then the quick release mechanism to the column.

Final Step?

You’ll notice in the picture above that the wheel isn’t properly bolted in. In fact, it certainly isn’t safe to drive this way. The reason for this is that the wheel/hub don’t come with the necessary bolts to attach the wheel (annoying!). And why doesn’t a $100+ hub and $200+ wheel come with <$1 worth of bolts? I don’t know, but it sure is annoying.

Anyway, I’ve been told by Dave from Advance Autosports that the bolts should be 5/16″ coarse thread. I’ll be picking these up on the way home from work and finishing up the job later today.

Edit: 5/16″ coarse thread it is. My wheel is now properly bolted to the quick release mechanism.

It has been a very busy last few days in my garage. Over the weekend and last night, I completed the following items in my Spec Miata build project:

• Replaced the water pump
• Replaced the timing belt
• Replaced the accessory belt (drives alternator and water pump)
• Replaced the cam gaskets
• Replaced the front crank gasket (it was definitely leaking previously)
• Replaced the valve cover gasket
• Finished installing new coolant hoses (lower)
• Replaced the shifter boot (old one was thrashed)
• Installed a new, removable steering wheel
• Replaced the coil pack

I’ve got lots of pictures of the timing belt work and steering wheel installation. I’ll be posting those as I find time.