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DaveL
02-13-2012, 11:17 AM
About a month ago I found a slight coolant leak was apparent. Not the "cursed plug" at the rear of the head because it doesn't exist anymore.
Searched all over for about a month, no smell, no coolant in the cabin, and a compression test was good, i.e. no bubbles in the radiator and good numbers. Turns out it was a pin hole in the "T" coming off the thermostat neck. Got a replacement from Panicmotorsports and started the swap.
What a PITA that was, remove cam cover, front cover, water pump drive pulley, cam gears, plate behind the gears and finally the neck itself
where it now resides in a neighboring county after I hurdle the SOB.
Put everything back together and after 3 1/2 hours and a 100 mile, drive all appears well.
Just thought I would post my find in the event it may save others some grief.

chavy
02-14-2012, 04:24 PM
i had a similar situation but my pin hole leak was on the coolant bypass pipe (the one by the header). luckily it was right by the hose so i pushed back the hose to cover it. i'll prolly replace the pipe when it's wp/tb time again

DaveL
02-15-2012, 09:58 AM
I was hoping to do the same, but mine was almost at the joint. No luck using the hose to cover that.

kung fu jesus
02-15-2012, 11:10 AM
stuff like that is why I am adamant about changing hoses and seals when doing the TB maintenance.

MX595
07-08-2014, 10:12 PM
I too have a mystery coolant leak, no overheating, but coolant resorvior was basically empty, and it appears as if the coolant leaked towards the rear of the engine, and down the back, I recently did the TB/WP and recommended seals, this post was very useful, and I will also check out "T" coming of the thermostat neck, any other ideas considering where the leak is? Thanks

kung fu jesus
07-09-2014, 07:26 AM
The rear of your engine, the heater hoses, water temp sensor, and the cap they plug into are the main culprits for a coolant leak on the back of the engine. Is it on the left or right side?

Rogue
07-09-2014, 07:37 AM
12055

kung fu jesus
07-09-2014, 08:05 AM
Ugh...another tool I HAVE to buy. :p

RuckkehrMiata
07-09-2014, 08:22 AM
My last miata had a "steam" leak coming out of the heater core hoses. The pipe was just barely dinged (my heater core was second hand) and shaped sort of like a pacman type dent in on the circumference.
It only lost coolant once the car was hot, and even at that it took like 2 weeks for it to lose an appreciable amount....


Well thats not entirely true, the radiator also had a hole in it so I threw a mishimoto in and the reservoir had hairline fractures in it from heat and age.
But the weird steam leak stuck around after.