Heavy clutch after freeway ride?

[Marc Lenssen]

Hi All,
At a cold start the clutch and power steering on my 2002 s60 t5 seem to work much lighter than after driving for a while on the freeway. Especially the clutch is quite a bit heavier to operate after coming off the highway and seems to stay heavy till a cold restart. Anything I should worry about?

Thanks,
Marc

[JamesT5]

Check your clutch and brake fluid levels before you look at anything else, you could have an air lock in the system.

[graemewelch]

a air lock wont make a heavy clutch

[JamesT5]

a air lock wont make a heavy clutch

Well it's always worth a look.

[Marc Lenssen]

Brake fluid changes have been done by dealer according to maintenance schedule. But I need new rear brakes anyway, will refresh the fluids at the same time then...does it make sense to move to dot 5.1?

[M-R-P]

I have dot 5.1 and I still get a heavy clutch after a long run. I think it may be something to do with the vacuum system for the brakes but it doesn't happen often so I'm not too bothered by it.

[Harvey]

I have dot 5.1 and I still get a heavy clutch after a long run. I think it may be something to do with the vacuum system for the brakes but it doesn't happen often so I'm not too bothered by it.

Very strange,there is no servo for the clutch pedal it could be just the heat in the engine bay but if the fluid got very hot the pedal would just go lower or lose the clutch?
Have you bled the clutch fluid at the same time you bit the brake fluid change ?.
Stribo has said the same when he went on the rollers,Claymore said its just heat thing ok when it's cools down.

[stribo]

Very strange,there is no servo for the clutch pedal it could be just the heat in the engine bay but if the fluid got very hot the pedal would just go lower or lose the clutch?
Have you bled the clutch fluid at the same time you bit the brake fluid change ?.
Stribo has said the same when he went on the rollers,Claymore said its just heat thing ok when it's cools down.

Our's just went low on the pedal, the bite point was right by the floor, had the same sort of thing at Shakespeare Raceway last year too, though the pedal wouldn't return to normal position, again, Colin said this was down to the fluid getting too hot, neither time has it got heavier, just lower. The fluid is going to be upgraded at its next service.

[Harvey]

Our's just went low on the pedal, the bite point was right by the floor, had the same sort of thing at Shakespeare Raceway last year too, though the pedal wouldn't return to normal position, again, Colin said this was down to the fluid getting too hot, neither time has it got heavier, just lower. The fluid is going to be upgraded at its next service.

Yes that makes sense if it just goes lower Being down to heat,then returns to normal when cooled down.

[Marc Lenssen]

Pedal travel on mine stays the same, it just takes quiet a bit more force to get the pedal down after a freeway ride.... or any longer ride for that matter...
The dealership did the last fluid change so I assume that they did a decent bleeding. But I need new rear discs and pads anyway for the MOT so I will do fluid refresh and decent bleed....Also wondered if the dot 5.1 might be the best option.

[LeeT5]

Yes that makes sense if it just goes lower Being down to heat,then returns to normal when cooled down.

Really, how? My understanding of all things material/liquid is when they get hot, they expand. Therefore, the pedal shouldn't go lower. Clearly, I'm missing something.

[stribo]

Really, how? My understanding of all things material/liquid is when they get hot, they expand. Therefore, the pedal shouldn't go lower. Clearly, I'm missing something.

I'm guessing if there's water in the fluid it'll turn to steam when it gets hot, so compressable.

[LeeT5]

Clutch pedal feel on S60R/V70R is known for being 'slightly' heavier than most hydraulic clutches, certainly, most other cars I climb into are or do seem lighter (not all thou).

For the record, I had my local Volvo dealer change my clutch and brake fluid all to ATE Blue 5.1 fully synthetic and I can concur that the clutch did feel slightly lighter than when I drove it in, although that could have been my perception down to my high expectations? One thing was clear, the brakes were super responsive and much more powerful on the new fluid. Does get some weird looks by garages thou if they look at the reservoir!!

As far as pedal travel is concerned, mine does not alter nor does it become heavy after a long drive on motorway or after a vigorous sprint up a dual carriageway either. the pedal feels the same and travel does not alter.

[LeeT5]

I'm guessing if there's water in the fluid it'll turn to steam when it gets hot, so compressable.

Commonly known as 'fade'. Yes that would explain. If the fluid is boiling then it will turn to gas. The answer is a full brake and clutch fluid replacement.

[M-R-P]

my travel doesn't change, just a heavier pedal.
there's no vacuum to the clutch but the clutch comes from the same reservoir as the brake, which has a vacuum system attached. a slightly leaking one way valve in the system coupled with prolonged pressure from a long drive could conceivably cause some sort of issue in the hydraulic system and since the vacuum is there to assist brake return, wouldn't show itself under braking but could effect the clutch.

all guesswork on my part but makes some sort of sense in my head.

[stribo]

Commonly known as 'fade'. Yes that would explain. If the fluid is boiling then it will turn to gas. The answer is a full brake and clutch fluid replacement.

Being done at the next service mate.

[Marc Lenssen]

Checked the check valve by taking the hose of the manifold and suck on it... check valve seems fine. The hose connecting to the manifold however felt fairly loose, fixed to the manifold wit the famous clampy crap. I could move the hose back and forth fairly easily. Time to replace them with some decent screwy clamps because it would not surprise me if I was loosing a bit of vacuum there...and order a check valve anyway...never hurts to be sure for 10 quid.. :-)
Keep you posted on whether this made any difference..
Marc

[Harvey]

Really, how? My understanding of all things material/liquid is when they get hot, they expand. Therefore, the pedal shouldn't go lower. Clearly, I'm missing something.

brake fluid is hygroscopic,which means is sucks up moisture which is why it should be changed every 2-3 years.
When it's gets very hot the moisture then turns to steam which inturn gives the long pedal when hot as the steam then has to be compressed before the clutch plate is is released or the brakes pedal goes long.

http://www.google.co.uk/url?sa=t&rct...Wak2hvYijq4rVw

[Harvey]

Commonly known as 'fade'. Yes that would explain. If the fluid is boiling then it will turn to gas. The answer is a full brake and clutch fluid replacement.

Brake fade is when the disk & pads go above there working tempture for the pads.

Brake fade should not be confused with Fluid vapour lock.

[stribo]

As I understand brake fade, when the brakes get too hot, a gas is released(I'm guessing from the pads), which forms a cushion between pad and disc, decreases brake performance, not unlike what happened to the C70 brakes at Trax, though I think the pads themselves were breaking up as well.