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Hello Everyone,
My engine is currently being overhauled. It's a IO-320-B1A in a Lancair 320. It was fitted with a remote oil filter and the engine shop has shown me something interesting. They say the wrong gasket was fitted and two diversion valves were installed, with the net effect that oil would not have been diverted to the cooler properly.
Here are some pictures I took and what I recollect of the explanation about the oil system.
In one picture I am holding the oil filter take off housing. The thermostatic valve is in the housing; this extends as it gets hot and closes off a hole in the engine back plate to divert the oil through the cooler. You can see that the gasket cut out does not fit the cut out in the housing; this prevents the valve closing the hole fully. Also, the old fashioned viscosity valve was fitted – in the other picture this is being held in place with a finger. This also prevents the thermostatic valve from extending fully. The viscosity valve was superceded by the thermostatic valve ages ago and you should not have both fitted.
Apparently, the result would have been much reduced flow through the oil cooler.
(With the oil filter on the engine, a different housing is used; the thermostatic valve comes in from a different direction and these issues do not occur.)
I'm told that this remote filter conversion was fitted exactly according to an STC. I have had high oil temperatures with this engine and this looks like the explanation. If anyone has the remote oil filter conversion and is seeing high oil temperatures it may be worth checking these details.
Yours,
Nick Long
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