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High engine temperature.


New Gloucester, Maine
We had an oil filter adapter added to our pa-18 o-320
The temperature on gage today was 250 or so way higher than before the oil filter adapter.
mechanic will work on it tomorrow. Could be bad sending unit
the sender got relocated onto the oil filter adapter.
Is there a temperature valve that opens & sends oil to the oil cooler? If so is that apt to fail & is it easy to replace? Any advice to solve our problems would be appreciated.


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There was some problems with early Tempest oil filters not having enough holes in the base restricting the flow through the filter. They have corrected this problem as the newer filters have more flow. You either have an oil viscosity valve a piston and spring located on the top of the accessory case by the oil cooler fitting. These can get worn or stick not allowing oil to flow through the cooler. The other oil cooler control is a Venatherm that can be installed into the oil filter adapter. It uses temperature to regulate the flow of oil to the cooler. Its like a neeedle and seat and the seat can get worn on the accessory case. You do not want to have both types installed. Only the viscosity valve or the vernaatherm.
Also make sure the gasket that came with the filter adapter is installed. It is different than the standard Lycoming gasket.
Cliff, yes, the Vernatherm (oil temperature thermostat) is a common part and when installing a spin-on adapter, it goes into the adapter housing just below the temp sensor. IF your engine uses a viscosity valve the Vernatherm port should be plugged. Casper Labs and B&C sell that plug if you need it. You should not have a Vernatherm in the adapter if you didn’t have one before the adapter.

B&C and Casper adapter gaskets are not the same. Make sure your mechanic installed the proper gasket, or if he made one, make sure he cut the small flow port holes to match the adapter base.