I've heard that having your timing too far advanced (I think) can cause your exhaust manifold to glow hot. Something about unburnt fuel making it's way into the exhaust. That would be the first place I'd look. I would also flush your radiator, and refill with about a 50/50 mix, and be sure there are no air-bubbles in the system, as that can add to heating problems. Checking the fan clutch would also be on my list of must check items.

Any noise from the engine to suggest a waterpump problem?

Good luck, and let us know what you find.

Erik