The hotter the weather, the more I can't use first gear

This issue with my 2003 Mazda Protege 5, manual transmission, has been going on for years. I’d like to sell the car, so I’d like to fix it.

On occasion I am unable to shift into first gear from a stopped position. This never happens in the late fall, winter, or early spring - it all seems to depend on how warm it is outside. It is always fine at the start of the trip, but becomes a problem in what seems like a period of time proportional to how warm it is outside. Again, when its cool outside, it pretty much doesn’t happen. But once we pass 25C / 77F it is common, and will almost certainly happen on any trip of over a 10 minutes. The hotter the weather, the faster it shows up as a problem.

If I leave the car and come back after it cools down, first gear works fine again. And I can downshift into first gear as I come to a stop with no issues - I just hate riding the clutch like that, so I’ve been starting in second gear instead.

Any ideas?

Check the clutch master cylinder fluid level and the transmission oil level. Adjust the clutch master cylinder push rod free play.

I’ve been told that the clutch works off the brake master cylinder. Does that make sense, and wouldn’t I see issues in the brakes if it was the problem?

There are 2 master cylinders. One for the clutch and another for the brakes. Have you checked the fluid level? Have you checked the oil level in the transmission? Have you checked the free play at the clutch push rod?

“I’ve been told that the clutch works off the brake master cylinder.”

The clutch system shares the same fluid reservoir as the brakes.
has the brake/clutch fluid ever been changed? If not I’ll be it looks pretty dark.

IMHO this is a classic case of a bad clutch master cylinder.
I recommend you replace the master and slave cylinders. They’re not very expensive.
Empty (I prefer to siphon with a small flexible hose) the reservoir and fill with fresh fluid.
Bleed the brakes of old fluid as well as the clutch.
Going forward replace the fluid every 3 years, 2 years if you have ABS.

I had a manual transmission with balky shifting. A change of the transmission fluid solved it.

Maybe next year they’ll put a reset button in cars. Just press it from the comfort of the driver’s seat and everything on the car will be back like day one.

The clutch master cylinder is being effected by heat.

As the master cylinder heats up from the engine heat, the bore in the master cylinder expands to a point where the seals are no longer sealing in the bore. Then there’s no hydraulic pressure produced to operate the clutch.

You can easily check if this is the problem by carrying a bottle of water in the vehicle. The next time you can’t shift into gear, open the hood and pour the bottle of water over the clutch master cylinder. If you can now shift into gear, replace the clutch master cylinder.


My Google-fu has failed me in educating my ignorant brain on where in the engine compartment this part would be found. I can only find lots and lots of diagrams with no index of the labels :slight_smile: Any tips?

Open the hood, and look on the firewall in front of the drivers position. You’ll see the brake master cylinder. Next to the brake master cylinder you’ll see the clutch master cylinder.

Here’s what it looks like.


You’ll see a hose running from the top (white fitting in Tester’s link) of the clutch MC to the bottom of the brake fluid reservoir.