mx5cartalk.com

I changed the water pump last week so I thought id do the timing belt too. At the time I just let the spring tensioner pull it in and tightened up the tensioner there. Then I noticed the faint whirring noise. Just got it down again to loosen it off but I am unsure of how tight it should be/how much to loosen it off for fear of having it too loose.

Or is the whirrr normal? do I just ignore the whirrr?

After doing the appropriate crankshaft rotations to the tension set point, you loosen the tensioner pulley bolt and let the tensioner pulley spring set the tension. Then tighten the tensioner pulley bolt to spec. Then, after the correct number of turns, all the timing marks should line up and the belt tension should be correct (about 9mm deflection between the cam sprockets is a rough check).

As for the whirring sound............ Could be the new water pump.

I checked the water pump first. I have done the tension as you said and the belt was hell tight. I have just set the tensioner only slightly back and it feels good and the whirring is gone. I thought it very strange to have it too tight just by the tensioner alone. I willl check the deflection between the cam gears as you say.I reckon it would have to be pretty close now anyways.