D chunk cylinder failure- early signs?

[911Fiddler]

Anybody know what are the early signs, if any of the terrible D chunk failure, ie well before the chunck falls off and the engine mashes up? Eg is it water consumption?

[911Fiddler]

Thanks for the insights baz. Water is clean. No over pressure symptoms but think I will pop on a pressure gauge for interests sake. my coolant loss ( minor ) is probably a weak joint, one out of sight I reckon.

[911Fiddler]

Like that idea, co test on coolant, do I just go to my MOT centre an pop the probe in the open header tank, then Bobs your unc....or not....?

[911Fiddler]

Am now running with a pressure gauge installed on the cooling system so will be checking running values, normal run, high speed/power run etc. Anybody know what pressure values to expect as normal? Am thinking if it says well under the pressure relief value of the reservoir cap, then it's normal?

[911Fiddler]

Some great ideas there! thanks all. Will chase them all up and post the results! P

[911Fiddler]

Baz to extend that discussion does the debate apply to the turbo & gt2, 3 models as well or are these better because their engines are different?

[911Fiddler]

Continuing the early part of this discussion, some data from my science lab (the kitchen).
Investigating the operation of the standard 996 C2 thermostat...

Water...Length of
temp c..thermostat body (mm)

Ambient....65mm
70c........68mm
80c........71mm
90c........73mm
115c.......77mm

She was not in the housing at the time so its hard to assess the actual opening point where flow to the rads starts however for me the most interesting fact here is that the movement is quite small. The total movement from initial opening, say for arguments sake at 83c, through to the cooling fans switch-on at 102c is probably only 5 or 6mm.
I think this adds to the case for fitting the lower temperature thermosatat from Hartech as not only will the running temperature come down (any idea how much Baz?) but additionally the thermostat will have moved more (assuming its got the same temp:mm ratio) and so the thermostat orifice will be wider which means more coolant flow out to the rads -which is what I want.