Hi all. I had my 320 convertible serviced a couple of days ago and had a new cambelt kit installed at the same time, along with the valve clearances adjusted (plus new water pump and new fuel pump). I was expecting a much quieter, smoother running engine to be the result of the valve work - unfortunately it sounds just the same (so has the work been done or not?!) except for one thing; there's a whine coming from the cambelt. Has it been over-tensioned and is this going to cause problems? When I mentioned it to the garage owner he just said to come back if it was still whining after 500 miles...
Any advice appreciated.
Post-service blues
Moderator: martauto
Firstly, my answer is not gospel - you should be very careful with the cambelt!
I would think that the cambelt is probably ok, as they can take a few miles to bed in properly - they'll be super tight when brand new, and over a few miles will stretch ever so slightly. It's usually recommended to re-tension it after a few hundred miles anyway I think.
Are you sure it's actually the cam belt? Could it be one of the other belts - PAS or alternator maybe? Sometimes the toothed nuts that go onto the adjusters that hold the PAS pump and alternator in place can become stripped, so the PAS pump and alternator won't stay in the perfect position - naturally this then makes for noisy "fan" belts.
Simplest way to check if it's the cambelt making the noise is to remove the other belts, start the car and see if the noise is still there.
I would think that the cambelt is probably ok, as they can take a few miles to bed in properly - they'll be super tight when brand new, and over a few miles will stretch ever so slightly. It's usually recommended to re-tension it after a few hundred miles anyway I think.
Are you sure it's actually the cam belt? Could it be one of the other belts - PAS or alternator maybe? Sometimes the toothed nuts that go onto the adjusters that hold the PAS pump and alternator in place can become stripped, so the PAS pump and alternator won't stay in the perfect position - naturally this then makes for noisy "fan" belts.
Simplest way to check if it's the cambelt making the noise is to remove the other belts, start the car and see if the noise is still there.
Tappy top end could be injectors rather than tappets - not really anything to worry about if the running is unaffected. There is also a school of thought that suggests setting the clearances slightly wider than factory for better running, at the expense of a little 'tappety' noise. Frankly, M20s are never especially quiet in this department in my experience, though loud clicking may need further investigation.
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