1990 Mazda Miata MX5 - Disco disaster - MX5 progress

Funnily enough the Aston picture was err taken by me!

It was fun but also frustrating as it shows up things I want to improve, mainly my driving ability.

Look forward to it! I have an Audi Quattro to do. Where did you source different wheels from?

Decided to use the Mazda for a short journey today, scraped the ice of both sides of the windscreen, heater on full etc. I'd used it last night in the cold with no problems. Driving along road and lots of steam coming from front right of bonnet/ pop-up light and temp gauge at top of scale, whoops... Pulled over, shut down and bonnet up, hose from top of radiator to expansion bottle had popped off and lots of steam from radiator. Let it all cool down and nurse it home stopping a few times for it to cool down. Last time I stopped as it was cooling down there were some interesting noises, like something popping back into shape, and when I then drove the remaining distance home the temp stayed constant.

I was probably a bit stupid trying to use it in this weather as I've always been a bit suspicious of the cooling system and don't know what the anti-freeze situation is. Maybe there was a blockage that cleared during the last cooling down period? I have noticed in the past that the top hose has compressed (squeezed in). Hopefully I haven't caused any real damage the engine is still running fine so hopefully the HG is OK.

When the weather is kinder I will flush the cooling system out refill with ant-freeze and bleed it. The car has had cooling issues in the past, see early posts, but I had the thermostat housing changed, a new water pump and some heater hoses at the same time.

Sorry too many words and no picture as I was too concerned to get my phone out, it did look pretty dramatic though. First time it's let me down though (not counting dodgy battery issues).

Mark

p.s. With respect to de-misting ability will removing the A/C bits and pieces improve things?

The HG on these is very easy to do.
I'd guess it was frozen also, you'll soon know when you refill with proper AF and run it up to temp. You sure the noise you heard was not bubbling in the radiator etc, these engines are fairly bullet proof so you may have got away with it. Demisting the screen works better with the AC on and it set to screen, unless you are wanting to reduce weight I's keep the A/C also they come in handy if you Supercharge ;-)

You mean under the dash? The big white box under there is pretty restrictive in terms of airflow - I definitely noticed a difference changing it for the regular pipe. It's a easy job to do, although make sure you have a hoover on hand because it'll be full of pollen.

Sounds like an airlock to me. Run it to temp with the rad cap off until it bubbles out. Should be OK.

I use mine in all weathers, I think it's the oldest UK car on the road. I did a massive resto on it last year. Thread here if you're interested: www.motorpunk.co.uk/articles/total-restoration-of-one-of-the-oldest-mx-5s-around/

Might have been an airlock,but given the temps the last couple of nights some freezing in the system is a fair bet.
You can get a cheap antifreeze tester from Halfords for a couple of quid,well worth having.

I changed the coolant on mine last September,there was a really strong mix and loads of coolant in the expansion tank and curse word all in the rest.The previous owner must have thought you just filled the expansion tank when topping up! I only got 2 litres out of the drain plug.

Easy job but the plastic drain plugs have a crosshead screwdriver fitting which can get a bit chewed up,cheap to replace though.
Also use the old style blue antifreeze not the pink OAT stuff.Apparently the pink has been known to cause issues in the system due to yellow metals (copper) in the heater matrix.

Collapsed hose,may be internally restricted even if it looks ok in the second pic.Could well be a faulty rad cap causing a vacuum.

The system should hold about 6 litres all in from empty.

I raise the front of the car up a bit and set the heater to full on as its helps stop airlocks,then fill the rad and then the expansion tank.
Run it up to temp with the rad cap off and give the hoses a squeeze to help dispel any air.The level in the rad should drop a bit as the air bubbles out so keep topping up as you do this.

Once it's all settled down and the level seems to be stable switch off and let it cool down fully.Once cold go back and check the rad level again,top up if needed and job done.

It looks pretty mucky so not a bad idea to flush it with the thermostat out.