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Thread: Air bubbles in overflow tank

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2013-03-30 11:24:23
Air bubbles in overflow tank
Hey guys. I recently installed my 90x86mm sleeved motor and noticed something strange. After I drive around for a while and I switch the motor off, a few air bubbles will pop up inside the radiator overflow tank. No bubbling as such, just a few single random bubbles that pop up about 3 seconds apart, and for about 3-5 mins after I switch off, after which it then stops.

Water temps while I drive are between 75deg C and 90deg C.

Funny thing is if I just idle the car to the point that the fans come on and I switch off, there are no bubbles. Only after I drive it around for a while. Also, I'm busy breaking in this motor so I'm only revving up to around 4500 rpm.

I'm re-using the Mazworx gasket. It was n my motor before but it only started up and never drove with it.

Were could the bubbles be coming from? I've bled the system best I could.
Last edited by SR20_Guy on 2013-03-30 at 11-26-54.
2013-03-30 17:51:48
was the head n block resurfaced?.... im hoping its that u didnt resurface the head or the gasket not sealing properly.... dont even wanna say worse case senario.....
2013-03-30 18:40:50
Block yes, head I'm not sure. Someone else built it for me.
2013-03-31 11:41:49
do you have new Rad Cap?
2013-03-31 18:42:45
Head gasket, most likely..... search VVL coolant boiling over or look for on it on the front page in this forum.. theres a video
2013-04-03 04:38:30
If the system is bled and there are bubbles with just driving around, I am sure it will get worse when you start to bring her to 8k-9k. It could be head and block not sealing properly. Uneven head and/or block or bad hg. Or detonation.
2013-04-04 05:58:50

Check the video of the coolant overflow bottle shaking like a junkie. Is yours doing it that bad as well?
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