Bad clutch master cylinder?

I have a 2000 toyota tacoma and the clutch pedal has never come all the way back up after shifting gears. I just changed the slave cylinder in hopes that would help and it didnt. Now im thinkin it may be a bad master cylinder? What are some signs that it is bad?
The fluid was very dirty and there seems like there is a lot of sediment in there. I used a vacuum bleeder and bled the crap out of it. The pedal still acts the way it always has except this morning the clutch pedal was all the way depressed.
Any thoughts?

Very possibly a bad master.

Quite possible. I had to replace it on my 1979 Toyota 4X4, after about 25 years.

I had to replace mine on my '87 Toyota pickup. It was cheap. It leaked. I’ve never had dirty clutch fluid: what would make it dirty?

Mainly the deteriorating rubber. Moisture in the air can be a factor, too.

Why would that happen? I haven’t changed my clutch’s fluid since I changed the cylinders. It wasn’t dirty then, it isn’t now.

I don’t recall much in the way of sediment in the fluid when I replaced the clutch MC. It just needed a new or rebuilt MC after about 25 years. The truck had lived in IN and WI, so subject to temperature and humidity extremes. It also had sat undriven and rusting for at least a couple years when I bought it for $100. A few years after I got it back on the road and functioning well, the MC showed signs of failure. I was able to drive it the 300+ miles back home and do the job there.

Things do wear out over time. Im pretty sure its the stock cylinder as well, with over 220k on it

Correction: the clutch MC in my 1979 Toyota 4X4 truck failed after about 15 years.

Mine is gettin old too. Almost 20 she is. Great trucks tho!

You’d need to check your owner’s manual. Most have a recommend mileage/age to inspect the fluid. (They test for water, level and cleanliness.) My former car recommended 12 months, with mandatory replacement at 60K/5 years. Fluid moisture testers are as cheap as $10.

The system isn’t vacuum sealed, and brake fluid absorbs water. “Dirt” is a combo of wear and deterioration of rubber, as well as from heat (mostly in brakes). Excess water in the system can rust components. No auto fluid lasts forever.

I do check in accord with the manual. That’s how I know it isn’t dirty.

Do you check water in the fluid? It can be perfectly clear and need replacement.

No. That isn’t in the manual. And I asked about dirt. Not that checking for water isn’t a good idea.

It’s probably in the maintenance schedule, “Inspect fluid” vs “Check fluid level”. The Op’s truck, for instance, has a level check at 1 year, inspection at 18 months, if the Toyota dealer’s website was correct.

A lot of people are driving around with grimy master cylinders. That grime came from somewhere. It doesn’t really matter where it came from. It’s there, and if they’d changed brake fluid regularly it wouldn’t be.

Change your fluid every 3 years or change your master every 10. Up to you, but the second choice carries with it the risk of brake failure in the interim.

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What would be some symptoms of a bad cylinder?

And just a refresher. Its a clutch im talking about.

Same difference. The systems work the same way and in some vehicles the clutch and brake systems share a common master cylinder.

One symptom is the clutch not coming back up after shifting gears. :wink:

I’d also just for fun make sure the clutch pedal return spring was in good working order.

I bought the truck used and when i bought it the pedal would come back up about an inch short of all the way. The first thing i checked was the return spring and it seemed to be ok.
Now that i changed the slave cylinder the pedal will stay all the way down when i drove it last.

The fluid was very dark and a lot of sediment was in the fluid reservoir. I changed the fluid completely but am now thinking the seals inside the cylinder are bad, and or going bad.

It seems to be shifting ok except the inch or so that the pedal doesnt come back all the way up.

Also it really chatters and makes all kinds of racket only in reverse. I think the throw out bearing is going bad in the clutch assembly itself