Replacing starter motor

It's a 1992 1.6 model, in case that makes a difference!

Try doing a search on miata.net, including the mailing list archive and miataforum.com. Otherwise, Rod Grainger's Enthusiast Manual is less than $20 in the US, and it comes from the UK.

Leon

Hi Neil,

It's a challenge, to be certain. You need a lot of time, some dexterity and patience. This is a joke, but true: it's easier if the engine were first removed from the car.

I did mine on the '90 Miata (well, Eunos) at 131K miles (about 30K miles ago). The symptom was that, sometimes, when you attempted to engage the starter, all you got was a little "click" and no wurrrr, wurrrrr, wurrrr.

Being the thrifty sort, I realized immediately a few things:

1. The starter is just an electric motor which operates under what we call a short "duty cycle". This means that for most of it's existence, it is merely along for the ride, actually doing nothing but participating in the mass of the car. The only time it actually does something is when you start the car.

Even then, the motor itself doesn't see all that much stress and wear.

1. The thing that wears out is the starter solenoid. This is a massive set of copper contacts that engage when the solenoid (which is a kind of electromagnet) slams home. That's the "click" you don't really, usually hear because the wurrrr, wurrrr, wurrrr starts immediately. Without the wurrr, wurrrr, wurrrr, however, all you get is the "click". What the solenoid does is connect your starter motor directly across the battery so hundreds of amperes can transform themselves into the useful work of spinning your engine around. If this sounds dramatic, it is. The net result of this is that a hell of a lot of stress is applied to the contacts; over time, they carbonize and wear. We call this "burning out". After a while they don't work so well and need replacement. For me, it got to where the "clicks" won out over the "wurrrs" around 131K miles.

1. Real automobile manufacturers make the solenoid replaceable. Being a real automobile manufacturer, Mazda does this in the Miata. Realizing this, and this is where the "cheap" part comes in, I elected to buy the solenoid and not a complete motor. I figured I already had a motor that worked and a solenoid that did not. I also ordered a replacement set of motor brushes that were inexpensive ( or ) and I figured I would not really need. But if they were easy to replace, I would do that as well once the starter was apart. They weren't; what the shop manual didn't make clear is that new brush leads have to be welded in place. As I suspected, however, inspection of the brushes already in there indicated that the wear was minimal.

Having said all this, Neil, I have to admit that when I finally had the thing out and on the workbench, the thought of replacing it again any time soon was not all that appealing. For a brief moment there, I questioned if my cheapness was appropriate and would I be doing this again soon for some reason I overlooked.

Then I said the hell with it, put in the new solenoid, *Bench Tested It First*, put it back in and life has been swell.

Good luck,

Ken

Beware, removal may adversely affect performance. Cheers, Alf snipped-for-privacy@remove.the.obvious.ieee.org