Running very hot Mk1

[bertiedee]

Last night, on the way home the temp gauge shot up towards towards max. Eventually the cooling fan cut in and after turning on the heater to full heat, the temp gauge started to drop back to normal. When it had cooled, it took about a litre of coolant to bring the level to full. I ran it for 15 mins this morning and the temp was fine, but as soon as I hit the first traffic it started to rise up again to max level. (I am in Cumbria so the traffic is never too bad). I didn't want to take any chances, so its in at my local mechanics to look at, probably tomorrow. Any ideas? Is the Head Gasket the most likely cause . Had the car (V-Spec Mk1 1600)almost 10 years now and never had any problems. Usual maintanence over that time, including cambelt and waterpump 3 years ago.

Thanks

[MonkeyDust]

My money would be on the radiator, thermostat stuck shut is another possibility. Check under the oil filler cap and dipstick, look for loads of mayo like stuff. No mayo and the head gasket is fine, and if it had gone I'd expect more than a litre to be lost.

[Benrad]

I'm guessing the fan did nothing but the heater was what brought temp down? In which case it's thermostat, £30 for OEM replacement and with a jack and stands (possible without) and a socket set it's take maybe an hour to fix.

Could be radiator but unlikely to suddenly rear its head in that case...

[MX-5 Lazza]

95% radiator. The gauges don't tell the truth i.e. they aren't calibrated to show the temperature. They pretty much show cold, warming, operating temp, overheating and fatal. It might have been getting close overheating for some time without the gauge giving any clue.

[Digby]

Could be a combination of all sorts.When my old car was messing about temp wise, it turned out to be rad, rad cap, thermostat and a tiny split in a water hose.

We only discovered the hose was split when a friend revved it as I looked under the bonnet and saw a jet the size of a cobweb strand squirt out.Up until then, I had no idea where the coolant was going as it wasn't enough to make things wet and not enough to leave traces on the ground.I replaced all the hoses in the end and it was perfect after that.

I also had the well known expansion tank gurgle before I changed those parts.

[bertiedee]

Thanks for your helpful replies.
Garage managed to look at it yesterday afternoon and I picked it up 1st thing. Apparently there is a rubber/plastic blanking plate at the back of the manifold which had perished and was the cause of the coolant loss. Everything else fine, and had a great run in the sun to work through the lakes. £67 all in to put right so very happy and relieved.

[VladD]

Great news.