mcfly94 169 Posted June 27, 2013 Hey guys for some reason when I pump my brakes my idle raises its XF with 250. And how do you know if your booster is gone, my breaks squeal, creak and are sponging. Share this post Link to post Share on other sites
ILIED 316 Posted June 27, 2013 Change the fluid and see if they're still spongey.My tip is to use a different colour to the fluid thats already in there. If its yellow in there, pick a blue one, so you know when you've got all the old fliud out.As far as the idle, I'm thinking the NRV isn't working correct. Share this post Link to post Share on other sites
SLO247 1,713 Posted June 27, 2013 Non return valve? The one that goes into the booster. Share this post Link to post Share on other sites
revhead 1,392 Posted June 27, 2013 generally id say change the nrv if it doesnt stop the prob change the booster when depressing brake pedal listen to the booster for hissing noises etc Share this post Link to post Share on other sites
mcfly94 169 Posted June 27, 2013 generally id say change the nrv if it doesnt stop the prob change the booster when depressing brake pedal listen to the booster for hissing noises etc I can sort of hear noises coming from that area/ hard to change non return valve? Share this post Link to post Share on other sites
revhead 1,392 Posted June 27, 2013 well id say the diaphragm in the booster is shot ,have you got another booster kicking around ,pretty easy job ,just undo master cylinder pull it forward un bolt booster ,should take 30 mins tops Share this post Link to post Share on other sites
mcfly94 169 Posted June 27, 2013 may have to grab another booster and give that ago!, cheers guys! Share this post Link to post Share on other sites
revhead 1,392 Posted June 27, 2013 3x bolts under dash 9/16 clip on brake pedal, 2x 9/16 bolts from master to booster that is all for the love of ford dont undo your brake lines ,not needed just pull it out of the way Share this post Link to post Share on other sites
gerg 10,871 Posted June 27, 2013 whats the nrv? Non-return valve I guess. Spongy brakes could be a lot of things. Pads can delaminate and become a bit bouncy over time, fluid can get air/steam pockets in it, brake hoses can bulge under pressure, loose wheel bearings can cause pad/caliper knockoff, the list goes on. Your idle rpm increases because your booster consumes vacuum from the engine, so it's the same thing as a vacuum leak. It should, if at all, increase only for a second. If it continues with your foot on the brake, your booster is faulty. 1 revhead reacted to this Share this post Link to post Share on other sites
mcfly94 169 Posted June 27, 2013 Found a spare nrv in the garage so ill give that ago. My front brake hoses are cracking etc.. have new one to replace, so they could be bulging. Don't think I have loose wheels bearings. Pads could need changing, do need new rotors. Share this post Link to post Share on other sites
Lord_fahrquhar 2,580 Posted June 27, 2013 In the booster there is a ceramic disc which the pushrod passes through to the booster. If you hear a hiss its likely cracked and leaking air past the booster. Only happens if you put a bit of force on it. = increased air to engine higher idle. Share this post Link to post Share on other sites
mcfly94 169 Posted June 27, 2013 god damn brakes, hopefully get to the bottom of this soon, what are the chances of master cylinder gone? Share this post Link to post Share on other sites
revhead 1,392 Posted June 27, 2013 if you pull it forward look at the back to see if its leaking fluid,other wise no its the booster Share this post Link to post Share on other sites
mcfly94 169 Posted June 27, 2013 if you pull it forward look at the back to see if its leaking fluid,other wise no its the booster forward out of the booster? Share this post Link to post Share on other sites
revhead 1,392 Posted June 27, 2013 forward out of the booster? correct towards the front of the car. Share this post Link to post Share on other sites
mcfly94 169 Posted June 27, 2013 correct towards the front of the car. alright thanks mate, will get another booster and check everything out, cross fingers! Share this post Link to post Share on other sites
revhead 1,392 Posted June 27, 2013 youl be ok ,youl notice the rear of the master cylinder is clean its ok but if it looks a bit sugary white n crusty at the rear its shot or if its just plain pissing out fluid, 1 mcfly94 reacted to this Share this post Link to post Share on other sites
mcfly94 169 Posted June 28, 2013 Slightly improved by changing nrv. Will grabbing another booster to see if can improve it anymore, but no noises atm. I think my spongy breaks are definitely down to flexing brake lines and fluid. Share this post Link to post Share on other sites
Crazy2287 1,888 Posted June 28, 2013 Change fluid before you worry about brake lines. Standard lines will still give pretty good pedal feel. But the tiniest bit of air in the system will send it up the duff. Share this post Link to post Share on other sites
mcfly94 169 Posted June 28, 2013 Change fluid before you worry about brake lines. Standard lines will still give pretty good pedal feel. But the tiniest bit of air in the system will send it up the duff. My front standard lines are cracking and brittle, and I already have the new ones in the shed , I used bendix dot 4 before, is that alright? Share this post Link to post Share on other sites
Crazy2287 1,888 Posted June 28, 2013 I'm not sure. All dot 3's are compatible. I think some dot 4's are not. Look into that one mate. I'm using nulon super dot 3 but all those standard brake fluids are just brake fluids. Do not mix types. Thes the only thing with brake fluid really. Until you start getting into the exxy high temp stuff for hectic race applications. Sure, if you already got the lines fit em! Share this post Link to post Share on other sites
mcfly94 169 Posted June 28, 2013 Will do, wont wont hurt to run all new fluid through when I do the lines, and reseal the front calipers Share this post Link to post Share on other sites
ZL. 19 Posted June 28, 2013 When i got my calipers reco'd the bloke told me to flush the brake lines with methylated spirit to get all the water out, but let it dry and evaporate off before you put in your new fluid, also as said dot 3 dont mix with dot 4. and silicon brakefluid is a waste of time( dot 5 ). Share this post Link to post Share on other sites
ZL. 19 Posted June 28, 2013 because brake fluid is hygroscopic it absorbs water from the atmosphere, thats why its good to flush with metho. Share this post Link to post Share on other sites