Weird Clutch Engagement Please Advise
 

Hope some of the knowledgable guys will chime in on this one.

Been bleeding and bleeding the clutch on this FD every other weekend. New clutch installed (Exedy Street - same as stock really with extra clamping force). Now, one thing I notice when bleeding from the slave is that I can never get a "steady" stream from the bleeder screw, even when using the power bleeder or mityvac.

Symptoms - after a period of time driving the car the clutch enagement seems to get progressively higher, to a point where the clutch is not engaging fully and starts slipping. Sometimes when driving there are no issues, but when letting the car sit at idle, or even shut down, after a while the clutch engagement point is up to the last - leaving me with no free play and a slipping clutch.

Any advise or suggestions as to what might be happening would be really much appreciated. Note new master and slave cylinder have been installed trying to eliminate this problem with no joy!

Are you using a SS clutch line? The OEM rubber one can't handle the additional pressure from aftermarket clutches and can cause the problems you are talking about.

When bleeding you did not run out of fluid?

I have been told that it can be a bi+ch to get all the air out if it finds its way in there.

When bleeding I use a mechanical vac pump and an inline transparent vacuum pot. Have a friend run the pump, and I man the master all the time keeping it topped off, and wait for the call that fluid is coming out clean and bubble free.

When it is bleeding you should definitely get a steady stream. If not there is air in the system and will exhibit symptoms like those stated.

Is it possible that one of the fitting in the system is loose? Has anything been serviced since this has been a problem?

When I installed my SS clutch line it did take some of the “mushiness” out of the pedal that the HD PP caused, but it shouldn’t get progressively worse, so I am assuming this is not your issue?

Engaging higher and higher is not a sign of air in the system. It is often a sign of a bad master cylinder (bad check valve or master piston not retracting far enough to open the return hole to the reservoir) not letting the fluid back into the reservoir as it expands with heat. Bleeding will only cure this until the next time it warms up.

I had a bad master brake cylinder on a Chevy Van that would lock up the brakes as things warmed up. The short-term solution was to "crack" open the brake lines and let some fluid leak out so I could complete my trip. A new master cylinder fixed it.

Dave

Now that would surprise the hell out of you!

Yeah - you'd be driving along and the van would start to slow down despite flooring the throttle. Didn't do much good for the brake pads or the wheel bearing lube either! Sure didn't want to drive like that...

Dave

This is my guess as well.

I'm actually seeing this problem with the brakes too (lock up). The clutch master cylinder is new (replaced) however I'm going to change this again and replace the brake master cylinder also. I don't have a SS clutch line installed.

ky7,

To my knowledge, Mazda doesn't sell any *new* master/slave cylinders anymore (I bought one a few years back and was given that info from Ray at Malloy). They are supposedly all rebuilt ones now. In that case, it's possible that you got a hold of a bad one.

On a related note. I am a noob at bleeding stuff and my clutch was bled by a friend of a friend of a friend kind of person. I have an ACT Street/Strip and it is really tough to get the car into gear, the clutch pedal is almost on the floor and the point of engagement is hard to find well not as precise as it was on my old FD however when you pump the clutch it gets progressively better but still nowhere near an acceptable driving level. Is this a bleeding problem?

Fair play for hijacking the thread dradon03! It sounds like you need to bleed the clutch properly. Lots of guys use speed bleeders to get the air out of the system. The shop manual procedure works, but I prefer to use a powerbleeder or mityvac.

Mahjik, hopefully I just got a bad one (clutch master cylinder). What's weird also as I say is the brake pedal gets progressively stiffer and the brakes start to lock up, particularly bad on the front.

Thanks guys, all very useful info as usual.

From the sound of it symptoms seem to arise at idle or shutdown. In other words when engine temps / fluid temps are elevated. The system seems to be building pressure, which DaveW had mentioned may be due to a faulty master cylinder.

What kind of brake fluid are you using and is it possible that the master cylinder is overfilled? It is unlikely that these items are the issue, but may be something to check for. If the master cylinder is overfilled the fluid can not displace into the reservoir, which in turn creates pressure. As far as fluid….well that’s a no brainer.

I don’t believe the SS line will correct the issue. The compliance in the stainless steel line should reduce losses.

In case you are wondering where to get them, I've gotten brand new OEM Tokico units from BAP/GEON. These were FC parts, though. Same thing Mazda would sell you. They likely have them for FD too.

I didn't want to mess around when it came to 20 year old brakes...

Thank you sir for answering me:) I am wondering my last mini hijack, I was going to order speedbleeders for the brakes what kind of a speedbleeder can I use for the clutch?

Thanks

Ok so I've been thinking on DaveW's and C's-7's comments.. and I took the car for a drive. 5 minutes into it the brakes we're dragging badly. Driving on, the clutch engagement started getting higher, leading to slippage.

I release the pressure from one of the lines at the brake master cylinder, going to the ABS, this temporarily released the "pressure" in the system and unlocked the brakes. I also cracked the line and released some fluid at the clutch master cylinder, and clutch engagement was back to normal.

I've ordered new clutch and brake master cylinders, in the hope this will resolve the situation. Any further comments on my conclusions from people in the know?

Thanks.

I don't understand why both the brake and clutch systems' returns would be blocked, unless they were both degraded by bad fluid swelling the rubber seals and causing the masters to not return. That seems unlikely. Is it possible for the reservoir to be overfilled and there is no where for the excess fluid (when it warms up and expands) to go?

Dave

I know Dave it's odd. I'm using an appropriate DOT4/DOT3 fluid. The reservoir is not overfilled, it's slightly under the full mark and I checked to see and there's ample room for expansion.. I'm gonna take the clutch master out tonight and see what the seals look like.

As I say, when I release some fluid by cracking the lines at both the brake master and the clutch master it 'alleviates' the problem..