I've got a very annoying creaking noise coming from my brake pedal when depressing it. The harder it is depressed, the louder the creaking noise is. I've searched the forums to no avail.

Today, I took the brake pedal linkage apart, greased the bushings. I then removed the master cylinder from the power booster. Moved the power booster to my workbench and inspected all thoroughly. It must be an internal noise coming from the booster. I put some lithium grease on the rod and greased the felt seals that go around the rod. Reinstalled all but the noise continues.

Got frustrated, took it all apart again, this time sprayed some Kroil up inside the booster. Moved on to the master cylinder. Pushed the piston up in the master cylinder slightly, sprayed Kroil up in that. Nothing remains that hasn't been lubricated. Creaking remains.

Any recommendations or anyone that has had a similar problem? A reman. booster costs about $110-150. Am 90% sure it is coming from the booster but there is a slight chance it could be coming from the master cylinder. Thoughts?

 

Mine has done it since new, as have a couple other F-150's I have been in. Hate to say it, but I think its just the nature of the beast

 

My 07 has done it since i got it 6 months ago. They put a booster in it last week and it sounds exactly the same. They say its normal so until i can compare it to another new truck i guess i gotta live with it.

 

I have this same problem. I did everything you did too.. several times. Still have it. So, you aren't alone brother.

 

don't have the creak, but I have a clunk. it appears randomly and I'm 99% sure it's the pedal itself.

sounds like you've done everything possible. try turning the radio up?

 

Maybe the noise is coming from the Brake pedal position swith? Just a thought.

 

STOP DRIVING YOUR TRUCK

Kroil is a mineral oil.
https://secure.cnchost.com/kanolabs....oil_liquid.pdf
(at least I'm 95% sure its mineral oil based on the above link to the MSDS sheet)

Mineral oil DESTROYS the master cylinder and booster. It is only a matter of time till your seals fail. Potentially all the seals will fail depending on how much oil you sprayed into the master cylinder.

This is for real - I design and test master cylinders. The seals are made of EPDM rubber since EPDM stands up to brake fluid. But when exposed to mineral oil the EPDM swells up and gets soft. The booster diaphragms are EPDM and so are all the seals in the MC. Its a crapshoot to see which fails first.

You need to get a new booster and master cylinder.
Do NOT drive your truck till you replace them. You also need to thouroughly flush the entire brake system and then hope you didn't get enough oil exposure to trash your ABS or wheel calipers.

Again, this is not a joke. I am a master cylinder engineer. This is very serious and you could have a full brake system failure - there are 2 circuits but if you trash both sets of seals by spraying Kroil into the MC you loose all braking.

 

I have no knowledge about brake components, but I do now that any type of mineral oil WILL destroy EPDM in a very short period of time(yeah ask me how I know...my RV's roof is made out of the stuff, and now has many patches on it). So if the MC seals are in-fact made out of EPDM, then I'd be very inclined to follow his advise.

 

Good call mkosu04. Surprisingly that never occurred to me. But you are correct. I have seen this many times over the years, mostly people filling the master cylinder or topping off with the wrong fluid. Once a fella dumped about a half quart of transmission fluid in the master cylinder to fill it up due to a leak in an older vehicle, Then a short time later, we had to replace master cylinder, flush the whole system and replace front calipers, both rear slave cylinder and find the leak. You should have seen the seals swelled and were completely worthless. This is indeed serious. And todays technology, allot more can happen and get expensive quick. Don't want to freak you out rcknybn, but I don't know how much of this you sprayed in and even if it will cause a problem down the road. But I belive if any of the spray got into the wrong place I wouldn't drive it untill I have read the contents of Kirol, Replace master cylinder and booster and flush the brake system. I'd have to check the manual with procedurs on flushing out the ABS system. Keep your fingers crossed. Hope all works out for you. And while your doing that, check out that cheap plastic BPPS.

 

That's got to irritate him. All that work, never got rid of the squeak and now he's got to spend more money and do more work for a problem that was never going to go away no matter what he did.

Should have just turned up the radio.

 

I got the same kind of noise coming from my brakes when im getting off them. Really hopping this recall on the brake line or whatever for the 05 and 06's fixes it though. If i ever take the time to go to ford

 

Guys - thanks for the input. Looks like I screwed the pooch on this one.

I was so impressed with the Kroil in removing the spark plugs, I guess I thought it would work on anything. Didn't even remotely consider the consequences of putting it on a rubber surface.

I'll get the booster replaced this evening. Since I merely sprayed it in the piston area of the master cylinder, does anyone know if a piston kit is available. Or does the whole cylinder have to be replaced?

Thanks and keep that positive criticism coming (unless my ex-wife is reading this).

PS - Matt - I need to clarify that I didn't spray the Kroil directly into the master cylinder reservoir, just around the piston on the back side that meets the booster. Still need to flush the brake system?

 

REally sorry to hear about your trouble now having to replace everything. When it rains it pours huh
I guess I have just learned to tune the noise out, kinda sad a 30k truck squeeks but I figure if thats the biggest complaint I have im doing good

 

Sorry for the absence... I was on vacation

You can't get any kits to replace the insides of a master cylinder... the only serviceable parts are the reservoir, reservoir cap, and possibly the Fluid Level Indicator switch.

It sounds like you're brake system should be ok, but I would replace the master cylinder and the booster if it were my truck. Why take the chance of crashing due to a MC failure? Then flush the system good to remove any traces of Kroil and you should be ok hopefully.

Good luck!

And don't feel too bad... if I were not a MC engineer I never would have guessed that this would be an issue and may have oiled mine if it were squeaking.

FYI to anyone who may find this with a search in the future - if your master cylinder does squeak... change the brake fluid, don't oil it. New brake fluid (with fresh additives) should remove any squeaks.

 

Its hard to diagnose the noise without being there... I've never noticed any squeaks in my brake pedal.

What you can do is spray the pedal linkages with some silicon spray. Just don't spray anything into the back of the booster (where the rod goes through the dash panel... AKA firewall)

If the noise is in the pedal linkage this should hopefully fix it for awhile.