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Mazda b2300 stalls when i push in cluch

I have a 2004 mazda b2300 4cyl 5 speed that wants to stall on me sometimes when i engange the cluch and all most come to a complete stop. It does not happen every time i do this, but some of the time. I am able to instantly restart the truck and drive just fine. Im just confused at what might cause this. I did a tune up to it this weekend, and the cap from the clutch fluid did come off, i dont know if this would have anything to do with it. The truck runs great, just wants to stall some times.

I’m having a hard time understanding the problem. A clutch WILL stall the engine if you try to come to almost a complete stop with the clutch engaged.

Imagine i am coming to a stop sign, with the clutch pressed down, and pushing on the break to come to a complete stop. The engine should not stall, this is when i am having the issue.

The problem might be with the Idle Air Control valve.

The IAC valve controls the engines idle when the accelerator is released and the clutch pedal is depressed.


If the clutch is bad or the fluid is contaminated, perhaps it is not completely releasing and the stalling is from the the car coming to a stop while the clutch is still partially engaged. Any problem shifting in and out of gear while the truck is stopped or while driving ?

no problems shifting at all. Everything worked fine on friday, then sunday it started dieing on me after i did the tune up.

Next time it does this, immediately shift it out of gear into neutral. If it is hard to pull out of gear, the clutch is not being disengaged. A fluid change may help, but you’ll probably need to chsnge the master and slave cylinders. If it glides out of gear easily, it’s most likely an engine problem, possibly with a slow or gunked up IAC.

This may be a little far out, but perhaps the motor mounts are bad allowing the engine to shift position when you depress (disengage) the clutch and in doing so is grounding out the ignition. One outstanding mechanic that took care of my car had a car come into his shop that would stall on right hand turns. The car had been to other shops and the other shops blamed the float in the carburetor. He found that a motor mount was weak and allowed the engine to shift so that it eventually wore the insulation off the primary wire to the coil and would ground out the ignition system. When the car stalled, it lost momentum and the engine would then cut back in. It was a stick shift car.

When was the last time you changed your spark plugs? And how many miles does it have on it?
If these are the original plugs, you problem MIGHT be as simple as the need for some routine maintenance.

Like i stated above, i just did a tune up on it this weekend. Changed Plugs, wires, oil, oil filer.

Sorry, I missed that.
But having gone back and read the post, have you gone back over your tuneup work?

yes, and actually i did notice something. There is a small hole in the cap that covers the clutch oil compartment. Very small, barely larger than a pin size hole, dont think that should be there. Could this cause some sort of vacuum issue?

That small hole on the clutch master cylinder cap is a vent hole.

If it wasn’t there, a vacuum would be created in the master cylinder when the fluid is displaced when the clutch pedal is depressed, making the clutch pedal harder to depress.


i guess ill take it to a auto shop and have them slap a censor tester and see if anything shows up. I hate to replace a perfectly good IAC and waste $50

You can test the IAC valve yourself.

The next time you go to slow down and stop, place the transmission into neutral

Now use your left foot to use the brake, while at the same time slightly step on the gas pedal with your right foot. When the vehicle is stopped, keep slightly stepping on the gas pedal see if the engine idles. Now take your foot off the gas pedal to see if the engine stalls.

If the engine stalls replace the IAC valve.


I went out and tried this, and it seems that the IAC valve is good. I was able to stall or “kill” the engine one time, but all i did was push the clutch all the way to the floor, hit the breaks slowly, and it died before i even started making a turn. There is a sensor attached to the clutch, i think it allows you to start the truck by telling the engine that the clutch is pushed down. Is there any way that this sensor could be the root of the problem, since it only happens when i push the clutch down? Thanks for all the advice you great peeps have given me so far.

Can you prevent the stall by quickly popping it into neutral, then clutch back out, then coming to a stop in neutral? Then, if you push in the clutch and it stalls, it might have something to do with that sensor (clutch switch). I have no idea why it would though.

im not for sure if i can prevent it like that or not, i will try tomorrow on my way to work, its getting past this old farts bed time.

Great name for this site: The Old Farts Club.

It could very well be the fault of the safety lockout. The switch is to prevent you from starting the car with the drivetrain engaged.