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I have a 1999 NB8a and it has developed a raspy whining noise in the engine front end at around 1200 to 1600 rpm.

I have renewed both front drive belts, timing belt including idler and adjuster pulleys, water pump and checked alternator and compressor pulleys. There is a little play in the crank pullley but I don't think this is the problem as you would think it would get worse at higher revs but the noise goes away after around 1600 rpm.

It only makes this noise when hot but it tends to make a more subdued tinny sound when cold. The car runs fine and does not lack power.

I have taken it back to the original mechanic who replaced all the parts and he had the timing case off again recently to replace the idler pulleys as we were sure this would fix it.

Of course as soon as I got it home the noise was there again.

I have since taken it to another mechanic who couldn't diagnose it but seems to think the noise is coming from the top of the cam area.

I am spent heaps trying for a fix and I am now at my wits end.....any ideas?

Cam belt cover touching belt? Did you do the work yourself?

Dann

Uploading a video (or at a minimum, audio) of the noise will give people a better idea of what you're trying to explain.

NitroDann wrote:Cam belt cover touching belt? Did you do the work yourself?

Dann

No, my mechanic did all the work and assures me the the cover is clear of the belt. At first we thought the noise was the new cam belt 'bedding in' but the noise was still there after 500km so I took it back and that's when the idler pulleys were renewed.

The 2 front drive belts were removed at one stage but it made no difference to the noise.

MrRevhead wrote:Uploading a video (or at a minimum, audio) of the noise will give people a better idea of what you're trying to explain.

Thanks....I will try and upload a video tomorrow. The noise is similar to a coarse vibration and I first thought it was a heat shield or exhaust fitting vibrating but this has all been checked and the noise appears to be coming from the cam area.

Does it sound like a supercharger belt?

It may just be a little tight, which is totally acceptable.

Dann

http://www.youtube.com/watch?feature=pl ... Fvv20ijc_8

This is not mine but it sounds exactly like this at around 1500rpm. According to the video comments the timing belt is too tight and perhaps the noise will eventually dissipate....who knows... Don't know how a supercharger belt sounds Dann.

Did you fit any parts ordered from the UK? If so, it might be the standard pommie whine.

davekmoore wrote:Did you fit any parts ordered from the UK? If so, it might be the standard pommie whine.

Er......ha-ha??

After further investigation and following 'Mike's Place' Miata details on utube I am pretty sure new timing belt is too tight. Can this cause any damage and will it loosen over time?

After further investigation and following 'Mike's Place' Miata details on utube I am pretty sure new timing belt is too tight. Can this cause any damage and will it loosen over time?

I may need to take it back and get it adjusted but I was under the impression that the adjuster pulley did this automatically??

talk to the mechanic - I also do not understand how the belt is overtightened. I also subscribe to the view that some belts are noisier than others-ie not all belts are the same. If it's a whine it could be the belt. If it does not intrude too much then maybe just ignore it. Another possibility is a bearing eg water pump or alternator??. You might be able to pick it up with a stethoscope. It seems the mechanic has been thorough.

Mr Morlock wrote:talk to the mechanic - I also do not understand how the belt is overtightened. I also subscribe to the view that some belts are noisier than others-ie not all belts are the same. If it's a whine it could be the belt. If it does not intrude too much then maybe just ignore it. Another possibility is a bearing eg water pump or alternator??. You might be able to pick it up with a stethoscope. It seems the mechanic has been thorough.

Yeah----thanks. Pretty sure after talking to Mazda & other mechanics that the belt is too tight. All have now told me that it should stretch a bit over time and the noise will go away. If the noise is still there after 1000km or so I will get a mechanic to slacken it off a bit. As you know that is a pain coz you have to remove rocker cover ($30 gasket), drive belts cam cover etc. etc. to get at the cam belt and it's quite costly ($250 +).

Water pump and 2 drive belts are new and alternator and a/c compressor bearings have been checked with stethoscope and they are ok.

When you google this problem you find a hell of a lot of MX5 owners have had the same noise problem from the new cam belt but they do not appear to have solved it....go figure!

It's fine to re use a cam cover gasket if it's reasonably new.

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sailaholic wrote:It's fine to re use a cam cover gasket if it's reasonably new.

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Yeah....I know but it wasn't the cam cover gasket, it was the rocker cover gasket, and the new one was apparently damaged when it was stripped down for the second time as it started leaking so I had to fit another new one. sob.....