Most ruthless issue EVER! Coolant...

[MattiasJacobs]

Ok I just spent an hour writing a rant and my iPad died so no more rant, lucky for you guys. My coolant seems to be boiling in my turbo lines and coming up through my upper rad hoseafter shut off. There are no visible leaks, my hg is not done, every heater hose has been replaced, rad cap replaced twice, another coolant change, anal bleeding (LOL!) and this only happens on occasion. Has happened on all 3 motors I've had. My present motor is fully built with 1100km on it. My water temps according to my PFC show 75 or lower while driving and creep up to low to mid 90's after shut off and boiling occurs. Any other heat soak will usually stay under 85, unless the boiling happens. It doesn't boil in my reservoir and the thing has never over heated. My cooling set up is an N1 water pump, Godspeed rad, 76.5 thermostat, stock clutch fan, and 0.9 rad cap. Now I need to figure this problem out before I go insane and pull the motor to ditch everything I should've in the first place. Aka heater core and stock oil cooler to at least make less of a chance for leaks. Is my thermostat too high to keep up with my cooling system? Could my heater core be leaking? Or is the water now just sitting in the turbo and boiling because it's not flowing? Do i worry if its option 3? I don't lose coolant so I'm effin mind boggled. I've done every possible thing to avoid this and it still happens. Note i thought i solved this issue until i didnt time my car out today for curiousity; usually 4 minutes. Please enlighten me. Too much invested to give up now...

[G-Rock]

Why do you think it's boiling? Specifically in your turbo lines? Especially to only happen occasionally. Have you tried pressure testing your coolant system when it's hot, and cold?

[caliber676]

If your car is hovering around 90c that seems to be a pretty normal temperature from my experience. And if it's not overheating then even less concern. But if you figure your coolant is boiling then one can assume air is being introduced into the system. I would suggest you attach a coolant system pressure tester and leave it over night with the pressure applied. Come back and see if the pressure drops and if it does you have a leak. I would definitely check your heater core if your running out of places to look

[G-Rock]

I agree with caliber, just take note that if you throw a pressure tester on your car when it's warm and let it sit overnight it will lose some pressure because of the temp dropping. So try and pressure test it cold, should stay fairly level then.

[MattiasJacobs]

Thanks for pointers. I pressure tested it for a few hours prior to taking it in for tuning but nothing as long as overnight. You can feel bubbling when you grab the upper rad hose. Or maybe I have lost my mind. I wait and check almost 9/10 times I drive my car.

[G-Rock]

You may be losing your mind =D If the car isn't overheating then you don't have any air pockets in your system. Also if your not having to add coolant then you aren't displacing air anywhere either. Just make sure your overflow is topped up accordingly and drive it.

[MattiasJacobs]

Pressure test will commence tomorrow. I have to hunt down an igniter pack anyway, I was stupid enough to sell an extra one.

[BRN32]

Convection can keep coolant circulating after shut down, this could be what your noticing.

[vonzipper]

Had this same problem with my car,bubbling sound after shut down,not loosing any coolant. Its air trapped in the cooling system. To get rid of it, jack the front of the car up take off the rad cap and run the engine to operating temp with the heater full hot. this will burp the system of any trapped air. Replace the rad cap and that should do it.

[GTRADDICT]

What vonzipper said... But it sooo sounds like a HG! Even if you said it's not. Could do a compression test to be sure.

[MattiasJacobs]

I've done a comp test and burped the system hard core, maybe I should do it again. Don't forget this is a brand new motor. I've had a blown hg on an Rb before, so I really really doubt it is that.

[speedfreak]

You mention pfc so I'm gonna guess there's been some map changes.
What are your AFRs like at idle/boost and cruise, are you having misfires at idle when the coils get hot.
Do you have O2 feedback and O2 reg turned off?
Basic question is are you sure your coolant mixture is the right % for the brand you used.
Is your rad plugged internally.
Base timing is proper?
New engines produce more heat as break in goes on

[MattiasJacobs]

My trust was put into the hands of radek, I didn't even start the new motor myself. Only problem with my coils are they started crappin out once in a while on full boost. Only after my comp test tho which pisses me off. But I doubt its coils because I've swapped in both very new oem and splitfires no improvement. So I'm purchasing a new igniter pack hopefully solves it. Also I used the highest protection from boiling according to the back of the coolant. Mix is 60% coolant 40% distilled water.

[bobbo]

Did you use the bleeder hole on the top of the motor?

[DarkCaporaL]

If there was a leak you'd see the coolant level go down and/or you'd see some coolant on the ground. If air goes in coolant has to come out somewhere.

I started noticing that same noise last year and I went through everything you are going through.

Completely changed the coolant, bled the system, checks for leaks, etc and everything came back fine. No overheating either. Only does it sometimes and seems to only happen on those super hot days or when I push it a bit.

Never had any issues, car runs great. Alot of people get the same thing but don't even notice it, because you essentially have to open your hood when you shut if off to notice it.

Read a multitude of threads on the internet and it would seem it's normal and it's not actual bubbling, but it's the coolant moving back from the turbo lines through normal convection.