I am convinced that the bloke who designed the air inlet for heater on a 300Tdi Defender must have shares in the company who makes the electric motors for the heater fan.

It seems to be designed to fill with water and destroy the fan motor.

When I first bought mine, the fan motor was just about seized because it had a litre or two of water in it.

The drain on the bottom was full of mud. I cleaned it out and used a lot of WD40 squirted everywhere I could get it in and around the motor. After a lot of rotating by hand, It started working again and is still OK two years later.

A few times during that time I have given the drain a bit of a squeeze to try to stop it happening again.

However, today when I pulled it off, it was just about blocked with mud again. A heavy downpour would have flooded the fan motor again.

My reason for putting this in The Technical forum is that I suspect that unless other Defender owners manage to stay clear of dust and other pollutants, it might be wise to have a really good check fairly often. That can be done by removing the plastic grill and reaching down to feel how deep the mud is in the bottom of the air intake.

I know a couple of other Defender owners seem to have the same problem in the last couple of years.