2009 Mazda 5 - Clutch hydraulic system needs regular bleeding - Slave cylinder leaking?

[Number_35]

I guess the title says it all, or at least most of it.

Perhaps three years ago the clutch started to feel weird, and then didn't want to return from the floor after being pushed in. This was during a very cold part of the winter, same time of year as now. I bled the slave cylinder, and was a bit surprised to see how much mushy partly crystallized ice/water slurry was in the fluid initially.

The clutch started to feel soft last fall, and I bled it again. No evidence of ice as it was a lot milder in October or November.

Now it's feeling soft again.

My first suspicion is that the slave cylinder is admitting air, and that the correct fix would be to change it out. I wonder if the freezing a few years ago damaged an internal seal. The bleed nipple didn't feel quite right either; it seemed like just a fraction of a turn allowed it to go from sealed to fully open. Perhaps some grease or sealant of some sort around the nipple threads would help.

But assuming that the problem is the slave cylinder, here are the options from Rock Auto:

What do you all recommend (or not recommend)? I'm willing to pay the highest price if the unit is good and provides good service for the next few years.

I'll phone the dealer too, but am prepared for the part to be pretty expensive.

I wonder, too, if the part is fairly universal - I think it would be identical to that used on the Mazda 3 and the Ford Focus equipped with a Duratech 4 and an MT.

Thanks in advance!

 

[michaelluscher]

OE Mazda part number is BP4S41920D

$80-$120US

Crossing that part number to RockAuto yields

 

[Number_35]

OE Mazda part number is BP4S41920D

$80-$120US

Crossing that part number to RockAuto yields

View attachment 90216

Thanks, Michael - it's interesting that your search (by Mazda part number equivalent) turns up some different parts than my search by RA's year/make/model algorithm.

 

[atikovi]

My first suspicion is that the slave cylinder is admitting air, and that the correct fix would be to change it out.

What about the master cylinder?

 

[Number_35]

What about the master cylinder?

The clutch and the brakes share the same master cylinder. The brakes seem good, so I suspect the clutch slave cylinder.

 

[atikovi]

The clutch and the brakes share the same master cylinder. The brakes seem good, so I suspect the clutch slave cylinder.

Well, Rock has a separate listing for them, https://www.rockauto.com/en/catalog...ansmission-manual,clutch+master+cylinder,1996

 

[redbone3]

Well, Rock has a separate listing for them, https://www.rockauto.com/en/catalog...ansmission-manual,clutch+master+cylinder,1996

I suspect they share the same reservoir. they could not share the same cylinder.

 

[Astro14]

The clutch and the brakes share the same master cylinder. The brakes seem good, so I suspect the clutch slave cylinder.

I suspect they share the same reservoir.

But the cylinder under the pedal is usually the master.

And the cylinder on the clutch is usually the slave.

edit: simultaneous post with redbone.

 

[atikovi]

Yes of course they get the fluid from the same reservoir, buy my point was why are you excluding the clutch master cylinder as the source of the problem?

 

[Number_35]

I suspect they share the same reservoir. they could not share the same cylinder.

I suspect they share the same reservoir.

But the cylinder under the pedal is usually the master.

And the cylinder on the clutch is usually the slave.

edit: simultaneous post with redbone.

Yes of course they get the fluid from the same reservoir, buy my point was why are you excluding the clutch master cylinder as the source of the problem?

Thanks, guys, good thought! I had not considered this.

 

[MRC01]

@Number_35 thanks for asking... this reminds me that I need to bleed the clutch slave cylinder on my Mazda3. Even though it's working perfectly, even if there is no air in the system, this is important to do periodically because brake fluid attracts moisture which causes corrosion. Most people do bleed the brakes but it's easy to forget to bleed the clutch too.

 

[MRC01]

Boy, the clutch is not easy to bleed on my 2014 Mazda3. It looks like it should be easy. But the screw you turn isn't a hex nut like you'd have for the brakes. It's not even made of metal, but some kind of plastic. It's shaped sort of like an ellipse with parallel sides 14mm apart. You can get an open end 14mm around it, but then you can't turn it because the spacing is too tight: the radiator fans are in the way. You can almost turn it by hand but not quite (maybe if you're a rock climber with ape-like finger strength). And you have to rotate it more then 90 degrees before any fluid comes out (even under pressure). I managed to get 3 bleed cycle squirts out of it with a helper pushing the clutch pedal. Clean fluid came out all 3 times, no air, water or dark rusty stuff. So the job is done and it looks like the clutch slave cylinder is in good shape.

To do it easily I'd have to buy a 14mm open-end wrench and cut the handle short to about 1.5" long. Just enough leverage to turn it but not long enough to get obstructed by the tight spacing.

 

[Number_35]

Boy, the clutch is not easy to bleed on my 2014 Mazda3. It looks like it should be easy. But the screw you turn isn't a hex nut like you'd have for the brakes. It's not even made of metal, but some kind of plastic. It's shaped sort of like an ellipse with parallel sides 14mm apart. You can get an open end 14mm around it, but then you can't turn it because the spacing is too tight: the radiator fans are in the way. You can almost turn it by hand but not quite (maybe if you're a rock climber with ape-like finger strength). And you have to rotate it more then 90 degrees before any fluid comes out (even under pressure). I managed to get 3 bleed cycle squirts out of it with a helper pushing the clutch pedal. Clean fluid came out all 3 times, no air, water or dark rusty stuff. So the job is done and it looks like the clutch slave cylinder is in good shape.

To do it easily I'd have to buy a 14mm open-end wrench and cut the handle short to about 1.5" long. Just enough leverage to turn it but not long enough to get obstructed by the tight spacing.

That's strange! Our '09 Mazda5's clutch slave cylinder is easy to bleed - good access, and just a conventional bleeder nipple with a hex flange - 9 mm IIRC.

 

[MRC01]

Yeah, my other cars have been much easier. With this one, the bleed nut has plenty of clearance left and right, while it's tight front and back. If it had a standard hex nut like a brake caliper then it would not be a problem since you could attach a wrench sticking out to the side. Yet it has this oblong nut shape and the only direction a wrench can be attached is if the handle sticks straight out front or back where there's no room for it. It's really stupid & frustrating.

 

[Cdn17Sport6MT]

Yeah, my other cars have been much easier. With this one, the bleed nut has plenty of clearance left and right, while it's tight front and back. If it had a standard hex nut like a brake caliper then it would not be a problem since you could attach a wrench sticking out to the side. Yet it has this oblong nut shape and the only direction a wrench can be attached is if the handle sticks straight out front or back where there's no room for it. It's really stupid & frustrating.

It's supposed to be turnable by hand. Surprised that it's so tough to turn...

 

[MRC01]

It's supposed to be turnable by hand. Surprised that it's so tough to turn...

It's not super tight, easy to turn with a wrench, but it's more than hand tight. If it were only hand tight, I wouldn't trust it to stay closed especially over time with vibration.

 

[Cdn17Sport6MT]

Just buy a cheapo 14mm, with, as you suggested, the intent to cut it down with say a grinder... 14mm flats, a good fit?