Spongy brakes

Tue Feb 11, 2014 2:06 pm

willnz wrote:As Brian says, the hissing is normal

If you think the servo diaphragm is damaged, start the car and then spray some "start ya bastard" or similar at the servo push rod behind the glove box. If the engine RPM increases, the servo is faulty.

What issues would a damaged servo diaphragm cause, mooshy brakes?

Tue Feb 11, 2014 2:22 pm

Yes, much heavier to operate brakes - you can test for this by coasting along in an empty car park and switching off the engine and pump the brakes a few times to empty the servo; the brakes then become very heavy to operate!

Also, you may find the engine running badly, due to excess leaking into the inlet manifold.

Tue Feb 11, 2014 2:27 pm

Brianmoooore wrote:
Fred555 wrote:
Used to have a can of can you buy it in London UK?
A can went for £20 on ebay last year, so I doubt if it's readily available! Bradex Easy Start is the UK equivalent.
Alternatively, use a propane blow torch with the jet removed. It's possible to get a car to start, run and drive (no petrol) with one of these directed into the air intake.

It's the apt title of "start ya bastard" that I used to enjoy - it always seemed appropriate at the kind of time it was being used. Bradex is very good but "start ya bastard" (probably the placebo effect of the name) always seemed just that bit more flammable.

Tue Feb 11, 2014 2:27 pm

Speedtouch wrote:Yes, much heavier to operate brakes - you can test for this by coasting along in an empty car park and switching off the engine and pump the brakes a few times to empty the servo; the brakes then become very heavy to operate!

Also, you may find the engine running badly, due to excess leaking into the inlet manifold.

As long as the car is running my brakes are easy to operate but when I pump my brakes when engine is cold and on idle it will run a bit rough every time I pump the brakes. The brake pedal is mooshy aswell. Currently waiting for a brake master cylinder for replacement.

Tue Feb 11, 2014 2:29 pm

Vacuum one way valve in pipe between servo and manifold?

Tue Feb 11, 2014 2:33 pm

Master cylinder seal rebuild kits are listed as on Real OEM check how much at the dealership or try ATE website

Tue Feb 11, 2014 2:39 pm

Fred555 wrote:Master cylinder seal rebuild kits are listed as on Real OEM check how much at the dealership or try ATE website

This is the hose you're talking about, right? How can I tell if the one way valve is functioning properly?

But the problem with mooshy brakes should not be cause because a leaking servo, should it?

Tue Feb 11, 2014 2:50 pm

I have a Mityvac alloy vacuum pump with gauge so I wold use that - but I guess if I didn't have one would try blowing through the valve and checking that it only passed air in one direction - bearing in mind that the vacuum suction is coming from the manifold end - there is probably an arrow on the valve too as it obviously has to be installed the right way round.

But it also looks like you are missing a hose clamp on that mid vacuum pipe elbow joint (or is that elbow joint meant to go straight into the servo itself? Looks like it would probably reach just fine - why is it there?) - so the vacuum could be leaking out even if the valve was OK - after all the valve is meant to keep the vacuum in the servo when the engine is switched off - you could try removing the crimped on clamps (often loosen with age) and fitting the right sized worm drive hose clamps instead.

Tue Feb 11, 2014 3:05 pm

But the problem with mooshy brakes should not be cause because a leaking servo, should it?

Well if there was low or no vacuum retained in the servo because of a:-

1.Leaky servo diaphragm OR

2.Bad hose and or bad / unclamped or otherwise not tight enough connections to the servo OR

3.Failing or failed one way vacuum valve OR

4. I think there is a big "O" ring between the servo and the master cylinder I think the vacuum could leak out via the "O" ring if it was perished

Then the brake pedal would feel different until the engine had built up the vacuum in the servo again.

As long as the car is running my brakes are easy to operate but when I pump my brakes when engine is cold and on idle it will run a bit rough every time I pump the brakes. The brake pedal is mooshy aswell. Currently waiting for a brake master cylinder for replacement.

Thu Feb 13, 2014 6:37 pm

Just a quick update. I replaced the master cylinder, and re-bled everything - the pedal is still long.

I will try bleeding manually rather than with the easi-bleed thing tomorrow/saturday, and if that doesn't sort it I will burn the car.

