CMC issues

[Kjweber]

Hello,
So, I just bought a 1996 Ranger, it’s a 2.3 with a 5speed when driving it home the clutch went “dead”. The clutch pedal doesn’t seem to be connected to the transmission anymore. When I went to check it, the quick disconnect line was not connected. So, I put that back in and it still wouldn’t bleed. After some research on the forums I believe that with the quick disconnect, disconnected the pedal should be incredibly stiff. But that’s not the case. I feel like the CMC has gone bad but wanted y’all’s thoughts before I started throwing a buck of money at it.
Thanks,
Kevin

 

[don4331]

Is there fluid in the reservoir (under hood, close to the brake reservoir, on firewall).

With line disconnected, clutch should be solid. If you get air in master is if PIA to bleed - angles are wrong to get last pocket of air out. IMHO, they need to be bench bled, then reinstalled...

 

[Kjweber]

The reservoir is full. And when trying to bleed it does not build pressure (with the quick disconnect connected or not).

 

[4x4junkie]

Indeed these things can be a bear to bleed. Bench bleeding is the book method how it's supposed to be done. I would think vacuum bleeding could work too, though I've never tried it.

I have often had success by cracking open the bleeder screw just slightly, and then slamming my foot on the clutch pedal repeatedly as hard and fast as I possibly can for about 8-10 strokes (the quick violent slams being enough to dislodge the air bubbles and get the fluid flowing). If you can get just enough of a pedal that will allow you to drive it, any last tiny bit of remaining air should work its way out. A few others have reported failure with this method though. There probably is a specific technique to it (or maybe some dumb luck is involved, I dunno). Can't hurt to try though... YMMV.

 

[Kjweber]

Thank you. I’ll give that a shot!

 

[don4331]

The reservoir is full. And when trying to bleed it does not build pressure (with the quick disconnect connected or not).

If you don't have pressure with quick disconnect disconnected, you have master cylinder issue. With hose disconnected fluid has nowhere to go and pedal should be very, very firm.

 

[Kjweber]

If you don't have pressure with quick disconnect disconnected, you have master cylinder issue. With hose disconnected fluid has nowhere to go and pedal should be very, very firm.

This is what I’ve been thinking. I double checked that it wasn’t something stupid like the rod from the pedal became disconnected. I ordered a master cylinder as well. But I’ll probably still try to make sure it isn’t a bleeding issue. It’s unlikely since it was working fine then wasn’t but it’s worth double checking.

 

[4x4junkie]

If you don't have pressure with quick disconnect disconnected, you have master cylinder issue. With hose disconnected fluid has nowhere to go and pedal should be very, very firm.

If there is air within the master cyl, the air will compress and the pedal will still move.

 

[Kjweber]

A quick update. I think it’s fixed. I put a new master in. While bleeding it I found a “rubber thing” in the reservoir that I had to take out to bleed the new one. It was also in the old one. So, it may have just had a bunch of air in the system. I filled the old reservoir but it still had the “rubber thing” in it and I just assumed that was part of the container (since it came that way).
Best, Kevin

 

[alwaysFlOoReD]

A quick update. I think it’s fixed. I put a new master in. While bleeding it I found a “rubber thing” in the reservoir that I had to take out to bleed the new one. It was also in the old one. So, it may have just had a bunch of air in the system. I filled the old reservoir but it still had the “rubber thing” in it and I just assumed that was part of the container (since it came that way).
Best, Kevin

That rubber gasket is to allow fluid to get lower as brakes are used up, and to stop the air from contacting the fluid. The first time I owned a newer f150 that got me too, thinking it was part of the bowl, when it actually got sucked down from a leaking slave cylinder.

 

[franklin2]

A quick update. I think it’s fixed. I put a new master in. While bleeding it I found a “rubber thing” in the reservoir that I had to take out to bleed the new one. It was also in the old one. So, it may have just had a bunch of air in the system. I filled the old reservoir but it still had the “rubber thing” in it and I just assumed that was part of the container (since it came that way).
Best, Kevin

I have had that happen to me twice on the larger trucks. That rubber thing is black and it gets stuck perfectly to the top of the reservoir. You do not know it's there. And it has some depth to it, so you fill the reservoir with fluid, but you are only filling the rubber thing up, the master cylinder pump underneath is still dry. The only way I discovered it was being suspicious, and sticking a pencil down in the fluid and finding out it was not going all the way to the bottom of the reservoir.

 

[Kjweber]

Should I put it back in? Or is it just for shipping?

 

[franklin2]

The same thing is installed in the top of some of the brake master cylinder lids. It keeps air out of the fluid. If for some reason the fluid level drops in the master cylinder or clutch master cylinder, air has to replace the fluid. But instead of air, the rubber piece in the cap moves down instead, keeping the air separated from the fluid. That is what its for. Brake fluid likes to absorb water, they are trying to keep the moisture in the atmosphere from getting in the fluid.

I would keep it, just try to remember it's there so it doesn't fool you.