Strange Scraping/whistling/rattling Noise From Mi

[GLPoomobile 958]

2 weeks ago I was driving the Mi down to Dan Taylors workshop, and on the M23 I noticed a funny noise between 80-90mph. I'd not had the car at that speed in over a year. It was difficult to hear properly over all the other noise, but it sounded like it was coming from the front n/s. I can only describe it as sounding like a light (but loud) scraping, similar to the sound you get when you spin a front wheel and can hear the brake pads just touching the disk.

 

So playing around for those few minutes, it was not so bad cruising, and got worse accelerating, always above 80mph. Then I tried dipping the clutch and coming off the throttle, and it disappeared. I assumed it was probably gearbox related.

 

Sods law, Dan couldn't hear the noise when I left the car with him.

 

So I picked it up today and for the first hour of the journey home I couldn't hear anything. Eventually I found myself on the M23 again and took it up to 90mph and at first there was no noise. Then after a while I could just about hear it again, more like a whistle like wind coming in through the window seals. It slowly got louder, and also changed slightly to a more rattly noise.

 

So I started playing about again. Dipping the clutch and coming off the throttle it would disappear. This time it was present from about 55mph onwards. Then I tried dipping the clutch but holding the engine at the same revs, and the noise was still there. Comes in at about 3.5k rpm. With the clutch in I was revving the engine up and down and it was coming and going, from 3.5k rpm it was there and would get a little louder as the revs increased. It would also come and go for a few minutes at a time. Then at traffic lights I noticed I could just about hear it very faintly at idle.

 

The problem is obviously starting when it's warmed up. I did try and listen under the bonnet when I got home, but couldn't hear it. Think I'll need a 2nd pair of ears and eyes on this one.

 

Anyone got any ideas?

Edited November 22, 2009 by GLPoomobile

[maxi 36 1 Cars]

Very strange, have you checked things like the alternator belt isnt rubbing on the cambelt cover?

 

Maxi

[GLPoomobile 958]

Haven't checked anything yet. It was dark when I got home. I did wonder if it was maybe something along the lines of the cambelt rubbing on the cam cover, but it sounds like it's coming more from the middle of the car, or the passenger side.

Edited November 22, 2009 by GLPoomobile

[Richie-Van-GTi 74 2 Cars]

Since its only when warm I would check things that are adversley affected by heat such as oil and coolant parts. I would suspect possibly the input shaft bearing on the gearbox is a touch noisy and only audible when the oil has thinned down with temperature. If it was engine oil related it should transpire much sooner as the oil gets to temperature faster.

[GLPoomobile 958]

I'm clueless when it comes to the gearbox and clutch etc, so please enlighten me. If it was the input shaft, would it be affected by changing revs even with the clutch engaged? I know I've got the usual rattle that they always seem to have, which I believe is the clutch release bearing (going by what others have said on here).

[Richie-Van-GTi 74 2 Cars]

Input shaft is the main shaft that the clutch sits on, this would be spinning whenever the engine is spinning unless the car is parked in gear with clucth pedal pressed.

[GLPoomobile 958]

Input shaft is the main shaft that the clutch sits on, this would be spinning whenever the engine is spinning unless the car is parked in gear with clucth pedal pressed.

 

Sorry, I'm in dufus mode at the moment, so having trouble getting my head around that. The end bit of that statement has me confused. This is doing it a} whilst driving, revs over 3.5k rpm, clutch out and in gear obviously b} whilst driving, clutch in, and revs still above 3.5k rpm and c} quietly at idle when stopped but not sure if I was in neutral or if still in gear and clutch in.

 

Would testing it with the engine over 3.5k rpm but the clutch out and gearbox in neutral show anything?

 

Would it be worse if a little low on gearbox oil? I'm sure the level should be right as I topped it up a few weeks ago, but worth checking if it's a possibility.

 

And if it is the input shaft, how much of a worry is it?

