Hi there,
Now you won't want to hear this but.....
if the pump is leaking then stop driving the car because at some point it's going to fail very, very badly and that could easily leave you stranded. Even worse, if you're in traffic and don't notice the temperature gauge then you'll have every chance of damaging the engine. The pump relies on a mechanical seal to hold in the water and if that goes (as it did the first time round on mine) then you lose water very rapidly and once the level is below the thermostat, you don't get a correct reading until far too late.
If there's play in the pump pulley (remove belt, pull/push) then it's the bearing going and that will drip until one day it goes catastrophic and water starts spraying everywhere (as per my Elan). If you have any odd noises at all from the pump on starting/revving then you're about to enter that world. Reducing tension in the belt isn't going to fix that one I'm afraid.
It is practical to change the front cover without pulling the engine, I've done it three times now, but I've always removed the head & sump pan. In theory you could get away with just dropping the sump and IIRC that was the method in the very first Elan manuals in '63, but making a seal is very difficult with that method and hence the current advice to remove head & sump. As BDA says, I wrote up the last event and posted on the forum (
http://www.lotuseuropa.org/LotusForum/index.php?topic=4128.msg44085#msg44085) and at the end of that there's some notes on alternative belts which have varying degrees of tension when fitted.
As for alternatives, I'm not personally convinced on the cassette options because in normal use the OEM pump doesn't fail that often. Lack of use causes the seal to stick, that's one failure method with a low mileage car, and over stressing the belt is supposed to be another. But there's no option to overstress on the Europa, it's a fixed belt.
Mike Walters said at a Club Lotus seminar that pump failures rarely happened on the Europas but the Elans, with the option to overstress the belt, did have failures. One thing that stood in my mind was that he said most folks over tightened the belt and to pump water around you needed very little force on the pulley. Basically keep the belt just tight enough not to slip and there's enough friction to drive the pump.
One thing that does appeal to me is the electric pump because you then you have the option to circulate after the engine stops and that might prevent heat soak temperature rise in the head gasket area. Given how long the TC engines last I'm not sure that's essential on this engine, but it's a thought.
Brian
