Over heating conundrum

[SVP]

Hi all not ben an owner that long and not that good technically, but understand the concepts, anyway.

Got a Sumo with RV8 (standard 3.5, Holly carb and Offenhauser mnifold) and has been working well for the last 3 weeks (as long as I've owned it - bought from dealer), on Saturday took it out for a little spin and while out watched the temperature gauge rise over the 80/90/100 to 110 (while driving luckily hadn't got far and took it home gingerly).

Checked water in expansion tank (fine about half way up tank - standard Pilgrim tank) checked oil, no emulsion.

Yesterday thought I'd start it and leave it running in drive to see what happens, slow build up to 80-85 (as expected), sits there for about 4 to 5 mins, then the fans come on volt meter drops from 14V down to 11v and the temperature gauge immediately up to 120, turned engine off, fans still running, temp gauge still reading 120, as soon as fans stop gauge down to 0. All the pipes are getting warm/hot so presume not a blockage, water in expansion tank also getting hot.

As it was working fine I can't quite seee whats changed (apart from something broken), car was factory built at Pilgrim 1999, so I suppose it should be farily well put together.

Any thoughts on whats going on and any thoughts on a good place to get it sorted in north Surrey (Esher) area.

Any views on whats going on greatly appreciated.

SVP

[andicole0]

Could it be an electrical problem over driving the temp gauge? Does the gauge really go immediately to 120 as soon as the fans cut in? Engine temp would rise smoothly, not in sudden steps.

If you have an adjustable thermostat on the fans set it lower to see if the temp gauge really does jump to 120 when they cut in.

Andi.

[neil50]

I would also also guess at an electrical fault with the gauge system. The temp wouldn't jump 40 degrees immediately, don't know af anything that powerful that would superheat that quickly,unless you have a flux capacitor fitted and are running on nulear power

[SVP]

Thanks guys a little more reassuring, that it might just be electrical fault, i'm still slightly mystified as to why driving it it didn't do the immediate jump, will look at what's going on with the gauge, it really did do that immediate jump. Can't alter stat on fans not adjustable. I could always disconnect fans just to see if there's a slow and steady rise on gauge though (of course remembering to re connect them).

[craggle]

You shouldn't really see a voltage drop once the fans start. 11 volts is too low and is draining the battery.

Maybe the alternator is playing up?

Craig.