Grinding noise between 1000 and 1500 rpm

[Colley 0]

Hi guys,

 

Hopefully someone can suggest something...

 

Since the cold has really kicked in i've noticed that when i'm slowing down and the revs drop down to between 1000 and 1500 rpm there is a kind of grinding sound? It doesnt happen when accelerating and it doesnt occur when you put it in neutral. Any suggestions would be apprecaited so i can investigate further. I expect the problem to be expensive seeing as i have jsut paid out for suspension and thats the way things usually go! :(

 

Cheers

[Kevin Bacon 5]

I suppose mechanically speaking, it has to be braking or gearbox related if it's not doing it in neutral or when accelerating....assuming it's not the chains, as they make a nasty noise at 1200rpm when goosed.

 

I know that when the pedal position sensor in the brake servo is shot, the ECU doesn't know where the pedal is and activates the pump at those sort of rpms. Do you feel anything through the pedal?

 

Noises/vibrations are very difficult to diagnose without seeing the car.....so this thread could contain many shots in the dark before we find the cause!

[dr_mat 0]

Good point- you say it doesn't happen when accelerating or when in neutral, but does it also only happen when you're braking?

I had graunchy noises at low speeds due to iffy ABS sensors on an old Cavalier once. The ABS was kicking in for no apparent reason.

[Colley 0]

Cheers chaps, would VAG-COM be able to shine some light on the problem maybe?

 

I have a feeling it maybe gearbox related, but thought maybe someone might have had a similar experience.

 

The car doesnt feel any different to drive its just a worrying sound, i'll get it checked out but wanted a few opinions before hand.

[Kevin Bacon 5]

VAG-COM will tell you if it's ABS related (including the PPS) but mechanical grinding is sadly missing from it's list of checks ;-)

 

OK, so if we look at the box then, the grinding is occurring on the overrun obviously.... Inner CVs only making noises under load (clicking usually), so it won't be them. Diff's and layshaft bearings whine/rattle on overrun when knackered, but not a 'grind', so that's ticked off the list too.

 

Can this grinding be felt through the pedals and column at all?

 

Some VRs make a "grrraaaunch" when pulling away in 1st, but I've never heard in on the over-run.....

 

Dunno mate.....if you're near Warwickshire, drop it into Stealth is my advice!

[silverado2l16 0]

ive got a 2L 16v corrado with a tinny/rattle sort of noise at approx 39000 revs in every gear and neutral..the noise appears then goes, it pulls fine after the noise??? :? dont think its the exhaust ??help!!

[Supercharged 2]

silverado2l16, Welcome to the forum!

 

Check the heatsheild on the CAT - may just have gone at one of the spot welds which is hard to spot without getting under there and someone else reving the engine...

[Trig 0]

Yeh sounds likely, I had the same problem. You get a reverberating at a specific rev range, easily fixed as well :)

[silverado2l16 0]

nice one ill check it out !!cheers!!

[silverado2l16 0]

ive got the non active spoiler problem as well, i can pull the spoiler up and down by grabbing it !!but it doesent move at speed and doesent move with the switch ??

[Supercharged 2]

Checked yer fuses?

[silverado2l16 0]

the 15A in slot 16 was gone, which does the warning lamps i think.but ive changed it still no glory !!

[Supercharged 2]

Check it again to see if its gone - it might be the one, they moved the spoiler about a bit...

[silverado2l16 0]

just done that in the cold rainy weather, fuse is still intact! prob the motor itself how much do they cost do you reckon ?

[Supercharged 2]

Not sure mate - I'd check power up to it before spending any wonga...

[silverado2l16 0]

yeah definately..do i just take the plastic off the underside of the boot and test with a meter?

[Supercharged 2]

Yeah - while pressing the switch...

 

If you don't I've got a spare control unit I can send over for you to test (It's mounted close the the switch)

[chubbybrown 0]

Silverado,it could be the thrust relase bearing on the clutch,

esp if your pulling away or in neutral

[silverado2l16 0]

yet to test power to the spoiler will try to get it sorted soon, sort of ruins the character of the rado when its not workin! aswell as the mystery noise at 4000 revs the clutch does stick in sometimes so maybe your right Chubbybrown??

[silverado2l16 0]

the spoiler mystery continues!! the switch is working and the moter is working(makes a noise when pressing the switch)??but it still wont go up and down with the switch or at speed ??

[Supercharged 2]

Is the mechanism free - can you wind it manually?

[silverado2l16 0]

all sorted!!yay!! turning it manualy when it became stuck, thought id broke it!!tryed it with the switch and it worked...must have been out of sync??the tinny noise was the cat heatshield so thats cool......the only problen ive got now is somtimes the clutch sticks in ?? how much is a new clutch do you think and are they easy to fit?.....cheers for your advise!!

[Supercharged 2]

Good good, the spoiler motor has a thermoswitch cut off and the control box stops trying after 12 seconds so it may have been jammed and you've just freed it...

[silverado2l16 0]

well chuffed !!!!glad its sorted!!

[dr_mat 0]

The automatic spoiler action can be detached from the motor by using the manual wind. If you could lift and lower the spoiler from outside the car BY HAND it wasn't engaged to the motors - no way you'd be able to do that otherwise.