Art,

 

If the vernatherm seat is not smooth, the oil will bypass the cooling fins and return to the engine.  Interestingly, TCM says that 2/3 contact is adequate but I don't believe it.  If you remove the vernatherm you can see the wear pattern on the end and see if you have 360 degree contact.  Lycoming actually has an SB and a tool for reworking the vernatherm seat but I've never been able to locate the SB or the tool.  TCM recommended milling down the vernatherm washer to about half its thickness to seat the vernatherm a little deeper and, in theory, close it earlier and maybe a little tighter but I don't know of anybody who's tried to do that.

 

TCM's willingness to work on the problem is minimal, exchanged coolers have been sent out, but no real answers.  I worked with another ES guy who was running hot and got an exchange cooler from TCM.  We sent the hot running cooler to a testing lab and had it performance tested (as a favor) but never got the results back.  Now that this discussion is happening again, I'll try to contact the engineer.

 

If I were to replace my cooler, I'd contact Pacific Oil Cooler and order a "G" cooler, TCM part# 654580, Aero-Classics part# 4000440.  They've already told me they would accept an "N" cooler for the core.  Much cheaper, and in my opinion better made, than the factory cooler.

 

Yes, Karen and I are heading for Fredericksburg, not sure what day, probably Thursday.