Nasty noise diagnosis

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Wavesong
Joined: Sun 21 Dec, 2014 18:46
Posts: 89

  Z3 roadster 2.0

Nasty noise diagnosis

Post by Wavesong » Fri 11 Sep, 2015 19:31

Hi Guys. I went to put the Z away tonight (year 2000, 2.0) and at 1500 to 2000 revs, there was a nasty noise, rather like a rattling heat guard though I checked those. The noise lessened as the engine warmed but never went away. I notice some slight sideways play in the fan so possibly the viscous coupling? I had two new front tyres fitted this afternoon and the car ran and sounded fine on the journey home. Any ideas to stop me fearing the worst please? The engine sounds completely normal at tick over. Noise comes in at 1500 to 2000 and gets worse if the revs are increased.

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colb
Joined: Sat 05 May, 2012 23:46
Posts: 566

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Nasty noise diagnosis

Post by colb » Fri 11 Sep, 2015 20:14

New tyres fitted, seems a coincidence with the noise appearing so soon after, whip the wheels off and check there is nothing trapped between the disc and the disc back plate that could cause the noise when the wheels are turning.

Colb
Colb
1999 BMW 1.8 Z3
1998 Honda Deauville NT650V

Wavesong
Joined: Sun 21 Dec, 2014 18:46
Posts: 89

  Z3 roadster 2.0

Re: Nasty noise diagnosis

Post by Wavesong » Fri 11 Sep, 2015 20:44

Yes it is a coincidence but, the noise is there when stationary and wasn't there on the way home. There has though been a strange groaning noise on pulling away, especially when turning, for the last few days which may be connected. I will take the fan belt of tomorrow and see if this cures the noise which will then isolate it to the things driven by the belt. Could be power steering pump? Is that driven off the fan belt too? Power steering fluid is up to level.

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colb
Joined: Sat 05 May, 2012 23:46
Posts: 566

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Nasty noise diagnosis

Post by colb » Fri 11 Sep, 2015 21:06

Sorry misread thought it was on the move when it happens.
Your idea of removing the belt seems like the way to go in order to pinpoint the cause, don't rule out any idle bearings in the belt route being the cause.

Colb
Colb
1999 BMW 1.8 Z3
1998 Honda Deauville NT650V

Wavesong
Joined: Sun 21 Dec, 2014 18:46
Posts: 89

  Z3 roadster 2.0

Re: Nasty noise diagnosis

Post by Wavesong » Fri 11 Sep, 2015 21:17

Well it does kind of sound like a bearing rattle kind of noise so the tensioner may be the cause of the problem which in turn may be causing the groaning sound which may be a result of the belt tension on the power steering pump. So, first job tomorrow after breakfast will be to remove the fan belt and fingers crossed for a quiet engine. No doubt I shall be reporting back for further help but thanks for the guidance so far.

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2115

  Z3 roadster 1.9

Re: Nasty noise diagnosis

Post by Del » Sat 12 Sep, 2015 10:13

Where is the noise coming from? Is it from the area of the catalytic converter (they can break up internally with age) - if you give it a firm nudge, the rattle will be obvious. Another common issue is the little metal exhaust bracket at the gearbox area - the bottom section rusts away with age and thus causes a loud metallic/vibration noise when revving - easy fix for under £20.

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BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2220

  Z3 roadster 1.9

Re: Nasty noise diagnosis

Post by BladeRunner919 » Sat 12 Sep, 2015 10:17

If you have movement in the fan I would strongly advise against driving the car - if the fan fails you will probably end up with holes in the radiator, water all over the floor and even a dent in the bonnet. You also risk damaging the engine if it dumps its water. Could also be the water pump bearings are going, with a similar outcome.

Wavesong
Joined: Sun 21 Dec, 2014 18:46
Posts: 89

  Z3 roadster 2.0

Re: Nasty noise diagnosis

Post by Wavesong » Sat 12 Sep, 2015 18:55

I started this morning with changing the rear disc pads which all went well. Then, with heart in mouth and after a very careful inspection under the bonnet and under the car, started her up. No nasty noise. Left ticking over and warming up for ten minutes and then increased the revs gently. Still no nasty noise. Drove it round the block and all fine. So, I am somewhat confounded and can only assume that, given mechanical maladies tend not to be intermittent, (unlike electrical) that there must have been a piece of debris somewhere that the fan blade was catching and that in the night, the fairies removed it for me whilst forgetting to leave a note to that effect. Fan and coupling has just the right amount of resistance to it and the movement I thought I detected was just the blades moving under the pressure I was applying when trying to detect play. Also, no perceivable play in the belt tensioner. All fluids are good and no dash warning lights. I have a trip planned for this week which will clock up some 900 miles so if a problem remains, this should shake it out and I will have to deal with it as it arises. This all comes from trying to use the Z as much as possible rather than leave it languishing prettily, in my garage. :D

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BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2220

  Z3 roadster 1.9

Re: Nasty noise diagnosis

Post by BladeRunner919 » Sun 13 Sep, 2015 09:47

That's good news but, at risk of sounding like a pessimist, if there's any chance the fan was catching on something I would replace it. A weakened blade that breaks will cause you a world of upset. Or, if the car has an auxiliary electric fan, just remove the viscous one permanently.

Wavesong
Joined: Sun 21 Dec, 2014 18:46
Posts: 89

  Z3 roadster 2.0

Re: Nasty noise diagnosis

Post by Wavesong » Sun 13 Sep, 2015 15:38

Yep good advice and I will check the fan blades carefully before setting off tomorrow however, I did find a self adhesive bar code label on the floor under the car :shock: This is all it would take to make the noise I had and, on stopping, probably fell down to the garage floor. May just be grasping at straws but I am struggling to otherwise explain it.

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Gordon13
Joined: Tue 16 Sep, 2014 19:45
Posts: 58

  Z3 roadster 2.2i

Re: Nasty noise diagnosis

Post by Gordon13 » Sun 13 Sep, 2015 17:10

I had much the same issue in the summer.
Bearing noise that was there one day and not the next, hard to pin down, and only there when cold. Went away as it warmed up.
I suspected, as has been suggested, a water pump but couldn't detect any play.
That was until I removed the belt, then the fault was obvious, lots of play in the pump.
Changed it pronto and no more noise.
I don't think I would risk a 900 mile journey with a dodgy pump, so worth checking
Image

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leahandsteve
Joined: Sat 29 Sep, 2007 21:02
Posts: 122

  Z3 roadster 1.9
Location: Stokenchurch (J5 M40)

Re: Nasty noise diagnosis

Post by leahandsteve » Sun 13 Sep, 2015 19:39

I had a similar noise on my E36 M3, was coming and going and changed with engine noise.

Finally traced it to the plastic undertray, part of the fixings had broken away causing the undertray to rub against the air con pulley.

Wavesong
Joined: Sun 21 Dec, 2014 18:46
Posts: 89

  Z3 roadster 2.0

Re: Nasty noise diagnosis

Post by Wavesong » Sun 20 Sep, 2015 12:08

Well I had my week away and clocked up the anticipated 900 miles. The noise came back just once as I was parking and, as I finished parking on a hill, it stopped and hasn't come back since. I think there is a link between the new front tyres which I suspect, owing to their new deep tread, are chucking up road debris into the plastic tray in front of the radiator.

On another point, I have owned the car since last December. To date, I have all green service lights lit and in that time and two thousand miles, none have extinguished. Am I right thinking that these go out with the passage of time as well as the miles covered. I am starting to think the service indicator isn't logging anything. Not a major worry as it will get a thorough service next month regardless and I will buy a reset tool for the indicator. Any thoughts on this?

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