Overheated today :(

stevo2, Feb 8, 4:49pm
Today we took the MX5 for a run down the line and after about 100km the temp gauge started climbing rapidly. It was another 400mt before I could safely pull over. The gauge was as far over as it will go.
The radiator cap was just sitting there, not tightened down. I can only assume that maybe I hadn't tightened it when checking fluids before heading off this morning.
After allowing it to cool a bit I emptied our water bottles and thermos into it while idling and the temp dropped back to normal.
We topped it up at the next town.
We finished our journey, approx another 150km with no problems at all, the temp gauge sat at normal.
We are off to Napier in a couple of weeks and I want to have it checked out for any damage that may have occurred before we go.
If I took it to my mechanic, would he do a TeeKay test or something else?
98 MX5 1600cc just under 100,000km
Cheers Stevo
msigg, Feb 8, 5:02pm
Yes get a teekay done, chances are since you were on to it that it will be OK. If the next day it idles alright and runs good, check the water for lots of big bubbles( small bubble nothing), check oil, Yea should be fine.
Are you going to the art Deco weekend.
thejazzpianoma, Feb 8, 5:02pm
Don't forget to put fresh coolant in as yours will likely be far too dilute now which is not a good thing from a corrosion protection point of view, can actually be worse than just running plain water. I would flush and go for fresh mixed with de-mineralised water.

If the thermostat for those isn't expensive I would also replace that while I was on the go as they don't tend to like being overheated.

Aside from watching for water consumption, "milky" white under the oil filler cap, steam from the exhaust, over pressurisation and bubbles. Another surprisingly good "at home" test is to pull the dip stick and drop a drop or two of the oil on to a really hot surface (tinfoil on the BBQ or whatever). If it "sizzles" (and this is obvious when you see it) there is water in the oil.

Other than that a mechanic can do a tee kay test and pressure test the system.
gsimpson, Feb 8, 5:05pm
You should be OK. The water boiling (this absorbs the heat) and you stopping promptly should have saved the motor.
robotnik, Feb 8, 5:17pm
I'd buy a Teekay tester kit (or the Repco branded one which is cheaper but has less tester fluid) from Repco and do the test myself. It is a useful piece of kit to have around actually.
stevo2, Feb 8, 5:32pm
Yes msigg. We are off to the Art Deco weekend. Will phone my mechanic tomorrow and sort a Teekay test as I wont be taking over those hills without it being checked out.
msigg, Feb 8, 6:11pm
Yes best sort it,I will be towing a car on trailer down from Auckland, I have been down for the last 7 years. Great weekend.
henderson_guy, Feb 9, 11:55am
So if you're not supposed to use tap water, why does my late model machine which is worth much more than your average car and runs a Japanese turbo diesel specify to use tap water in the service manual?
bigfatmat1, Feb 9, 12:22pm
High iron content can cause issues. I have seen one particular make of new vehicle where heater cores have leaked due to tap water with high iron content Being used in them
gsimpson, Feb 9, 3:54pm
Watch out for our little blue 1946 Austin 8. Back on the road after 28 years in storage. Driving from Oamaru! Did Art deco for first time last year and saw the trust's Austin 16 so motivated me to get Austin 8 ready for this year.
jordie9, Feb 9, 5:36pm
What are Toyota Mark X cars like?
stevo2, Feb 14, 12:00pm
So the test has been done and the overheat has done no damage. Pressure tested for over 30 minutes.
The radiator cap has been replaced as it is thought that may have come undone.
Goes like a rocket again :)
clark20, Jun 18, 7:53am
Great, it sounded like you were on it quickly so no real damage would be done.