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Coolant in combustion chamber

Started by _Viper_ , Jan 29 2012 03:39 PM

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6 replies to this topic

#1 _Viper_

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Posted 29 January 2012 - 03:39 PM

Hey guys, I took my lil Gemini to Motorvation couple weeks ago. Motor was on its way out.. Im actually impressed it survived another year.

On the first day my thermo fan failed while stuck in traffic and it got to about 115-120'c Fixed the thermo, let it cool down and it seemed to run fine. After abit I noticed it was only running on 3cyl's.... Pulled the spark plugs and #4 was green and fouled with coolant

Since it was a $300 wrecker motor and my new one is just about ready I slapped in a new plug and enjoyed the weekend

Anyway this weekend I thought id investigate. Pulled the rocker cover and there was a small amount of coolant around the rear of the head... not much about 3-4 drops worth.

Pulled the head, #4 combustion chamber was speckled green. Head gasket looked fine, no signs of damage, no corrosion on the head and is not warped. but the intake port was coated in green coolant also

Soooo Im thinking the head has cracked somewhere in the intake port? possible in the valve stem seal bore which would explain coolant in the intake and a little under the rocker cover?

Would that be the most likely cause?

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#2 _Gunmetal LH_

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Posted 29 January 2012 - 05:22 PM

I'd say it got too hot, warped or cracked something.

If it got to 120degC then the coolant would've been boiling (creating steam which doesn't take away sweetFA heat) and I reckon the alloy head would've overheated.

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#3 _stretchlc_

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Posted 29 January 2012 - 05:57 PM

Is this a G series engine or one of the 4Z series?

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#4 _Viper_

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Posted 29 January 2012 - 10:31 PM

4Z, with a D1 head which are known to be prone to cracking.

Im just interested on the diagnosis just to learn... I thought it was funny to have coolant in the intake port before the valve.

Is it common for heads to crack inside the valve guide bores?

Edited by Viper, 29 January 2012 - 10:33 PM.

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#5 rodomo

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Posted 29 January 2012 - 11:05 PM

Does the inlet manifold have coolant running through it?

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#6 _Viper_

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Posted 29 January 2012 - 11:47 PM

Nah, and there was no coolant in the intake manifold... it like it stopped dead where the intake bolts onto the head :S

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#7 UCgazman

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Posted 30 January 2012 - 12:29 AM

My brother just replaced the head on his Rodeo, it was cracked right down the middle. We looked at heaps of 2nd hand ones and they were all cracked or welded up, so he ended up forking out for a new one. Seems like a common fault for the 4Z...