Help with presumed clutch master cylinder issue

[gregoryahunter1]

I have finally got my project 1998 V70 t5 running and Ive done a couple of shakeout drives. It has a new clutch. Yesterday - as I pulled into a gas station, the clutch pedal went to the floor and stayed there and the engine died (acting like the clutch was not pushed in.) The clutch pedal stayed on the floor - I was able to restart the car with the transmission in neutral, but couldnt get into 1st. The brake master cylinder had plenty of fluid in it. So i put my foot under the clutch to pull it away from the floor and suddenly - the clutch is working again. Able to drive it home fine

I assume this is a bad clutch master cylinder - or is there a way to tell if its the slave?

Are people just spending 200$ for a replacement master or is there a rebuild kit that is available?

Thanks is advance for any advice

Greg

[Grantkat]

Hey there, I can offer some generic input. I have some experience, though not on Volvo manual transmissions.

Determining which cylinder failed depends on where the fluid is (or isn't) going.
For the Master Cylinder (seems more likley)
Internal Bypass: The primary seal inside the master cylinder fails, allowing fluid to flow past the piston back into the reservoir rather than down the line to the slave.
Your "Pull Back" Fix: When you pulled the pedal up manually, you reset the piston and allowed it to gulp a fresh charge of fluid, which temporarily restored the prime.


For the Slave Cylinder
The Boot Test: Pull back the rubber dust boot on the slave cylinder. If it is full of brake fluid, the seals are blown.
External Leak: Usually, if a slave cylinder fails enough to drop the pedal to the floor, you will see a puddle on top of the transmission or dripping onto the ground.
Mechanical Bind: If the slave rod is bent or the pivot arm is cracked, it can hang up, but this rarely "self-heals" by pulling the pedal up.
Check the Floor: Peel back the driver’s side carpet. Look at the pushrod where it enters the Master Cylinder. If it’s damp or greasy, the Master is dead.

[abscate]

You have to pull the engine to get to the slave, it’s integrated into the release bearing.

On re-read

These can be a bit tricky to bleed. I would try pumping at least 250 ml of brake fluid through the bleeder valve on the slave cylinder adapter. Keep the brake fluid reservoir full while you do this! The clutch pulls fluid up pretty high on the reservoir.

[gregoryahunter1]

Thanks for advice. Will attempt on next day off