1998 Forester clutch pedal in "hot" Alaskan weather

[Ravenwoods]

We have a Forester S with 323,000 miles on it, and looks like it too. But the engine is still strong, doesn't seem to burn oil, but of course leaks oil.

New clutch put in about 150,000-160,000 Miles ago.

So the clutch is still strong. In past summers when we had lots of temps in the mid 80s or higher the clutch pedal would act strange. You could push it down but then need to pull it up again with your foot. So this only happens in hot weather and after the car has been driven a awhile and all the parts in the clutch system are thoroughly hot.  So yesterday was one of those days but this time it was worse. Almost impossible to get it into any gear when the car is stationary. Once you get moving then you can manage. 

And of course today when the car has cooled down the clutch is back to normal.

So there must be some need to make a clutch adjustment. When you have to pull the pedal back up, you can feel that a spring somewhere gives resistance about half way up the pedal stroke, then decreases after that point. It is almost like you have exceeded the springs correct depression.

Any suggestions on what to do?

[forester2002s]

I'm not familiar with a 1998. But if it has a hydraulic-actuated clutch, then the slave-cylinder may need replacing (located at the top-rear of the engine-block).

If it's cable-actuated, maybe the cable is sticking.

[Ravenwoods]

13 minutes ago, forester2002s said:

I'm not familiar with a 1998. But if it has a hydraulic-actuated clutch, then the slave-cylinder may need replacing (located at the top-rear of the engine-block).

If it's cable-actuated, maybe the cable is sticking.

It does have the hydraulic clutch with brake fluid in it.

[lmdew]

New hose and brake fluid.  Bleed it wall after the hose change.

[Ravenwoods]

10 hours ago, lmdew said:

New hose and brake fluid.  Bleed it wall after the hose change.

I'll give it a try.

[nvu]

Be careful adjusting the hydraulic clutch pedal.  The master cylinder rod needs to fully release when the clutch is all the way up.  There's a tiny hole in the master piston that releases pressure when it's all the way released.  This is to account for temperature changes and expansion.  When the clutch pedal is fully up, there should be some play in the pin connecting the pedal to the master cyl rod.

There's a spring in the slave cylinder that takes up the slack.  There's no pretensioning to adjust over time like cable clutches, the spring in the slave cyl self adjusts after every press and release.

It sounds like either there's air in the system from a bad slave seal or the hose is rotting out.  Also could be cracked clutch fork.

[Ravenwoods]

7 hours ago, Ravenwoods said:

I'll give it a try.

The "hose" is a steel hydraulic line, not a hose. Do steel lines go bad? 

[Ravenwoods]

1 hour ago, nvu said:

Be careful adjusting the hydraulic clutch pedal.  The master cylinder rod needs to fully release when the clutch is all the way up.  There's a tiny hole in the master piston that releases pressure when it's all the way released.  This is to account for temperature changes and expansion.  When the clutch pedal is fully up, there should be some play in the pin connecting the pedal to the master cyl rod.

There's a spring in the slave cylinder that takes up the slack.  There's no pretensioning to adjust over time like cable clutches, the spring in the slave cyl self adjusts after every press and release.

It sounds like either there's air in the system from a bad slave seal or the hose is rotting out.  Also could be cracked clutch fork.

My wife drove it today with no issues, and it was a bit cooler today, only about 80. Yesterday I did vacuum out the old fluid in the reservoir and put in fresh. Do steel hydraulic  lines rot out? We are in a low rust area so corrosion is generally not significant here. Wouldn't air in the system cause a problem even in cold weather? Wouldn't a bad slave seal allow fluid to leak out? And one would notice a drop in the fluid level? Before I vacuumed it out the fluid was still on the full line. No signs of leaks.

[GeneralDisorder]

The slave cylinders from that year range have a Subaru service bulletin about weak internal piston return springs. It causes the fluid to be displaced in the system - the pedal will not return to it's upright position and the slave piston will not retain pressure against the fork which causes insufficient throw of the fork and failure of the clutch to fully release. Also the rubber hoses always leak. Get a new NABCO slave cylinder and a new hose. Look harder - it has a steel line AND a hose. 

GD

Edited July 29, 2023 by GeneralDisorder

[idosubaru]

What he said. Replace slave cylinder and hose and prepare to bleed and bleed and bleed. Very common.
 

Or convert that unreliable maintenance required hydro clutch garbage to a maintenance free cable clutch and never think about it again. Granted I’ve never had a repeat hydro failure after I’ve replaced the slave and hose, but the fluid flushing and failure rates of the hydro components are trash on principle for no net gain. been so long I’m forgetting if the fork and ball are the same between the two or the cable swaps right in

Edited July 30, 2023 by idosubaru

[el_freddo]

Clutch fork and the pivot point need to be changed if swapping from hydro to cable clutch or vice versa. 

Plus you need the clutch cable mount bracket on the gearbox, mods to the pedal box and a suitable hole in the firewall for the cable to pass through. 

Much easier to just maintain/replace components on the hydraulic setup as needed. 

And I’d argue that clutch cables require just as much maintenance as the hydraulic setup. 

Cheers 

Bennie

[Ravenwoods]

Problem has gone away with cooler weather. It only happened that one hot evening. With 323, 000 miles on it maybe the car will die soon! But the engine still seems so strong.