Cessna 152 oil coolers

[phil0185]

Am I right in saying that the Stewart Warner oil cooler fitted to Cessna 152's is simply a radiator matrix with no temperature controlled bypass valve incorporated?

Any bypassing of the cooler is done by the 'vernatherm' fitted in the accessory housing isn't it?

If this is the case, then the direction of oil flow through the cooler is not important?

 

[AviatorJim]

You are correct in that the cooler will work just as well with oil flow in either direction.
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The hoses specified for the installation should only allow for installation one way (although a lot of people have misrouted the hoses, and have fabricated hoses that allow the incorrect installation. There are also 2 installations of of the cooler that I'm familar with, in addition to an oversize cooler.
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The cooler is not bypassed by the vernatherm. The actual pressurized flow of oil is always within the engine, and when it gets hot, the vernatherm allows oil to circulate through the cooler on its way back to the sump.
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A vernatherm failed open will prevent the oil from reaching operating temp. There is also a high pressure relief that fits into how that system operates.