Strange Noise / Vibration maybe brake system

nerox · Post by **nerox** » Tue Mar 01, 2011 2:21 am

i've noticed a strange noise coming from the engine

a few weeks ago it sounded like a high pitch squeak which lasted about 3-5 seconds but in the past few days its changed to a much louder rumbling noise and at the same time i get a vibrating in the pedals (it seems worse in the brake pedal). then after a few seconds it goes away.

it mostly seems to happen when parked up with engine on but i've also noticed it once while driving.

It lasts about 5 seconds. seems to occur about every half hour but thats just a guess.

i've tried revving the engine, moving the steering wheel and pressing the pedals while its happening but neither do anything to change it.

any ideas ?

inthemaking · Post by **inthemaking** » Thu Mar 03, 2011 10:15 am

So it does it while idle mostly?

darthroush · Post by **darthroush** » Thu Mar 03, 2011 12:16 pm

If the noise is coming from the engine while you are stopped, how could it be the brakes?

inthemaking · Post by **inthemaking** » Thu Mar 03, 2011 12:29 pm

sidepipe87 · Post by **sidepipe87** » Thu Mar 03, 2011 12:46 pm

bad bearings in a pulley? fan kicking on?

Post by **occasional demons** » Thu Mar 03, 2011 12:56 pm

sidepipe87 wrote: fan kicking on?

Bam. Check for a missing fan blade.

IIRC, there was some issue with the blades breaking?

nerox · Post by **nerox** » Thu Mar 03, 2011 1:12 pm

yes it does seem to do it mostly when stopped but it has happened a couple of times when driving.

the only reason i thought it could be the brakes is the vibration through the brake pedal at the same time as the noise.

i dont think its the fan as it dosen't correspond to the fan coming on / going off.

i guess as i've had the car over 2 years it would be a good idea to change the brake fluid, see if it helps ?

Post by **occasional demons** » Thu Mar 03, 2011 2:28 pm

Brake fluid won't cause the vibration.

If it stays constant whether you rev the engine or not, it lessens the likelyhood of an engine driven part, but it is still possible I guess.

Could be a tensioner pulley or a bearing/bushing in the transaxle/clutch. It has to be something that is shaking bad enough to feel it in the pedals. IDK if a tensioner pulley is capable of that kind of vibration. A missing fan blade, I could have seen, but if the fan runs, and there isn't any feedback from that, well it shoots that down.

You may just have to start it, open the hood, pull up a chair and wait. Then try to pinpoint where it is.

nerox · Post by **nerox** » Sat Mar 05, 2011 1:41 pm

Ok so i have check the fan and its perfect, no broken blades, no damage at all.

I left the engine to run for about 30 minutes while i was doing the crimp terminals for the lights and didnt hear the noise at all

the only reason that i suspected the brakes (maybe not pads and discs) more like the master cylinder or something, is that i recently had problem with the clutch and it turned out it nedded hydraulic fluid change and that cured the problem. So if the brake and clutch fluid were the same age they could both need replacing and hence bad fluid causing problem (although i'm likely talking crap)

I've taken some pictures of the fluid to see if anyone can tell if it looks bad or normal

Brake fluid in resevoir

I took some out in a syringe

A drop of the fluid in my car (left) next to a drop of brand new fluid

Danteneon · Post by **Danteneon** » Sat Mar 05, 2011 3:20 pm

That fluid should be changed, but I can't see it causing the noise you are talking about

Post by **occasional demons** » Sat Mar 05, 2011 4:07 pm

Yeah, that's pretty normal looking fluid for it's age.

nerox · Post by **nerox** » Sun Jun 26, 2011 1:31 pm

UPDATE :

i was parked up at work the other day with the engine running and i had my foot on the brake pedal because i cba to put the handbrake on.

the car made the same noise as usual and at exactly the same time the brake pedal went soft and dipped about 1/2"

it felt like when you pump the brake pedal with engine off so its stiff and then start the engine, the pedal moves down a bit.

any help ?

OB · Post by OB » Sun Jun 26, 2011 3:24 pm

Perhaps you have a vacuum leak, possibly in the brake booster. This would explain the vibration (due to idle change) as well as the pedal feeling a bit weird. Do you have the AC on when this happens by chance?

nerox · Post by **nerox** » Sun Jun 26, 2011 4:58 pm

it happens all the time, wether the AC be on or off.

what would be the remedy of this vacuum leak ?

steamer1227 · Post by **steamer1227** » Sun Jun 26, 2011 5:14 pm

Pinpoint where the vacuum leak is n replace hose or if the booster is leaking replace that. Maybe the bladder inside went bad but then I think u would lose break pressure alot more.

OB · Post by OB » Sun Jun 26, 2011 5:26 pm

In theory, if the booster had a leak, the pedal would feel stiffer proportional to the size of the leak. However, it's possible that the booster has failed in another way, which may cause unusual pedal feel. Tell me this, when the pedal acts up, does the idle seem affected? Does it sink after the engagement point (when the brakes actually grab during pedal compression)?

Being an R/T, the car should have ABS. This would be my next guess. It's possible that the ABS system is acting up, which can cause unusual pedal behavior and vibration. I doubt it is a wheel speed sensor, since it does it when not moving. Possible HCU (hydraulic control unit).

