Clutch & Brake Pedal heavy on first push?

[GrahamC230K]

Just wondered if the following is an obvious sign of anything that might require a closer look (car goes in to garage in a week anyway).

I have noticed that recently, when the car has been left overnight, the first time I depress the clutch and come to think of it the brake pedal, they are really heavy. After the first press they are back to normal.

Also from time to time (not on 1st start, when driving) I can't get 1st gear, I have to release the clutch then depress again, then all back to normal too.

Is this typical of anything?

 

[Brian WH]

Just wondered if the following is an obvious sign of anything that might require a closer look (car goes in to garage in a week anyway).

I have noticed that recently, when the car has been left overnight, the first time I depress the clutch and come to think of it the brake pedal, they are really heavy. After the first press they are back to normal.

Also from time to time (not on 1st start, when driving) I can't get 1st gear, I have to release the clutch then depress again, then all back to normal too.

Is this typical of anything?

Fluid may be ready for a change, every two years normally.

 

[jimmy]

Fluid has been changed so wont be that.

It is because the brakes and clutch are servo assisted, this is operated via a vacuum from the engine. Obviously when you first start the car you have to wait for the vacuum to build up pressure erm vacuum I mean. Cant say as I have noticed it on mine, brakes are fail safe dual circuit sytstems so you it is not possible to lose all braking, just some!! Unless you have a new electric controlled braking circuit and who knows if they are fail safe?

The only thing I can think of is that your servo has developed a leak, can you hear a hissing or sucking from around the servo unit?

 

[Brian WH]

The only thing I can think of is that your servo has developed a leak, can you hear a hissing or sucking from around the servo unit?

Surely if the servo was leaking the brakes would be softer, not harder.

 

[jimmy]

Surely if the servo was leaking the brakes would be softer, not harder.

If there was no servo assistance the pedal(s) would require more effort......I think If there was a fluid leak the pedal would be easier/softer, it should be fairly easy to check for a fluid leak, keep an eye on the reservoir.

 

[GrahamC230K]

The only thing I can think of is that your servo has developed a leak, can you hear a hissing or sucking from around the servo unit?

Where's that then?

 

[Simon]

Where's that then?

Big round black thing near the fuse box.

 

[GrahamC230K]

OK, thanks guys.

Is the brake fluid seperate from the clutch fluid or is it the same pool?

I am guessing shared as Jimmy says it has been changed and we (I watched OK!) changed what I thought was the brake fluid.

The fluid level is fine.

There is no hissing or sucking sound from the servo, but engine running, bonnet up, pumping the brake pedal makes a sort of fumfing sound from the servo. In my unqualified opinion this seems normal?

It's the stiff first push of the clutch that strikes me as odd, I can totally live with it just didn't want to ignore a potential sign of a greater problem.

 

[Ian B Walker]

IMHO the sound from the servo sounds like an air leak and you say that the fluids been changed. Manual clutches on Mercs are a swine to bleed. Usually ending up with connecting a brake cylinder to the clutch slave cylinder and bleed through the foot brake. Sounds confusing, anyone interested and I will write up a how to.

 

[GrahamC230K]

The brake fluid has been changed. If this is the same as the clutch fluid, fair enough, otherwise the clutch fluid if seperate hasn't been changed.

Any other opinions on my fumfing sound? - Remember only quiet and only when pressing brake pedal.


Does any of this have any bearing on the most inconvenient issue of sometimes not being able to get 1st gear without releasing then depressing the clutch again?

 

[Brian WH]

Does any of this have any bearing on the most inconvenient issue of sometimes not being able to get 1st gear without releasing then depressing the clutch again?

Are you having other clutch problems Graham.

Extract from another thread-

"For when I need to replace mine, I also wonder what the chances are of finding a more substantial replacement. Mine does not slip in normal conditions, but does seem to overheat and once hot, it does slip momentarilly from time to time".
__________________

All this indicates to me that you have a problem with the operation of the clutch. ie release is not efficient.

Could be air in the clutch fluid system,fluid needs changing/bleeding or worn clutch plates.

As it is going into the garage discuss with them and let us know.

 

[GrahamC230K]

The slipping only really occurs when abused, but I guess it could all be related. I will for sure have it checked out on Friday.

Car stops and have enough grunt to pull away in 2nd, worst comes to worst until then!

 

[GrahamC230K]

OK, the "fumf"ing sound I spoke of can actually be heard in the car whenever the brakes are pumped (at a standstill, engine running) - this is normal or not?


I shall bring up the issue of occassionally not being abke to get 1st gear at the Service next week, but I don't want to waste labour time, diagnosing faults that are not faults.

 

[teky]

the "fumf"ing sound is the vacuum pressure builing up but it should not be there, possible air leak from servo inside car at the point where it goes into the engine bay "you might hear a small hiss of leaking from the peddle area" you can rebuild the system they do kits for that but its a sod of a job, other things to check are the one way valve in the vacuum line and the line its self from the booster

just put a d up there where it says builing before some person makes a comment about my spelling

 

[Brian WH]

OK, the "fumf"ing sound I spoke of can actually be heard in the car whenever the brakes are pumped (at a standstill, engine running) - this is normal or not?

It does not appear to be affecting the brake efficiency at the moment so perhaps one to keep an eye on. If you find that the brakes need more than the usual effort and you have to press further than you did for the same braking effect, then is the time to worry and have someone check the servo for leaks etc.

 

[Ian B Walker]

just put a d up there where it says builing before some person makes a comment about my spelling

A p**** Sir I am not and take offence at your comment. An apology would be accepted.

 

[GrahamC230K]

Easy, the topic is my dodgy clutch, I don't see how any offence could be taken at the comment, but also it must have taken much longer to write than to correct the typo!

 

[teky]

my feeling as well loss of vacumme