Check this bad boy out!

[Apache]

Surely cavitation is only likely in the pump? Why would it happen in the head cooling channels?

[MWS]

Interesting question, a generator engineer friend of mine has mentioned cavitation causing some failures in some of his engines,but I can't remember if it was cylinder heads or cylinder bores.He said on his older engines he liked to run demin water/glycol only,and with more glycol than reqd.ie if it needed 50/50 he would run 30 demin water 70 glycol.

Isn't cavitation usually a pitting, or erosion found on items such as maritime propellers, or the vanes on water pumps (something to do with the dynamics of the "swirl" characteristics) ? .....I spoke to someone, some time ago, who suggested that a lot of "grey imports " got cracked heads due to the change in the quality of the fuel when they come here. our fuel being a higher octane, and producing higher combustion temperatures..........Maybe someone with more knowlege than I, could comment................

[shokenore]

Surely cavitation is only likely in the pump? Why would it happen in the head cooling channels?

In my VERY limited knowledge of water dynamics , I would agree with you with regards to the pump,I have seen pump blades pitted and broken due to water cavitation,and have seldom had the chance to look down/inside cooling chambers on a cylinder head.
But I think demin water would still be better than malvern spring water.

[s car go]

I spoke to someone, some time ago, who suggested that a lot of "grey imports " got cracked heads due to the change in the quality of the fuel when they come here. our fuel being a higher octane, and producing higher combustion temperatures..........Maybe someone with more knowlege than I, could comment................

Possible,but I've had two heads crack,one on a 2.4 Hi-ace and this 4 Runner,obviously neither of them ever run on Japanese fuel.

Incidently,my head suffured virtually an identical crack,IE between the valve and swirl chamber,but pot 3 IIRC.