Ok, so I've been out in her twice now and the temp gauge is reading after about 20 minutes 110 and even creeping up. So I pull her back into my drive and check the cooling pipes, the top rad pipe (which goes to the temp gauge on the block) is roasting hot and the bottom pipe is cool, can easily put my hand on it. So I turn the engine off and all of a sudden the bottom pipe gets really hot, I take once the engine is off the coolant flows back into the expansion tank? Could it be that the heater matrix is blocked (air lock) I think that needs investigation? Also I've just taken the pipe off of the block, the one that goes to the heater matrix and that was empty, no coolant, shouldn't that be full? And I have an overflow pipe at the front off the rad, that just seems to pour coolant constantly, that can't be right?

I'd be trying a replacement thermostat first.

Ok its a more modern car but we had something very similar on a mk4 golf recently and the tstat was the cause.  At least you can chuck the lotus one in a pan of water and boil it up  to see if its working.

you can get lower temperature thermostats btw

Ok my hunch was it is a faulty theromstat, think I'll get one as they are cheap enough, process of elimination... anyone know if I can find one online? SJ's kills you on postage for one off items.

This any good?

http://m.ebay.co.uk/itm/300599668497?cmd=VIDESC

If you are getting a new stat anyway, pull out the old stat, drill a 10mm in the plate and refit to check if the performance is any better. It could just as easy be the water pump.

Bloody'ell that was hard work, 2 hours to get the sod off, that bloody little bolt behind the pully, I couldn't tell you how I managed it, but got the barstuward off! So the waterpump is off but the good news is that it looks in perfect condition and very little end play in the bearing, so we can rule that out. It must be filling the system correctly, must be doing something wrong. I have found in the manual the correct procedure to refill so I'll give it another go. The thermostat also looks tip top so and to be honest the coolant come out clean, still blue, and no sludge I could see. Has to be an air lock?

Before you start to nail that all back together, source an allen headed bolt to replace the one which sits behind the pulley. It saves so much time for future fiddling.

As for the thermostat, you can't tell solely from a visual inspection whether they are any good or not. Yes, you can do the dunk test in a jug of hot water, but given their low cost it's usually more decisive to just replace them with a known correct part.

I agree on the thermostat, only problem is, the housing is practically welded to the waterpump. I've tried to get them off but they are bending my 5mm allen keys! Good idea the allen bolt behind the pully, that is a sod to get off.

 And I have an overflow pipe at the front off the rad, that just seems to pour coolant constantly, that can't be right?

 

Have you got a photo of this? Doesn't sound right to me......

Have a look at this, see what you think? It's that top small hose just next to the otter switch, that seems to constantly 'overflow'?

 

http://i89.photobucket.com/albums/k223/altabani/Mobile%20Uploads/20140929_082928_zpsab540a80.jpg

Edited September 29, 201410 yr by Advantage
A quick tidy of the photos.

That should go back to the expansion tank, the overflow comes from the neck if the expansion bottle.

Cheers Wilf, that makes perfect sense, I knew something was a miss here. 

I'm wondering now if this is the cause of the air lock, seeing as that pipe has been dangling down to nowhere, hence creating a hole in the loop and system?

That pipe is intended to help the system bleed itself if air. You will have lost quite a bit of water running that disconnected and not had the system pressurise so thus could be the cause if all your overheating issues

Perfect, thanks. When you take apart a car there is so much to think about when you actually start putting it all back together and you can easily overlook the simple issues. I've ordered some new hose (just because I want new hose), hopefully this will now resolve this overheating and I can start driving the car. Cheers Wilf, much appreciated