weird noise while in reverse

chevaps · 10-02-2009, 10:51 AM

The other day i noticed a weird noise coming from under my bonnet while reversing. I can get the car into reverse fine, but as soon as i start to reverse, I get a grinding/humming sound from what appears to be the passenger side of the engine bay. Now the strange thing is that it happens most of the time, but not all of the time. Like yesterday while experimenting a bit in a car park, the first few attempts got the sound, but for the rest of the afternoon and night, i got nothing, no matter how hard i gave the gas.

Experimenting a bit, slowly releasing the clutch (with no gas) and then when fully engaged, i give gas and will not get the sound. However, when giving a bit of gas while releasing the clutch, i will usually get the sound. However, it will last all but a second or two and the car will reverse with only the usual whining sound of a manual gearbox in reverse. Before people jump to the conclusion that its the clutch, driving and taking off in the forward gears is perfectly normal with no grinding/humming.

I dont have the time to get to a workshop until the weekend, so im throwing it out there to see if anyone else has had a similar issue and may know whats up. By the way, the car is 2004 1.8 manual focus (with the ib5)

Regards

Tom

BlackLS · 10-02-2009, 01:27 PM

Just guessing but perhaps its a halfshaft bearing? Or an engine mount.

Tj-zetec · 10-02-2009, 06:01 PM

perhaps check your ball joints and any other parts of the suspension and steering.

If something's loose it may be moving into a position when you reverse that creates the noise.
Basically grab the top of one of your front wheels and shake it. If you hear a knocking you've got something loose.

Oh and check your brake calipers too, if they're loose the could be making noises.

zetec · 12-02-2009, 05:43 PM

Quote:

Experimenting a bit, slowly releasing the clutch (with no gas) and then when fully engaged, i give gas and will not get the sound. However, when giving a bit of gas while releasing the clutch, i will usually get the sound.

My advice:

Baked beans will give gas and good sound

Pizza gives me gas but no sound and really stinks

If you want to give gas but not have sound, stick to Pizza.

Tj-zetec · 12-02-2009, 06:04 PM

Not very helpful.

Amusing, but not very helpful.
(onions do it for me BTW

)

More revs · 12-02-2009, 07:28 PM

I agree, please don't supply frivolous responses to serious questions.....

Now in my experience those noises are caused by backing into poles.... or other nationalities too slow to get outa the way.

zetec · 12-02-2009, 10:56 PM

Honestly I'm thinking an engine mount might be the culprit, it's possible.

fordel · 12-02-2009, 11:29 PM

I thought zetec's first answer was spot on.

I think its a great answer.

I think someone is grumpy with you zetec ;)

zetec · 13-02-2009, 07:09 PM

don't hate the playa - hate the game

Tj-zetec · 14-02-2009, 05:52 PM

I thought an engine mount too.

I really don't believe that it's the gearbox, which i would imagine is a relief to you.

I think you need to run it up on some ramps and go over everything that's a joint, a mount or anything else that will allow movement of the engine and drivetrain.