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2G Coolant boil over/bubbles from radiator filler cap

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954g63gst

10+ Year Contributor
219
21
May 24, 2012
gardner, Massachusetts
So I switched from stock fans to Mitsumoto and found out they draw more amps on the relay, the hard way So fans don’t turn on at the moment. I ordered a chase bay duel fan relay kit. But my main question is are these bubbles normal or from the video/pic can you identify a possible area to diagnose? I get a pencil eraser size bubble every 5 seconds for 15 min could be longer but car overheats do to fuses blowing and fans not turning on
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I would check for a leaking head gasket. Your description fits the issue.
 
So trying to fix a Mitsumoto slim fan not powering caused my coolant to empty out of the overflow. So I’ve been adding new coolant and I can’t get this bubble to stop reappearing. I think air is getting in threw the turbo if that’s possible is there a test? Boost leak test with cap off? Or any other suggestions?

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Use a radiator pressure tester and see if it holds psi. If not you'll either see a visible leak somewhere, maybe inside the car, heater core? Or, if you can't find a leak then it might be head gasket. You should be able to pump it to pressure, and use a spray water bottle with dish soap and spray all cooling lines (throttle body, heater core, turbo) and if there is a leak you should get bubbles.
 
It's possible to have a very minor leak in the head gasket where combustion pressure is forced into the cooling passages but little to no coolant gets into the chambers. Agree with both leakdown and boost leak tests.
 
I believe you are correct on this one. Would also explain the spark plugs looking like they do. Does the car smoke while at idle?
Yes white smoke at idle. but it’s very cold where I live. It doesn’t smell sweet. And it goes away after 5-10 mins.
 
Probably standard condensation and not coolant leak then...

Any chance you have an air pocket in the system that is gradually resolving (hence the periodic bubbles)?
 
Probably standard condensation and not coolant leak then...

Any chance you have an air pocket in the system that is gradually resolving (hence the periodic bubbles)?
Many Mitsubishi engines require unusual procedures -- i.e., not just 'open cock ... wait ... close cock ... pour in coolant & done' to change coolant. I'm pretty sure the 4g63T is among them. If you've changed (or done anything that dumped some) coolant and refilled lately and the fussy procedure wasn't followed an air pocket is likely.

I believe other (non-shop manual) ways to fully fill our engines have been mentioned here recently. But I don't remember where.
 
When i did my BLT with a suspected blown HG i could hear was sounded like boiling water in the distance its very noticeable. My gasket compression blew long before it got to the exterior. The bubbly noise could be heard better when the engine was room temp.
 
If you were leaking combustion gasses into the cooling system, you'd smell gas in your overflow bottle. You may also have oil slicks in your coolant.
 
Coolant appears to be very clean. but I have a Mitsumoto coolant pressure tester being shipped to me to test the system and till then I can’t do much.
My radiator is out of the car I’ll pressure test that separately then install it.
I took my TB off to redo the seals and install thermal gaskets along with the intake manifold.
My injector # 3 leaked bad on boost test as well so I got a new seal kit.
I blocked off the FAIV on the TB.
Once I test the radiator I’ll reinstall everything and pressure test the whole system.
 
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