New to the forums, found you all from google.

Was driving home today and my suby engine just stopped... no signs of trouble... and now won´t start again. It was making a loud rattle but my mechanic said it was just a tappet/lifter not getting enough oil and not to worry about it too much. He only suggested putting a lighter oil in it.
Other than that, no issues. Only done 177,000k´s and had all itś services done at regular intervals. Timing belt was done at just under 100,000k.
My gut is telling me it´s the timing belt though. I´m new to subies and not exactly sure how to test it. It does sound like itś only got compression on one side of the engine though.. if that makes sense?
If it is the Timing Belt whats the easiest way to make sure and how hard is it to change? If not.. any ideas?
It´s a 91´ carby EA81?
Thanks in advance
Ben