Metallic rattling noise with throttle (load) affected by position of steering.

[jeremy156]

Here's an odd one worth a punt around the forum... over the last month or so there's been a horrible rattly noise when I accelerate (best way I can describe it is being like rice being shaken around in a kitchen collander might sound.... sort of rapid scratch and rattle, fairly loud but not "heavy"). At first I thought it might be the sound of escaping air as I'd recently dis-assembled and re-assembled the air filter housing, but I've triple checked everything is in place and no change. I also wondered whether it was the sound of the ceramic cat rattling around, probably not though. The sound is absolutely linked to engine load, i.e. push the accelerator and the noise comes is proportionally, but I can't really hear much when stationery.

What I noticed yesterday was a curious link between the noise and steering wheel position. Straight ahead I get the noise, turn the wheel slightly right and it gets a lot louder. Slightly left of centre and it's almost silent. Could this mean something's getting caught up in the steering or something? Any ideas?

 

[Dieselman]

Sounds like either exhaust/manifold leak or Cat rattling and the stering gaiter is split allowing noise into the cabin.

 

[jeremy156]

Hey Dieselman, fast response, thank you!

That certainly sounds a convincing argument - the steering movement just opening a gap for the sound to come through, but the source sound having nothing to do with the wheel position.

Apologies for being niave, but what and where is the steering gaiter... i.e. how to do I find it to check if it's split? Is it something in the cabin or tucked into the deep recesses of the engine bay?

Thanks,
Jeremy

 

[BlackC55]

I would be looking at the CAT's too.

Get underneath the car and give them a tap.

On your model car they are very common to break up.

 

[whitenemesis]

Does this model have the metalic bellows connection between the manifold down pipe and the exhaust?
This has been implicated on other models with this sort of rattle. Solution is to very slightly ovalise the bellows with some sort of clamp.

 

[Dieselman]

Apologies for being niave, but what and where is the steering gaiter... i.e. how to do I find it to check if it's split? Is it something in the cabin or tucked into the deep recesses of the engine bay?

The gaiter is the rubber concertina gaiter around the column where it exits the firewall into the engine bay.

Look from under the bonnet and you should see if it is split.

 

[jeremy156]

OK, I removed the trim cover under the dash and saw where the steering shaft disappears towards the engine. Given the adjustable steering wheel and the way the joint is off-centre to accommodate that, I can see how the steering wheel position moves the linkage from side to side and this could explain the opening or closing of a split/tear.

A quick grope from within the car seems to suggest everything is intact and peering in the bonnet shows a fairly solid looking rubber concertina with a metal shield around it. I can't reach down from the top, so will have to try from underneath when I can jack it up.

I remember when the centre and rear of my exhaust was replaced recently, the guy was whacking the cats and suggested the right-hand one was a bit iffy, so I'm fairly sure that's the source of the rattle noise and will have to be replaced soon. The steering gaiter "noise leak" is apparent now as it's making the rattly cat symptoms more obvious, so would be good to get that fixed and block out the rest of the noise coming in, right?

On the subject of the cat, OK to replace just one, or must they be done in pairs?

 

[DrNick]

A quick way to check if the sound is coming throught the gaiter is to stuff a sock into it from inside the cabin. Worked on mine!

 

[Dieselman]

A quick way to check if the sound is coming throught the gaiter is to stuff a sock into it from inside the cabin. Worked on mine!

I'll try it with the Wife..

 

[Dieselman]

On the subject of the cat, OK to replace just one, or must they be done in pairs?

Just do the one.

 

[Rumble]

Hmm before you go to the expense of replacing the cat, try cleaning your throttle body ie the butterfly valve, as residue can build up on it and give a rattling tapping sound on acceleration. Its a 20-30min job and costs a few quid for the carb cleaner spray to clean it! You can do it insitu just remove the air intake housing til you see the valve and spray away unitl its clean!