Slowing but not stopping

So I used the bus about 2 weeks ago and all was fine.
Due to the weather he has been sat on the driveway since then (covered) until we had a nice day at the weekend and I decided to take him out for a nice long drive.

Normally the brake pedal is quite high and even when jumping on it it doesn't go right to the floor, so off we go and as I try and stop at the end of our street the bus doesn't seem to be stopping, it was slowing down and did come to a rolling stop however in my panic I tried standing on the brake harder than usual and the pedal went virtually right to the floor (with a small amount of resistance but not as much as usual)
I thought it might be just me as I hadn't driven it for a couple of weeks and thought I had just got used to my other car so I carried on driving and it soon became apparent that it wasn't just me, the bus is stopping but regardless of how hard I press the pedal it still only slows it before coming to a rolling stop, so I turned around and came home. (I know it's bad but I was more concerned about not stopping and damaging the camper than I was about running anyone over! :-[ )

Any ideas on what this could be? There is plenty of brake fluid and the brakes were checked and bled less than 3 months ago?

It might be time for me to phone dadcover.com ;D

 

Might be the servo if it has one. Or just an airlock

 

If the brakes were bled properly (are you sure?) you might have a failing master cylinder. If the servo had failed the brake would not go to the floor, just feal hard and ineffective (try your brakes before you start the engine to experience no servo)

If the brakes were bled by pumping the brake pedal that can cause an old seal in the master cylinder to finally give up by makinig it travel to a less worn part of the cylinger, usually over a ridge.

Did you try pumping the brakes as you stopped? If they firm up on pumpng I would suspect water or air in the brake fluid, but if bleeding them does not solve it then its the master cylinder.

 

And just in case you do have a servo problem its worth checking that the servo vacuum pipe is still attached to the (or one of the) carbs?

 

Did you adjust the rear brakes? If you pump and it firms up try doing that first.
If it does firm up and you have a servo, test the servo: Engine off, pump pedal to firm up with you left foot, Keep pressure on pedal while starting engine and the pedal should sink an inch or so. If it does, the servo is working. If servo not the brakes should still work as normal but you have to press harder.
If no amount of pumping gives a firm pedal, you have air in the system, M/C problems as suggeted by DD above, or a big leak.

 

Thanks, Ill give all the above ago when the weather cheers up

 

That'll be May then?

 

??? ;D

 

Really does sound like air in the system. If you can get hold of a gunsons easybleed and use it to force the flid through. make sure you drop the pressure in the tyre to 20psi max or you can damage the seals in the system or the easybleed will blow fluid everywhere.

also make sure you dont have even the tiniest bit of leakage at the bleed nipples once tightened up.

 

I agree with earlylatebay to the letter ^, plus don't use the supplied in line bottle to top up the reservoir or again, fluid will go everywhere...

 

Its just as easy to couple up the empty bottle to press up the system as long as the reservoir isn't allowed to empty.

 

I've had the same symptoms with my bus, and it was the master cylinder with an internal leak.
Tony

 

Just a word on EasyBleed. I have had and used one for about 12 years on several old motors and now on my bus. It did a great job a couple of weeks ago and my bus sailed through its MOT.

I have never had a problem using mine and the secret, as Earlylatebay said, is to set the spare at 20psi. You should double check that you have the correct cap for your fluid reservoir, and that the connections are pressure tight and the seal is the right size. The supplied bottle has always worked for me, but you must remember to remove the connection from the spare to let the pressure out, when you need to top it up.

Do NOT try to let out the pressure by unsrewing the cap from the bottle as that will get fluid everywhere and empty your tyre!.

Always wait 10-15 minutes after topping up for any air to come to the top and carefully reconnect and repressurise. Check in advance that you have a drain tube that fits each nipple remembering that the front caliper ones may be a different size from the rears. Open the nipple and watch the fluid flow. Nice and easy.

After pressurising, the first thing to do is to check that there is no fluid leaking from the flexible pipe between the upper and lower reservoirs, or indeed anywhere else or you have work to do before you can bleed the brakes. This is the only way to check that connection pipe and a good time to do it. Other leaks are tested by the master cylinder and should be obvious.

Slow and steady wins the race in this case and last time I did a complete fluid change it took 30 minutes.

 

Thanks for the advice, I will look into the easybleed.

We ended up replacing the master cylinder and the brakes were then ok, drove it a few times and all was fine. However due to rubbish weather we have had recently the van has spent a few weeks tucked up under a cover on the driveway, went to go for a drive on new years day and the brakes had gone again even though they were fine when I parked up? Brake fluid again is fine, no leaks (That we can find) Bleed the back brakes and this had no effect, bleed the front brakes and the pedal then came back up.

Not sure if the new cylinder is faulty or not?

 

There may be a slow leak in the system so after bleeding is ok then overtime deteriorates. Check your flexi hoses are not leaking and no leakage from any join.

Hope you get it fixed