Hi,

I was driving my Fd yesterday and the coolant fill up light came on after 20 minutes and the buzzing started after 20 mins of driving, it then went away after 1 minute the temp gauge didn't move i shortly after stopped the car.

I then started the car again about 30 mins later and it started buzzing again and then the temp gauge started to heat up, my ecu has a limp mode programmed at 108c that kicked in, I then pulled over and coolant was leaking out of what i presume to be the overfill tank, there was coolant dripping off the oil lines below the tank.

I let it sit for an hour and poured some distilled water into the AST tank which sits higher than the filler neck, the AST wouldn't accept much, probably 300ml. I drove home no issues.

Today I put some more water in the filler neck because the Ast tank was still relatively full.
Drove 40 mins no issue.
Stopped the car for half an hour and started it again, fill up light and buzzer went off, i looked at the over flow tank it was high?
Turned the car off for a little while then it had no issues again?
After leaving the car for 2 hours the overflow tanks level went back below half way.

Now my radiator is aftermarket and has no filler on it. So I have been putting small amounts of water (100ml) in the filler neck because thats the only area water levels are decreasing.

Sorry for the long post.

Elliot

 

99% chance your coolant seals are going or gone. 1% chance it is a bad fill cap or AST cap. Basically your coolant system is being overpressurized by exhaust pressure, forcing coolant out the overflow tank.

This is a very common issue with these cars, so common that the buzzer is known as the "change engine buzzer".

You MIGHT be able to gain yourself some time by using one of the various 'block sealer' products. I did, several years ago...gained about 10,000 miles of use before it was done. The key is in preparation, follow the instructions to the letter. The BITCH of it is...you have to drain ALL the ethylene glycol coolant out of your system. I mean like, ALL of it. Then do the treatment, and if you want to run antifreeze/coolant mix again, you have to drain all of the sealer out of the engine, flush and flush and flush and FLUSH it before you add ethylene glycol back in. You risk plugging up things you don't want plugged up if you don't follow the instructions.

Good luck!

P.S., go ahead and change both pressure caps out FIRST, as that is a relatively cheap test.

 

Damn, I was hoping this wouldn't be the case, I have only put 600km on it since buying it.
Well it was only a matter of time.

I plan on tracking the car, if I did the band aid fix would this work with the abuse ?

 

Better off rebuilding it sooner than later because coolant leaking into the combustion chamber will eventually cause corrosion. Continuously overheating will warp the rotor housings and they will not be reusable. Also when the seal finally lets go, it usually is catastrophic and will leave you stranded.

 

As IRPerformance mentioned, delaying will end up costing you. It will corrode/pit/rust the coolant seal grooves and make the inevitable rebuild a lot more expensive sourcing irons... and possibly housings.

 

I just completed a compression test on the cooling system, couldn't find any leaks... Last hope I will be replacing the caps tomorrow.

If there is no result, I will send her next week for a rebuild. Pretty upsetting not even 1 track day since buying it, barely 1000kms

 

Sounds like my recent experience.. It was like you explained
I checked for coolant in the combustion chamber by removing the spark plugs and felt with my finger and used a napkin for soak up any would be fluids. Turned up dry, so i was puzzled.

Until one day a ton of white smoke consumed the traffic behind me.

Turns out it was the coolant seals in my stock twin-turbos, THANK THE ROTARY GODS RIGHT?! anything but the motor, phew..

Before you start dishing out cash, or pouring stuff into your coolant.
stop driving your RX-7 and take your time dissecting the symptoms. Let it idle, stare at the exhaust, smell it, put a napkin to catch any liquids ejecting from the rear.
Hope the best for you.