Do i need change my engine belt in my 2001 subaru b4?

I assume you mean the camshaft timing belt? If it has never been replaced, the answer is "yes." Otherwise follow the service interval outlined in your service manual. Most small automotive engines from Japan recommend this T-belt be changed every 60-80 thousand miles. It should be changed every few years regardless of mileage due to aging. Do you have any service records on this vehicle? This is a good starting reference.

Many Subaru engines are "interference" type engines. This means if the timing belt breaks while the engine is turning, valves can come in contact with pistons and cause damage to these parts and/or the cylinder head. This is much more damaging and costly than replacement of the timing belt at a professional shop.

This is definitely one of those: "If it aint broke, go ahead and fix it anyway" situations. And I am not into fixing the unbroken! Except in this case.

Hope this helps you. Tater Todd