NA/B owners see this if you'd like to avoid an overheat

[davekmoore]

If you don't know when your water pump was last changed, do it now along with a timing belt and the ancillaries that go with the. Because the pumps can be like my one in the picture, even if they're not noisy, if the car is not overheating, if they're not leaking, and if the engine isn't using any water. The only clue you'll get is the heater only blowing lukewarm air. By all means try the other methods of improving the heater first, as they'll be cheaper.

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This from a '93 1.6 S-special with an alleged 157k kms, which the seller described as very well maintained, and my local garage promised me they'd fixed the lukewarm heater the day before. The heater was still lukewarm the next day. So both the seller and my (ex) garage lied. I caught the overheat before it did the engine, but not before it blew the head gasket.

What happens is, (I know now) assuming the car is used relatively gently, the hot water in the cooling system rises and the cool water drops, creating some circulation and some cooling, but no pressure, which is what is needed to reach the heater. This is called thermo syphoning. It seems it can't cope with 2.5 hours of motorway driving.

[93_Clubman]

Interesting Dave - can't recall hearing this, but certainly worth being aware of.

[bruce]

If this was common it would have been highlighted much earlier. People who do their timing belts would've noticed missing/damaged blades if they swapped the pumps.