[scenturion]

edit: can a mod fix the title to "Overheating with engine not running after car died on track"

Hey all
I was at Thunderhill on Friday in my NB1 for the first time and was having a blast until near the end of the day, I had a complete loss of power and had to coast over to the side. The engine died and would not restart. I have since found the cause of the failure and fixed it (CKP plate had messed up teeth from a loose bracket), but I'm worried about what happened next.

When I pulled off, the coolant temp gauge was at ~3/4ths. As soon as the car was off, the temp gauge started to spike. It pegged to max and stayed that way for about 5 minutes while I waited for a tow. I could hear the fluid boiling, it sounded like a 'drip drip drip' from the front of the car.
Upon getting into the paddock, there were no obvious signs that the coolant system leaked anywhere. Regardless, I couldnt get the car started at the time and had to get towed home.

I'm concerned that there may have been damage due to the overheating. Its an unusual circumstance in that the engine was not running while the overheating occurred. I'm curious to know what people on CR think, as well as how I should start checking for damage.

I'll update this thread when the car is back together, but advice would be appreciated.

 

[Chewbacca]

You should have turn the heater on full blast...

Have you checked to see if the headgasket was damaged?
The "drip drip" could been from almost anything.
Check for obvious signs of head gasket failure (coolant in the oil...etc..)
If you still cant get the car started I would suggest finding the leak by pressurizing the cooling system. I know the NA miatas have rubber o-ring for the thermo which is made of rubber. Could be leaking.

 

[brontosaurus]

You should have turn the heater on full blast...
.

Wouldn't matter much if at all. With no fluid flow you'd only be removing heat from the heater core and be reliant on conduction to cool the rest of the fluid. If you still had fluid in the system there's a good chance that you shouldn't have any damage.

 

[scenturion]

The car didnt die due to overheating, it died due to a loose bracket grinding away the teeth on the crankshaft position sensor plate (behind the crank pulleys).

If I had to guess I would say the dripping noise was the sound of air bubbles going up through the radiator into the overflow tank.

Anyways, I installed a new plate and the car starts just fine. I then drained the coolant and swapped my radiator for a MSM rad.
When I washed the old radiator out, a bunch of fine aluminum particles came out with it. No idea where they came from, but I guess I need to be vigilant in case the water pump dies suddenly.

The car seems to be okay - no smoke coming out of the exhaust and no coolant leaks that I can tell.
When idling it reaches operating temperature and the fan turns on and off to keep it stable.

I havent yet had a chance to flog it yet, though, so I cant be too certain of it's status.

Also, the brakes feel really spongy now - I wonder if the fluid boiled over since the brakes stopped getting airflow?

 

[kung fu jesus]

How many miles are on this car? Fine aluminum particles aren't unheard of. Your waterpump won't stop suddenly unless it completely seizes. You will generally hear the bearing on it singing and it will then start weeping coolant.

A tracked car needs more vigilant maintenance. Spongy brakes aren't uncommon after a trackday. You should be bleeding them afterwards anyways.

 

[scenturion]

Car only has 34k. I've tracked other cars before and they havent needed bleeding after a single day. I'd really guess that the brakes were hot and didnt adequately cool down.

 

[RedemPhex]

Car only has 34k. I've tracked other cars before and they havent needed bleeding after a single day. I'd really guess that the brakes were hot and didnt adequately cool down.

bleeding brakes after track events is not a car thing. Its a brakes thing.

The suggestion to bleed the brakes after a track event is because brake fluid is inert, the fluid closest to the brakes gets much hotter than the fluid at the master cylinder and breaks down more easily. by bleeding the brakes, you are putting fresh fluid into the calipers.

As for the overheating, I suggest you do two things:
1) do the linear water temp modification to the stock gauge
2) duct your radiator before your next event.

A side suggestion, when going to track events use a 80/20 or similar mixture of water/coolant.

 

[scenturion]

bleeding brakes after track events is not a car thing. Its a brakes thing.

The suggestion to bleed the brakes after a track event is because brake fluid is inert, the fluid closest to the brakes gets much hotter than the fluid at the master cylinder and breaks down more easily. by bleeding the brakes, you are putting fresh fluid into the calipers.

As for the overheating, I suggest you do two things:
1) do the linear water temp modification to the stock gauge
2) duct your radiator before your next event.

A side suggestion, when going to track events use a 80/20 or similar mixture of water/coolant.

Yeah I'll bleed the brakes a bit and take it to an AX this weekend to try and stress test it before heading to THill the week after.

In terms of overheating, I installed the MSM radiator I had sitting around and around 80/20 water/antifreeze with water wetter while I was replacing the CKP disc after the incident. I'll try and duct off the top and bottom when I have time. The linear gauge mod looks great, but I don't know if thats within my level of skill - maybe I can buy a spare and try it out. I would almost prefer to put a themocouple/digital gauge elsewhere and have a small readout in the dash.

 

[memo2nate]

It really sounds to me like a head gasket.... If it is cracked at all between the combustion chamber and a coolant line you will get boiling coolant all the way to the overflow tank. Mine sounded like a drip drop like that.

 

[mdudingleberry]

So its better to have more water than coolant?

 

[RedemPhex]

It really sounds to me like a head gasket.... If it is cracked at all between the combustion chamber and a coolant line you will get boiling coolant all the way to the overflow tank. Mine sounded like a drip drop like that.

what? Anytime you are close to boiling in the radiator will lead to SERIOUS boiling in the overflow. Seems more likely the water just recently spat into overflow tank will boil over anyway than the radiator considering the pressure difference.

And yes, more water=better. Hypothetically speaking coolant increases boiling point, but due to its lower specific heat it boils easier and quicker.

You can do some of your own analysis on this by reading about antifreeze/water mixtures.

Yeah I'll bleed the brakes a bit and take it to an AX this weekend to try and stress test it before heading to THill the week after.

In terms of overheating, I installed the MSM radiator I had sitting around and around 80/20 water/antifreeze with water wetter while I was replacing the CKP disc after the incident. I'll try and duct off the top and bottom when I have time. The linear gauge mod looks great, but I don't know if thats within my level of skill - maybe I can buy a spare and try it out. I would almost prefer to put a themocouple/digital gauge elsewhere and have a small readout in the dash.

Its extremely easy, I did a how-to on it with pictures, but i have not moved the pictures over to a less harassing site. I will very soon though.