Thu Feb 13, 2014 9:18 pm

Altrezia wrote:Just a quick update. I replaced the master cylinder, and re-bled everything - the pedal is still long.

I will try bleeding manually rather than with the easi-bleed thing tomorrow/saturday, and if that doesn't sort it I will burn the car.

Haha, I also just changed my master cylinder. Any changes? No. Everything feels exactly as before.

When engine is off, pushing the pedal the first 10% is very easy and loose and doesn't affect brakes, the next 90% feels good and affects the brakes good.

When you start engine, the pedal is very loose on the first 50% but it starts affecting the brakes from 10-20%.

Maybe I should lengthen the push rod so that those 10% of no braking effects are going away. But I kinda like to have that 10% play so I can know for sure that the brakes are not braking constantly...

Also, I have sprayed start gas over all parts that are connected to the servo. No change in engine RPM whatsoever so I don't think I have any servo leakage.

By the way, what is the hose for that is going from the brake fluid reservoir somewhere into the bulkhead?

Tue Feb 25, 2014 10:57 pm

So; quick update to this.

I gave everything another check over, and most things looked good - drums, self-adjusters, no leaks etc - except the big vacuum pipe that goes from the inlet manifold to the servo - it was hissing and had a tear in it (but only when pushed by hand).

I replaced that, and re-bled the brakes but this time I used my wife instead of an easy-bleed kit, with the UP / YES I SAID UP / DOWN / NO NOT BACK UP YET!!! method.

Pedal is still a bit long, but it's no longer what I'd describe as spongy - just has a bit of travel before the braking starts.

I consider it a minor win.

- I'll try the bar adjustment at some point, but need to put some miles on the car - it may just be me being an idiot now.

Tue Feb 25, 2014 11:00 pm

Altrezia wrote:So; quick update to this.

I gave everything another check over, and most things looked good - drums, self-adjusters, no leaks etc - except the big vacuum pipe that goes from the inlet manifold to the servo - it was hissing and had a tear in it (but only when pushed by hand).

I replaced that, and re-bled the brakes but this time I used my wife instead of an easy-bleed kit, with the UP / YES I SAID UP / DOWN / NO NOT BACK UP YET!!! method.

Pedal is still a bit long, but it's no longer what I'd describe as spongy - just has a bit of travel before the braking starts.

I consider it a minor win. - I'll try the bar adjustment at some point, but need to put some miles on the car - it may just be me being an idiot now.

Good for you

I have the annual car inspection on the day after tomorrow so I will probably be back here crying very soon.

Tue Feb 25, 2014 11:13 pm

Altrezia wrote: this time I used my wife instead of an easy-bleed kit, with the UP / YES I SAID UP / DOWN / NO NOT BACK UP YET!!! method.

Been there and done that! Would probably have been divorced years ago if I hadn't invested in a pressure bleeder.

Thu Feb 27, 2014 1:14 am

Brianmoooore wrote:
Fred555 wrote:
Used to have a can of "start ya bastard" can you buy it in London UK?
A can went for £20 on ebay last year, so I doubt if it's readily available! Bradex Easy Start is the UK equivalent.
Alternatively, use a propane blow torch with the jet removed. It's possible to get a car to start, run and drive (no petrol) with one of these directed into the air intake.

My local GSF branch does Start Ya Bastard, along with a few other amusingly named sprays!

http://www.carplan.co.uk/index.cfm?category=93

Thu Feb 27, 2014 12:08 pm

gareth wrote:
Brianmoooore wrote:
Fred555 wrote:
Used to have a can of "start ya bastard" can you buy it in London UK?
A can went for £20 on ebay last year, so I doubt if it's readily available! Bradex Easy Start is the UK equivalent.
Alternatively, use a propane blow torch with the jet removed. It's possible to get a car to start, run and drive (no petrol) with one of these directed into the air intake.
My local GSF branch does Start Ya Bastard, along with a few other amusingly named sprays!
http://www.carplan.co.uk/index.cfm?category=93

Must get down to GSF and lay hands on a can - this is just one of the reasons why internet parts buying just can't replace a physical trip down to the local Motor Factors.

Coincidentally already have a can of "BELT UP" - pretty good stuff.

Brianmoooore means that the propane torch is what will run & drive a car without petrol NOT the Bradex.