Need Help with Oil Cooler Plumbing

[WingsOnWheels]

I purchased my engine second hand and it came with fittings installed for the oil cooler that are not in the Vans configuration. I'm trying to figure out what plugs and ports I need to get this all set up. The installation/operation and Overhaul manuals weren't much help.

The current configuration is highlighted in red. As you can see, the banjo fitting is installed above the oil filter. It also came with a fitting installed in the lower "out" port and a plug in the upper "return" port. The manuals describe the port above the filter as being an alternate "out" port to feed the cooler. From what I have read it looks like I need to plug the port above the filter and install a port on the return to the left. That looks like parts 1,2,3, & 4.

Questions:

What is the purpose of the spring and plunger, parts 2 and 3?
It would seem that with the current configuration the oil cooler would be non-op. Is there anything I am missing here or is that top port not a feed port?

Just to note, the engine was torn down and reassembled after it was removed from the A/C, so it is possible that the port config is different that is was installed on the A/C.

[DanH]

Colin, read through this thread:

http://www.vansairforce.com/communit...d.php?t=45548&

Quick answer, no spring or plunger (2 and 3). Install 1 and 4. Install AN-to-NPT fittings in the circled ports

[WingsOnWheels]

Very good, I see that since I have a 90 degree filter adapter with the vernatherm I don't need that relief valve and spring. Thanks for the help!

[Scott Hersha]

You can also keep the plunger and spring and chuck the vernatherm - especially if you have the 90 degree adapter and a spacer. Getting the vernatherm to seat precisely into the seat using the adapter and spacer is difficult. The holes in the spacer are larger than the bolts used to hold it in place, thereby allowing some movement of the spacer on the accessory pad. If you get lucky you'll get it lined up straight and the vernatherm will seat precisely. If you loosen the bolts for some reason, you have to get lucky again. If it doesn't seat squarely, some of the oil will by-pass the cooler because the vernatherm hasn't seated completely. The vernatherm is a temperature and viscosity oil filter by-pass system. It by-passes oil from going through the cooler if it becomes clogged or is cold. The bypass plunger and spring (Lycoming calls it a viscosity by-pass) does essentially the same thing. However, it seats precisely into its milled seat in the accessory case completely shutting off oil by-pass and sending all of it through the cooler after the oil warms up(thinner). It also by-passes in the event of a clogged filter (or anything that increases oil pressure enough to unseat the plunger). When I removed my vernatherm and installed the plunger, my oil temperature dropped 15 degrees on a warm day. I have pictures of my vernatherm that show a wear pattern on 60% of the tapered vernatherm seat and that amount of by-pass caused a 15 degree increase in oil temperature.

[Scott Hersha]

You can also keep the plunger and spring and chuck the vernatherm - especially if you have the 90 degree adapter and a spacer. Getting the vernatherm to seat precisely into the seat using the adapter and spacer is difficult. The holes in the spacer are larger than the bolts used to hold it in place, thereby allowing some movement of the spacer on the accessory pad. If you get lucky you'll get it lined up straight and the vernatherm will seat precisely. If you loosen the bolts for some reason, you have to get lucky again. If it doesn't seat squarely, some of the oil will by-pass the cooler because the vernatherm hasn't seated completely. The vernatherm is a temperature and viscosity oil filter by-pass system. It by-passes oil from going through the cooler if it becomes clogged or is cold. The bypass plunger and spring (Lycoming calls it a viscosity by-pass) does essentially the same thing. However, it seats precisely into its milled seat in the accessory case completely shutting off oil by-pass and sending all of it through the cooler after the oil warms up(thinner). It also by-passes in the event of a clogged filter (or anything that increases oil pressure enough to unseat the plunger). When I removed my vernatherm and installed the plunger, my oil temperature dropped 15 degrees on a warm day. I have pictures of my vernatherm that show a wear pattern on 60% of the tapered vernatherm seat and that amount of by-pass caused a 15 degree increase in oil temperature.

[WingsOnWheels]

That is also very good information. I don't have the spring and plunger, so I will stick with the vernatherm for now and re-evaluate once I am flying.