Warm Engine Noise (but not when cold)

[BlueBlood]

I have a 2001 Toyota Corolla, 1.8L 4 cyl engine, with 54K miles on it. When I first start the engine in the morning it purrs like a kitten. As it warms up I begin to hear what appears to be a "tapping" sound coming from the left hand side of the engine. I have taken the car to 2 separate Toyota dealerships and received 2 different "diagnoses". Both indicated the problem lies in the piston/rod/bearing arena and indicate that I need a new engine (at a cost of $4,000.00+ dollars).

To me this simply does not make sense. If the problem is the piston/rod/bearing area why do I only hear the noise when the engine is warm? These components being mechanical parts, I would think that they should be making the noise all the time - they don't. Also, from what I understand, bad bearings would destroy the crankshaft and lock up the engine fairly quickly. This car has been driven over 10+ miles on 3 different occasions since the "diagnosis". It hasn't locked up yet.

I'm hoping someone has dealt with a similar issue and can tell me what their resolution was. Replacing an engine with 54K miles on it with one that has 80K - 100K AND paying $4,000.00+ dollars to do it is simply not a very attractive possibility at this point.

[B-R-T]

It's not making that sound when cold, because metal expands when heated. That means your engine is not badly damaged yet. That's why you don't have any lockup occuring.

Milage doesn't mean anything if engine was built crappy. S*it happens.

If you haven't changed oil frequent enought it could damage main bearings too.