"Jayvincent" (jayvincent)
07/18/2020 at 23:22 • Filed to: Scion, tc, clutch, Hydraulics
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"Jayvincent" (jayvincent)
07/18/2020 at 23:22 • Filed to: Scion, tc, clutch, Hydraulics | 4
| 2 |
Toyota’s Clutch Master Cylinder degree to be specific. My son’s ‘ 05 Scion clutch pedal went to the floor and stayed there the other day. Fortunately it happened about 1/2 mile from home and I helped him limp it home in 2nd gear (strap tied to the clutch pedal to pull it back up after getting in gear - a trick I learned from -my- father 40+ years ago) and went in search of the wisdom of the internet gods. A quick exam confirmed it wasn’t something easy like the slave cylinder which sits right out in the open between the exhaust man ifold and the battery: it’s the clutch master cylinder, which toyata decided to bury in the most inaccessible place in the engine bay: behind the shock tower, under the windshield wiper motor tray, next to the brake master cylinder.
failed clutch master cylinder assembly
When I say “buried” I mean you could’nt find it with a map and bloodhound.
intake pipe removed for access, brake reservoir at right
See the brake reservoir? It shou ld be right next to that... but it’s about 6 inches further to the right and back: the silver thing way off in the distance in the next pic is what I was after. Once you find it, you have to disconnect two hardlines by feel with ~15° of swing on your open end wrench (seriously need to get some flare nut wrenches if I’m going to pursue hydraulics routinely).
brake reservoir on right, clutch master cylinder is the grey shape in left way off in the distance
After that, you still need to remove your spine and fold your self under the dash, where you have to remove 2 nuts, again by feel because they are hidden inside a bracket pocket and detach the pedal linkage. I dropped the cotter pin of course... and it went behind the carpet, so I spent ten minutes chasing it along the firewall and floor pan until it got caught in the underlayment. Where was I? Hopefully you have a helper (I did - son’s car!) because you need hands on both sides of the firewall to extract the master and insert the new one. The n just reverse the process (i.e.: put t he blind nuts back on the studs by feel, drop the cotter pin AGAIN, don’t forget to reattach the pedal linkage) and start refilling the brake reservoir. Did I mention previously there’s no access to the clutch master cylinder? Since you can’t access it, there’s no sepa rate fluid reservoir , it’s fed by a line from the brake master reservoir, so you need to cap it when you disconnect it or it drains the brake master and then you have to bleed both systems! I managed to cap the line and only lose a little in the switchover, so I only had to bleed the clutch slave which has a helpful bleed screw. Last was a post mortem on the failed master cylinder. Sure enough, there’s a tear in one of the directional seals, right where it rubs on the machined port.
old piston with tear on the seal on the left
I could have bought a rebuild kit, but without knowing the failure mode in advance, I chose to go with a new assembly. No core return either, so I guess I can keep it in my parts bin of shame. Hope you enjoyed hydraulics Master Cylinder seminar 101 as much as I did.
pip bip - choose Corrour
> Jayvincent
07/19/2020 at 00:09 |
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Next thing to fail will be the master cylinder
Dr. Zoidberg - RIP Oppo
> Jayvincent
07/19/2020 at 02:22 |
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A decade ago, my slave cylinder failed on my ‘89 pickup and it was basically undrivable. I would top off the reservoir to limp home until the new fluid bled out . My brother in law tried to teach me rev matching as a way to get around. I definitely did not pick that up quickly. He then hopped a curb with the truck in lieu of a lift or jackstands and crawled underneath and began cursing for over an hour. But he replaced it and it was good as new.