Ok Ill try to put this description together as well as I can.

I noticed in the colder weather it runs a little hotter, around 88 deg (on PSI3). Never overheats on boost, but when driving a bit slower the temp can go up to 97-98 deg and then the fans will kick in and bring it back down to 84-88 deg. I understand this as normal operation.
Now the weird part. On the very odd occasion it will sit ticking over after a drive, and can heat up to 103 without the fans kicking in. I did notice tonight the fans kicked in and the temp didnt drop at any rate, popped the bonnet and the air felt cold blowing off the fans and round the engine area (usually a bit of heat being blown off the block). Stop then start again and the good condition returns.
Stopped after that and the heater was blowing cold. Stopped the engine, came back and everything, heater, running temps back to normal.
Any ideas? Im wondering if the thermostat is on its way out, given the intermittent nature of the issue.

 

could be the ECT and giving the ecu/psi3 weird readings ?

 

ECT? (sorry!)

 

"engine coolant temperature" sensor

 

Green Army I want your PSI3!!!

 

That PSI3 is going nowhere I'm afraid (unless I break the car due to HG!) it is such a godsend. The temp gauge is so hit and miss in the cluster, the PSI3 says 103 deg and the gauge hasn't even moved.
Any other theories about the above? ECT sound the likely issue, does it have any bearing on when fans kick in?

 

The ecu temp sensor may be acting up and giving false readings as the one on the dash uses a different sensor

 

Not exactly true, it uses a different connection on the same 3 pinned sensor on a Bugeye.

Pin 3 connects to temp gauge, Pin 2 to ECU, Pin1 to earth.................

 

Interesting, but a change of sensor would prove/disprove the theory. Bit of a slapdash way of operating I know, but worth a punt.
I dread to ask, but does any of it sound like HG?

 

Ah right , sorry thought was the same as classic

 

you could get a infra red thermometer and compare readings, the 103 etc is what makes me think it may be the sensor, if your car was hitting high temps and using water then it may be a HG.

 

Sorted. I had a look-see at the coolant level this weekend, and as I was about to pop the header tank lid I noticed pink residue on the hose from block to top of rad. On the exit from rad to block (bottom hose) was more of the same. I guess the hoses are on their way. In any case, I checked the coolant level and it was a little low, so I carried out the top up and bleed air process. This has now removed all the issues listed above. The car had just been driven, and I am watching the temperature remain at 88-89 deg. No 90s!
With all this in mind, I plan to change the coolant and rad hoses, would it be worth changing the thermostat as well?

 

Change the thermostat whilst you've got the hoses off, Alyn at AS Performance is probably your best bet price wise for a genuine one locally. Dennis Common's in Longframlington is closer to you though, Myles.

 

Thanks Micky, bloody little costs here and there are great!

 

It all adds up.

My car overheated a couple of years back, enough to deform the early plastic header tank, swapped the thermostat and it's been all good ever since.

They don't come with gaskets for the thermostat housing, a smear of instant gasket around it does the trick.

Don't envy you doing it this time of year though. It's much colder up here, as you're probably finding.

 

Yes, I need to do an oil change also, before new year preferably. The cold keeps you switched on though!