My '95 Miata developed a noticeable engine vibration followed by broken belts. Looks like the crankshaft pulley loosened. The key appears sheared off beyond the timing gear and the keyway has been damaged, but the key remains in the timing gear and the keyway there does not appear to have been damaged. There were no ignition problems or missing cylinders prior to the problem. The timing belt was replaced at 65K miles - now has 103K and I'm wondering if the crank bolt may have loosened up..

Question: Does the crank key actually do anything to secure the crankshaft pulley on the '95 models? The pulley is bolted to the timing gear and I see no notch on the pulley which would lead me to believe that the key actually fixes the pulley on the shaft.

If true, this leads me to believe that the problem could be fixed by replacing the key, pulley, belts and crank bolt, instead of having to try the early Miata Loctite fix on the keyway.

Anyone have any experience with this issue?

Any assistance or advice greatly appreciated!

BGG

 

The accessory belt pulley bolts to the spacer plate with 4 10mm bolts and the big 21 mm bolt secures the spacer place to the front of the crankshaft and sandwiches the t-belt pully in between right? I think the only purpose of the keyway extending out to the spacer plate is to index it to the correct position on the crankshaft so you will be able to check spark timing. If the keyway area for the
t-belt pulley is ok you should be ok there but just make sure you can align the accessory belt pulley and spacer plate so you can set base timing.