What do you think of this - running hot or not?

[tejr]

Past couple of months I'vr had some concerns about my temp gauge reading about 10+'C higher than the ECU readout.

Had Dan Taylor have a quick look one evening and using his infra red thermo he agreed the gauge was reading high. (Actual temps no more than around 85-95 with the dash gauge reading 10'C higher)

Around 3-4weeks ago I got a cooling chip from Joolz just to increase the safety margin in case things ever went wrong but today things possibly took a turn for the worst.

Sat in traffic for no more than a few mins and the needle was bouncing off the 100'C mark (remember this is apparently reading high), got to another light and it starts creeping up to 105, I get the car home 100m down the road and its reading just over 100. Switch off, get my new infra red thermometer out and start taking some readings and the rad end tanks are reading upto 105'C close to the top, the core/cooling fins behind the fans is/are reading 107 and the pipework leading to the block is between 102 and 105!

The fans seem to be cutting in but I've not had a chance to get the laptop out today to see what the ECU is reading and where it think the fans are cutting in (should be 85 and 86 with the cooling chip). Coolant levels were fine

I've got it on Dan Taylors waiting list for a bunch of work, but earliest he could squeeze my in is 20th Dec

Any thoughts/anyone local willing to lend a hand? Will be skipping the tunnel run on Sunday as i have no confidence in the cooling system at the moment Was hugely looking forward to it too, even borrowed the HD video cam from work and had the SLR on charge

[speed8]

If it's actually reading higher than ECU then check the capillary tube from the gauge to the sensor.
When I used to have a Cerb I thought it was overheating till I got the software and saw the same thing, over reading by 10-15C. When I started checking around I found the capillary ran very close to the manifolds. I rerouted it as much as I could and it was pretty much in line with ECU after that.
Just a thought

[Tanguero]

If you are measuring that sort of temp at the radiator or on the water pipe where it comes out of the thermostat, and the software confirms it, then you have a problem.

Other than carefully bleeding the system and ensuring its it properly topped up I don't know what to suggest apart form getting Dan to have a look at it ASAP.

[ridds]

All may not be lost. The engine will ahppily sit at 105 plus for breif periods providing that your cooling system can maintain pressure. Damage occurs when you boil the fluid around the combustion chambers or loose fluid which creates extremely high localised temeratues.

However it would suggest you have an issue somewhere as my cooling chipped car has never gotten that hot. It would suggest a failing radiator or fans or lack of coolant flow (can happen at idle due to poor system and water pump design).

[Allandwf]

I would be checking the small black pipes and the y piece at the rear of the expansion tank. They had collapsed internally on mine . So looked like it had plenty water when actualy it could be quite low. Replaced them and never had any further issues. With cooling anyway ;-)

[tejr]

Thanks guys. Might flush the system tomorrow and put some new coolant in as its needed anyway.

Good point that I've only checked coolant level at the expansion tank, will check via the bleed taps tomorrow.

I thought about bad circulation at idle, but don't think that adds up, I'm thinking at the moment things point to a bad thermostat or sensor really. Once the fans kick in the temp drops quite fast but they seem to switch off again as they should (I guess the ECU think the car has cooled at that point)which is why I'm thinking bad sensor? Anyone know of an equivilent part for the temp sensor I can pick up tomorrow while I change the coolant?

[TDFPELTD]

Allandwf said:

I would be checking the small black pipes and the y piece at the rear of the expansion tank. They had collapsed internally on mine . So looked like it had plenty water when actualy it could be quite low. Replaced them and never had any further issues. With cooling anyway ;-)

Another vote for this, ours ran far hotter that I'd have liked in traffic (105 odd on the gauge and got there quick), sorted this and a few weeping connections, filled and bled and it now sites at 90 when on the move rising to just below 100 on the gauge before the fans come on and drop it back to 92'ish.

[ridds]

I wouldn't bother refilling with coolant until you have fixed the issue. You may reduce the ability of the coolant to reject a little bit more heat but it'll save wasting 5 litres of coolant if you can't catch it!

Another thing to bear in mind is that the coolant temp sensor (ECU) can sometimes cause the fans not to come on. If the connector does not have a 100% connection is can not trigger the fans when the coolant reaches the required temp!! Found out myself when sat in traffic one day, got out, gave it a wiggle and the fans came to life. Very strange behaviour considering that if disconnected the default condition is for the fans to be on permanently.

[tejr]

Got the laptop out yesterday to see what was going on and oddly enough the temperatures matched with what I was reading with the thermometer and at no point went over 90 this time. The fans came on ok (at 85 and 86), and there was a couple degrees drop in temp once the temperature got to around 84-85 (where the thermostat is meant to open if i'm not mistaken) before it began to rise again as normal for a few degrees before cooling again. Need to take it out for a longer run in traffic to see if it'll heat up again and decide not to shed the heat again.

Annoying and dis-heartening, don't really want to use the car tbh. Missed out on the tunnel run this morning cause I just didn't have any confidence in the car