Lotus Elan and Lotus Elan Plus 2 Forums

Maybe at those sustained revs, the mixture is too lean?

All the blockage ahead of the radiator is in the correct original position, you have a larger than original radiator...
Is a high of 95 deg really a problem?

Ted

I am slightly surprised to see that you have an engine driven fan as well as an electric one. Are engine fans standard on Sprints in the warmer parts of the world?

There was a problem with some cars in the old days when it was possible to refit the engine driven fan the wrong way round such that it pushed air back into the radiator, it was not a problem when ticking over but became apparent when driving. Is this a possibility?

HTH

You might be overthinking this, try a change of thermostat and while doing it you can check the temp rating of the existing one and its function.

I just resolved a problem on my road car by changing the stat but not until after testing it and deciding it was OK, changing the temp sender etc etc, was the stat all along, just a different (partial) failure mode than what I am used to.

Have you checked that the sender & gauge are reading correctly? I found on my S4 SE on Stromberg & narrow radiator with original electric fan that in traffic the temp will go up to 100C or higher. One small thing that I found actually made a difference was to have the overflow bottle with the correct rad cap.

GregZ - actually my Strombergs are running very rich.

PhilH - I really don't know the answer to that, whether running at 95 degrees is problematic or not? I suppose if it doesn't "run away" and keep going higher, i would be OK, but it just makes me very nervous watching the temp gauge and worrying about overheating, even though it hasn't yet.

HTH - I added that plastic fan to the water pump pulley myself. It did not come equipped that way originally. Fan is positioned correctly and pulls air from the front through the radiator, however slightly. I figured every little bit helps!

Chancer - good point, however when i start up cold, the temp comes up to 85-90, then i can easily see on the gauge when stat opens to let cool water in, the gauge drops down visibly. It does that up & down thing continuous, albeit in smaller wiggles (letting in cool, closing off, letting in, closing off, etc.) The stat was brand new. The stat i replaced apparently wasn't the problem since the same results occur with both stats in place.

Keith - I have my overflow bottle in place and it does "suck in coolant" as needed, and expand into bottle as necessary. Appear to be working as designed.

Thanks everyone for all the helpful suggestions and guidance!
Maybe i am over thinking this since in reality, it runs cool while in traffic and responds with electric fan switch turned on. That should be the greater concern and it doesn't worry me that way, just the constant highway speed on a hot day for a prolonged period.

If all else is confirmed as correct/good, check the water pump pulley isn't smaller than std. (or the crankshaft pulley isn't larger) If it is, it will speed up the pump, which can be an advantage at lower RPM's but at higher RPM's the coolant can be forced through the radiator too quickly, not allowing enough time for it to be cooled sufficiently with the somewhat limited airflow through an Elan, it's just not in the radiator long enough. May sound daft, but I've encountered it before, & it's not uncommon for larger pump pulleys to be fitted to race engines that run at consistently high RPM's for that very reason.

Tim

does anyone know what the correct original sizes are for the pump pulley? the crankshaft pulley? the alternator pulley (if that matters)?
I just measured mine (outside edge to outside edge) and the crank pulley is 4 inches and the water pump pulley is 4 1/4 inches.

Hi Ted
Your water pump and crank pulley diameters sound correct. The alternator pulley diameter does not matter as far as the cooling system goes.

i would not worry about 95C when high speed cruising on a hot 35C day. if it gets consistently over 100C I would investigate further and over 105 degrees I would start to worry.

cheers
Rohan

Had a similar problem with a S4. Checked out the cooling system, larger radiator, etc. Problem was worn bottom end bearings. So how's your oil pressure?

>>
PhilH - I really don't know the answer to that, whether running at 95 degrees is problematic or not?<<

It is not a problem!

good lord, I have had my car up to nearly 120C accidentally and it did not overheat

see if there is supposed to be foam around the radiator if it creeps up

You are making horsepower, horsepower =heat it gets hotter

95 degree is not a problem

EVER!

If you get over 105 and it still moving upward, perhaps we can talk

Joe7 - excellent oil pressure, thanks!

Two other points for what its worth

1. confirm that your temp gauge is accurate - this was raised in an earlier suggestion - I found myself chasing ghosts before I realised that the temp was fine and the gauge was over reading

2.If all else fails, consider Evans waterless coolant which is supposed to run at lower temps. I realise that this deals with the effect rather than the cause but it might keep you going until your next rebuild - if this turns out to be the cause.

Good luck
Gavin