[DamirGTI 344]

Diff bearings perhaps ?!

 

Damir

 

EDIT : does this sound appears only whilst driving or is it present when standing still as well , i.e. at idle ?

Edited November 22, 2009 by DamirGTI

[taylorspug 7]

I really dont have a clue on this one, indeed ive not even heard the noise in question after driving the car. At idle and revving it sounds like one of the sweetest MIs ive heard, and when driving it it just sounded like normal too! Drove fine aswell, near as damn it perfect in fact (you have a very well put together car Steve!).

 

Its not the wheel bearings or shafts, i did give them a check and they seem fine to me. Gearbox also seems sweet. I know it sounds weird but ive found sometimes the exhaust manifold can throw up some very funny noises at certain speeds and RPMs, almost like a grinding sort of sound. My MI did it, and my '6 does to a certain extent. I dont really notice it though as its not a fault as such. Could be worth thinking about especially as your reangled manifold doesnt look like the best effort ever.

[GLPoomobile 958]

especially as your reangled manifold doesnt look like the best effort ever.

 

My DES Developments re-angled manifold you mean. Just to clarify.

 

Well I'm defo not imagining this one. I know I've had some panics over noises that may or not be there, but this one is definite (see Tesstuff, I am making an effort on that one ), and it is new. As I said earlier, I'm going to have to get some extra ears in on the job for this. But I will be checking it over in daylight for any obvious signs of things rubbing etc

[jackherer 543]

So I started playing about again. Dipping the clutch and coming off the throttle it would disappear. This time it was present from about 55mph onwards. Then I tried dipping the clutch but holding the engine at the same revs, and the noise was still there. Comes in at about 3.5k rpm. With the clutch in I was revving the engine up and down and it was coming and going, from 3.5k rpm it was there and would get a little louder as the revs increased. It would also come and go for a few minutes at a time. Then at traffic lights I noticed I could just about hear it very faintly at idle.

 

I once had a fairly new timing belt tensioner go bad on an Mi16 and reading that reminded me of it...

[welshpug 1,666]

Had something similar on my brother's Saxo, timing belt was like a drumskin and got worse as the engine warmed up, thankfully no damage was found and it hadn't been run like it for very long.

[GLPoomobile 958]

I'll try and get the belt cover off and have a look then.

[taylorspug 7]

My DES Developments re-angled manifold you mean. Just to clarify.

 

Well I'm defo not imagining this one. I know I've had some panics over noises that may or not be there, but this one is definite (see Tesstuff, I am making an effort on that one ), and it is new. As I said earlier, I'm going to have to get some extra ears in on the job for this. But I will be checking it over in daylight for any obvious signs of things rubbing etc

 

Yes, that one!

 

No im not saying you are imagining it mate! Problem is all 205s make different noises to a certain extent, especially converted ones. I tried pretty much everything to make it happen and drew a blank.

 

Anyway i did have the belt cover off on the 'find the noise' quest, and it was tensioned fine. Usually tight belts on MIs only take a couple of minutes after start up to start making a right racket too. The dry tensioner is a good thought though, as that could take a prolonged period of running (ie over an hour) before it started to kick up a fuss.

[GLPoomobile 958]

The noise took a long time to kick in again, but once it did start it was almost permanent above 3.5k rpm on my long drive to/from Scotland this weekend.

 

It's now become a more consistant sound, and I've decided it sounds very much like a nut rattling. So I reckon the engine frequency might be causing a loose nut to rattle. Whether that is in the engine bay or behind the dash I'm not sure.

 

There is one thing that I'm going to pursue first of all though, and that is the gear rods (Miles' ones). My gear rods have a certain amount of free play (although they are fixed firmly as they are designed to be). I can imagine them making the right noise if the were vibrating. I did give one of them a wiggle in the car park on the way back and the noise seemed to disappear for a while. So I'll see if I can fix them firmly and if the noise then stops.