So let me first explain what happened to my car, then I'll tell you what I THINK happened, then we'll see if you guys agree.

 

I got stuck in very heavy traffic on the way home the other day. For you Seattle people, I was in stop&go traffic on Montlake Blvd. all the way from the U-Village to 520, and then stop&go from 520 all the way across the bridge. What this boils down to... is that I was in stop&go for about an hour and a half, solid. 1.5 hours of nothing but slipping the clutch while in first to creep forward a few feet at a time.

 

After about 50 minutes of this, my clutch started getting "softer". The clutch usually begins to engage at about 50% pedal, but now it was engaging at about 10% pedal. The clutch was fully engaged by about 20% from the floor. After an hour, my clutch was only using the bottom 20% of the pedal. I considered pulling over, but the car still drove perfectly fine (once I got up to speed, I felt no slippage of the clutch either). The clutch wasn't popping all the way back out (as it was fully engaged at about 20% pedal).

 

I was really worried something was wrong with my clutch, but I finally got clear of the traffic and drove in 5th gear for about 15 minutes without shifting. This seems to have helped, because after that, my clutch was back to normal.

 

What I THINK happened, is that the fluid in my clutch or something somehow got really really hot, causing the clutch to malfunction slightly. Do you guys agree with this? Any other ideas what happened?

 

1. If this is what happened, is this normal?

2. Is this something to be worried about occuring in the future (I've owned the car several months, and this is the only time it's happened).

3. Is there anything I can do to prevent this?

 

Thanks for your help guys!

hmmm...im assuming this is hydraulic....if so maybe the master cylinder is acting up....?? what you think guys

what model and year car do you have......

Can't believe I left that out, it's a '98 Legacy GT wagon, so yes indeed it's a hydraulic clutch

That's why auto tx's are good in the city.

 

Move, I hate frikkin' traffic!!

Yeah, I'm more inclined to say there is a small problem with the master cylinder not holding the pressure. You can boil the fluid in brakes because the heat from the pads is transfered directly through the caliper piston to the fluid. In a clutch you've got the piston, then a long actuating arm, a bearing, and a pressure plate to transfer all the heat built up in the clutch back to the fluid. So I don't think it is really possible to boil the fluid, especially since the pressure the fluid see's is based on the back pressure of the clutch pressure plate, and not how hard you are pushing the pedal. I'd say small issue with the master from you holding the pedal in for extended periods. The problem went away because you started shifting normally with out holding pressure on the pedal for extended periods. The more you shifted normally the more it pumped back up until the pedal felt normal again.

 

Does that sounds reasonable?

 

Keith

It is really about time for a new master and slave by my thoughts.

My 99 did this a couple years ago and since there is a TSB on the slave, hose, and washers on mine I changed them. It still did not have good pressure so I changed the master and it has been perfect since.

When they get bad enought the pedal will stick to the floor and you have to pull it up with your toe. Of course this happened in holiday traffic for me, but I still got it home by pumping wildly when I needed to shift.

I don't think it overheats, I think it just gets air in it and won't pump as well when it is warm. You can often bleed a clutch and get by for a while, but the real fix is to replace the worn bits.

Cookie, this is interesting, any chance you could post a link, or cut & paste the text of the TSB?

 

Just curious of the specifics for possible future reference.

Cookie, this is interesting, any chance you could post a link, or cut & paste the text of the TSB?

 

Just curious of the specifics for possible future reference.

 

 

Actually, I remember reading this TSB when we had issues with the clutch in our Rally car. Same thing, the clutch was stuck to the floor and had no pressure. It was the master cylinder in our car that was bad.

 

Keith

I'll check the file when I get home. At the time I found it on the internet, maybe at the End wrench, but it was a while ago.

Yes it was Endwrench, I saw it too. My neighbor had this problem.

 

http://endwrench.com/images/pdfs/ClutchInfoWin04.pdf

Huh, so according to that, the Master Cylinder isn't the culprit, it's the Clutch Operation Cylinder.

Thanks for posting it Ferret. Work is tough at fiscal year end and we have a train schedule change so I am buried.

This problem escalated a tiny bit (it did it on the way home from work yesterday, which isn't any more heavy traffic than I face every day) so I decided to go ahead and order the parts listed on that service bulletin. 1stsubaruparts.com only charged me $69 for the slave cylinder, hose, and 2 gaskets.

 

Let's hope the problem is only with my slave cylinder and not the master cylinder!