Today's Miata mystery

I went to check on the Miata today since we got a little "spring preview" weather-wise today. It's been sitting in my neighbor's extra garage for the winter. I've been over to check it every month or so and, so far, it's been fine. About a month ago, I warmed it up, then put it in gear to roll it forward and minimize tire flat spots and then shut it down. No issues, nothing unusual. Today, when I went to start it, there was no clutch at all. The pedal moves, but appears to build NO pressure whatsoever. I checked fluid levels in the res and it's a little low, but not totally dry. I refilled it and, still nothing. I know these are well known for needing slave cylinders, but it seems odd that it would go from perfectly functional to totally ineffective in a month when it hasn't been used at all. Here's the weird part, I found 2 sockets and a flat-blade screwdriver under the car that don't belong to me or my neighbor. I'm kind of out of time and daylight, and I'll do a full assessment tomorrow if the weather holds. So what's your best guess? Random failure or was someone messing with my car?

I can see a marginal one going totally bad sitting, best practice to replace the master and slave together. One of you is probably just unaware of the missing tools that got dropped.

In reply to BrokenYugo:

The tools are the odd thing. I know the tools weren't there in December when I put the car away. I've only been in the garage a couple times to start the car and he said he hasn't been in there at all. Who knows, maybe it was old man Wilkins from the amusement park. Maybe I'll place a quick call . . .

Clutch master cylinder piston cup seal or slave cylinder piston cup seal worn or broken allowing fluid to bypass.

The slave cylinder in my old Mazda 626 failed a couple times, and each time the failure was pretty instantaneous - one time it worked fine, the next time I pressed on the pedal it didn't.

Believe it or not, I've only lost one slave in a Mazda and that was a 323 GTX. But it happened overnight. Easy to check.

Keith Tanner wrote: Believe it or not, I've only lost one slave in a Mazda and that was a 323 GTX. But it happened overnight. Easy to check.

I had one fail instantly -- drove the car to a meeting, went inside for an hour, came out and boom no clutch.

I just had the clutch slave die on mine, over about a day and a half. Fine one day, then the pedal was inconsistent, then it was toast.

I've had Mazda masters fail that quickly. They usually do.

However if there is an assist spring on the pedal (don't remember if Miatas have this or not) then the pedal will generally stay stuck to the floor if it's blown hydraulics.

BUT if your clutch fork or its pivot break/crack, you'll have fine hydraulics and no clutch action.

Have only seen this sort of failure happen with an upgraded pressure plate though.

It's my experience that a worn out master/slave gradually increases pedal effort before they die, happens slow enough you don't notice until one screws up and you change them out.

It's easy enough to check. Look under the car while someone presses on the pedal. If the arm doesn't move, you're looking at hydraulics. If it does move about 3/4", then you have something else going on inside the bell housing.

To confirm that it's the slave - the real weak point - pull the boot back on the slave. If it's full of fluid, slave.