It would be easier to narrow it down with a much more detailed description of the symptoms.

nerox · Post by **nerox** » Sun Jun 26, 2011 5:26 pm

I havent really noticed much loss in braking. I've got EBC redstuff pads on and compared to my old car which had the same setup, the brakes are nowhere near as good ... i know that dosen't necessarily mean much but could be a sign...

how exactly would i find out where the leak is ?

OB · Post by OB » Sun Jun 26, 2011 5:32 pm

Some people will spray brake cleaner, carb cleaner, or anything that can double as fuel, to spray around the suspect areas. If the leaking area ingests the auxillary fuel, engine idle will increase, since there is now an unmetered air fuel mixture being added beyond the throttle body. A bad leak will make an audible hissing noise. A good visual inspection of the vacuum lines is a good start.

nerox · Post by **nerox** » Sun Jun 26, 2011 6:36 pm

OB wrote:In theory, if the booster had a leak, the pedal would feel stiffer proportional to the size of the leak. However, it's possible that the booster has failed in another way, which may cause unusual pedal feel. Tell me this, when the pedal acts up, does the idle seem affected? Does it sink after the engagement point (when the brakes actually grab during pedal compression)?

Being an R/T, the car should have ABS. This would be my next guess. It's possible that the ABS system is acting up, which can cause unusual pedal behavior and vibration. I doubt it is a wheel speed sensor, since it does it when not moving. Possible HCU (hydraulic control unit).

It would be easier to narrow it down with a much more detailed description of the symptoms.

a-ha now you see it is starting to make sense!

yes there is a change in idle speed at the time of the noise.

from what i can tell during the couple seconds that it happens ... the revs seem to rise just a tiny bit about 0.5 second before. Then there is also one clunking noise (like when you turn the AC on, you can hear the compressor engaging) and then about 0.5 seconds after i get the noise and the vibration in the pedal. the noise and pedal vibration can last 1-5 seconds and then it goes back to normal.

also the other week it was a bit different one day and instead of this happening once and being done with. there was a series of mini-events where the revs rose, got the clunk, and then just a tiny little squeak. this happened again every 10-20 seconds for about 2 minutes until i turned the engine off in fear of ruining something

OB · Post by OB » Sun Jun 26, 2011 6:40 pm

Can you try to describe the noise in more detail? Try to listen to it without taking into account any vibration or feeling in the pedal. What does it sound like if you stand outside the car? Standing in front of the engine?

Donkeypuncher · Post by **Donkeypuncher** » Mon Jun 27, 2011 1:01 am

Wasn't there a recall on the brake booster hose?

nerox · Post by **nerox** » Mon Jun 27, 2011 1:07 am

The noise is quite tricky to describe ... its a click then a deep rumble (sort of like the vibrate on a phone but MUCH louder)

i'll see if i can get a sound clip

steamer1227 · Post by **steamer1227** » Wed Jun 29, 2011 10:35 pm

Could it possibly be within the abs unit as stated before. Maybe the unit is trying to apply the abs. ?

nerox · Post by **nerox** » Thu Dec 01, 2011 5:40 pm

Update:

I was sat in the car park at work with the engine running and the noise started again, so i opened the hood and at the time that the noise / vibration occus, it seems the brake booster is doing something internally coz it shakes like mad...

time for a new one?

nerox · Post by **nerox** » Sat Jan 21, 2012 1:08 am

bump for some help ?

Post by **occasional demons** » Sat Feb 04, 2012 5:33 am

It has to be either the booster, or the ABS unit. Tho I am not sure the booster alone would affect the ABS unit, unless it was pushing the master cylinder when it was doing whatever it is doing.

The vibrating may be coming from the ABS unit, unless it is the diaphragm in the booster actually flapping as vacuum escapes by it. Kind of like a balloon when air escapes.

I believe a booster is cheaper than an ABS unit. That is where I would start, if something is to be replaced. It is about a 4 hour project, if you have not done it before. The FSM recommends a new brake light switch, as removing the original supposedly does something to it, where it cannot be readjusted.

INVUJerry · Post by **INVUJerry** » Sat Feb 04, 2012 8:19 am

I'd assume the abs system because if the sound he's describing. Sounds like when I slam the brakes and the abs engages.

If you want to get away cheap see if a local shop (or yourself) would bypass the abs unit temporarily to see if that fixes the issue.

nerox · Post by **nerox** » Sat Feb 04, 2012 9:02 am

occasional demons wrote:unless it is the diaphragm in the booster actually flapping as vacuum escapes by it. Kind of like a balloon when air escapes.

that is pretty much what it sounds like!

occasional demons wrote: The FSM recommends a new brake light switch, as removing the original supposedly does something to it, where it cannot be readjusted.

thanks for the heads-up on that, id never have known! i just looked at one and it says 'do not reinstall' on the back

Ive ordered a refurb booster and a master cylinder (it was only $30) so hopefully that'll clear the problem

maurymw · Post by **maurymw** » Wed Feb 22, 2012 10:28 pm

nerox · Post by **nerox** » Sun May 13, 2012 8:04 am

Fitted New

- Booster
- Master Cylinder
- Front Calipers
- Front Caliper Hoses

Flushed all through with new DOT4 fluid and problem still exists

2GN.ORG

Strange Noise / Vibration maybe brake system

Strange Noise / Vibration maybe brake system

Coaxial Adapter