Lotus Elan and Lotus Elan Plus 2 Forums

I have an electric fan on the radiator and it does all the cooling I need. I kept half the fan on the water pump, just to keep some force on the water housing bearing. It seems to do it's job as I didn't have any problems for 10 years. Now I have a cartridge pump, but the mechanic says I don't need that fan, that the belt will do the work. What do you think?

Hello Fred,

The water pump bearing is mostly a radial bearing with limited thrust capacity. The fan only creates a very few pounds of axial thrust at speed. The belt provides almost all the radial load on the bearing. Most of the old two blade fans were poorly balanced and were hard on the water pump bearings.

Still you need some axial loading to keep the assembly from floating back and forth. Even if it's just a 0.001" of an inch eventually it will cause problems.

Fred Talmadge wrote:Still you need some axial loading to keep the assembly from floating back and forth. Even if it's just a 0.001" of an inch eventually it will cause problems.

Can't say I agree. My S1 Elan is in it's 31rst year of not running a pump mounted fan, without any water pump issues. Now that I think about it, all of my Loti had belt driven pumps without fans mounted on the pump. Replaced one water pump between them all (on my first Elan as it was leaking when received). Correct belt tension helps immensely of course.

Also, my Jaguar E is 17 years on the same water pump, and my last 3 daily drivers all ran belt driven water pumps without a fan. First two were over 180k miles on the original water pumps, the current one too soon to tell.

Remember this? Solves all your problems in one go.

TBG,

That is very interesting, and no, I do not remember seeing that before.

How is the water pump drive belt tensioned?

Richard Hawkins

I fitted a cartridge pump and electric fan 17 years ago.

Never had a problem,

I took the fan blades off the water pump about 40 years ago, did 10,000 miles a year in it for several years without problem. Eventually did a complete engine rebuild and replaced the pump as a matter of course, although it was still working ok, still not had and problems running without a mechanical fan.

Richard the water pump belt is just the right size and runs fairly loose so never wears out. All the tension is on the other belt that drives the alternator. One has to get a twin crank pulley turned up and an extended nose alternator pulley. Easily done and I have the drawings if anyone is interested. Already some in the USA I believe.

PS - I always change the pump at refresh engine time, and the clutch. Preventative maintenance they call it in aircraft wot I flew!

RichardHawkins wrote:TBG,

That is very interesting, and no, I do not remember seeing that before.

How is the water pump drive belt tensioned?

Richard Hawkins

The same as on the Europa
Alan

OK Alan,how is it done on the Europa?

I think it's with no way to tension just fixed length and that's why the Water Pumps last so long.
The Alternator is driven from a Camshaft i think.
Alan

After I posted the last comment, I thought the impeller adds axial thrust to prevent any problems. The single blade fan idea came from the previous mechanic/owner some 25 years ago. Seemed logical at the time, especially with the stock pump.

TBG,

Thanks for the explanation. It’s also called preventative maintenance and my industry, chemical process plant.

Now happily retired,

Richard Hawkins