Land Rover Repair: Starting the Engine after a heavy rainfall, heavy downpour, light rainfall

Question
That is correct. I park it outside and it starts every single day when it is dry or even after light rainfall.  The problem occurs after heavy downpour. Is there a way I can get rid of the corrosion myself?  Thanks.
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-----Question-----
I have a 1995 Discovery and it starts and runs fine. In fact, everything was checked out about a month and a half ago.  The only issue I keep encountering is that, after a heavy rainfall (it rained about 15 hours straight here yesterday), the engine WILL NOT START.  The battery is fine...it just will not turn over.  Any thoughts on this?  Is this common?
-----Answer-----
If I understand you correctly - the car will not crank when wet.  Is that right?

If so, I suggest you look for corrosion in the battery cables, the fusebox behind the battery, and the grounds between battery and chassis and the engine and chassis.

Fusebox connection and ground issues account for 90% of troubles like yours.

Answer
You may be able to fix it yourself if you are handy.  Take apart and clean all the heavy wire connections at the battery, the fuse box, and the chassis.  

I guess it depends upon your level of mechanical skill.

Another good resource for tips on this is www.discoweb.org