This oil cooler thread has been very interesting. Many issues with cooling appear to be according to setup and how the aircraft performs in weather temp extremes.
Yes I agree that masking over the cooler does work if you have a standard setup but remember that the oil has no choice but to flow through the cooler when fitted with the Jabiru OCA (doughnut). In cold weather the oil flow may be partially restricted due to the viscosity and will struggle to get to the ideal temp range of 85C-95C, If oil pressure is high due to slower flow then it is very possible the relief valve can open dumping oil back to the sump and bypassing the bearings. Oil viscosity is clearly demonstrated in my engine by the dropping oil pressure as it approaches 90C+. Oil pressure is only genereated by the resistance of the oil as it flows to the parts in the engine, bit like putting your thumb over a hose pipe, thumb off = no pressure but full flow, thumb on = high pressure but lower flow, a lot of concern is raised about low pressures but as long as the flow is there then perhaps it is not as bad as thought, the down side with low pressure is it may not flow to the furthest away parts in the engine.
With a TOCA fitted the cooler is bypassed until the oil gets to a working temp, this results in a faster warm up time. In cold weather unless the oil reaches at least 85C+ then the TOCA sensor valve will remain closed and no oil will be diverted to the cooler.
The actual true oil pressure going to the important parts of the engine can only be measured when the pressure sensor is fitted to the 'gallery port'.
With the sensor fitted to the standard port a possible worse case senario is to have a completely blocked cooler circuit (kinked oil hose), a normal pressure reading on the gauge will be seen and no pressure in the 'gallery' leading to dire results. This is why I advise if doing work on the oil system to consider moving the sensor to the gallery or adding a second gauge for comparison. I did this during the testing phase and was surprised at the difference between the two ports, another reason I recommend AN8 hoses.
I am having another batch of TOCAs made and should be ready in a few weeks, I plan to be at Sun & Fun in April if all goes well and intend bring a few TOCAs with me just in case anybody going want to see/purchase with price saving.
For more info email
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Steve