Many Turbo owners here have or has at some time experienced the coolant boiling sound when the car has been turned off...
 
many say its a normal occurance while others are of the opinion thats theres air in the system, it got me thinking on the weekend and i decided to do a small test that anyone can do.
Now i have never been a fan of turbo timers until i did this test on the weekend, im still not a fan of turbo timers and till this day have never had one on my MR2
but i have found that the only car imo worth having a turbo timer is the Turbo MR2, as it def stops the boiling sound when turned off if the car is allowed to idle after a decent drive.. ive done some testing and just a normal shutdown will result in coolant boiling and purging sound.. but if the car is idled and you have the heater on full blast for just a minute or so the car never makes the boiling sound.. nothing.. ( the test was done trying to mimic a turbo timer by letting the car idle for around a few minutes and then turning it off)
now im not saying that everyone should get out there and buy a turbo timer ASAP.. but am just curious wethere anyone else has any similar findings, perhaps even someone with a turbo timer thats still gets this boiling sound can maybe try runnign the heater on full blast next time and report the findings
Please feel free to discuss..
 
cheers 
 

I think I read somewhere that the type manifold you have fitted can affect turbos bubbling on shutdown.

Really - i never heard of that before
the above test is on a stock manifold, stock radiator cap, stock cooling system and hiflowed turbo. with a intercooler fan running constatntly. if thats makes any difference.
cheers

I am sure the majority of bubbling issues is due to a cracked heater pipe above the tank.
Radiator stop leak fixed my bubbling for a while then the crack got worse after a year and it started again. I haven't got it back together to say for sure it was this though. I have got the crack resoldered.
My theory is that when the engine is cooling down it draws in cooler water from the heater pipes pulling in air too and the path is pretty easy for the air to travel from the crack to the radiator filler. Maybe my theory is completely crazy haha, what do you guys think?

meh it boils... with the heater or the turbo timer, with a ct26 and stock manifold or the gt30 with custom manifold... it still boils.

i have a turbo timer, and it used to bubble a lot even after idling for a while, but that was when my heater pipe was cracked /leaking. i have  bypassed those lines since then/ tapped into the coolant lines for heating and re bled the system. doesnt bubble anymore even after complete shutdown ryt after a drive, i use the timer nowadays mainly after a good thrashing

The only time Ive had mine boil was when I didnt bleed it probably just before a track day. Bleed it again after woods and never had a problem

Never noticed mine doing it.

TIPSIDUECE, was it very difficult to tap into the coolant lines? Is the heater still as hot as before? Thinking I might do the same and use the heater pipes for my water to air

no not really, it does take longer to heat up but once it does its constantly hot. the americans ussually tapped into the hardlines in the frunk.i replaced alll my hoses with silicone so i tapped mine into the hoses that goes up into the hardlines in the frunk, chopped in the middle and used brass t-piece from bunnings.