Lycoming oil cooler line connection
 

I found an image on the forum that showed the accessory case of a Lycoming engine with specific locations for connecting the oil cooler lines. My engine is an IO-360-A1A and I'm having trouble removing the plug that is located at one of the locations so that I can install the appropriate AN fitting. My question is (referring to the file linked to below) if it would be acceptable to use the #2 opening (located behind the tach drive--there's a plug sitting on top of the opening) rather than the #1 opening (which was identified in the other diagram)? It appears to me that both openings are in the same oil passageway in the back of the accessory case. Thank you!
https://drive.google.com/open?id=1zr...J7Jntb61LCzvfv

Assuming you will be using a vernatherm, yes you can use #2 as you cooler output. 1 and 2 terminate the oil pump feed channel. However, #2 is a straight thread opening and it looks like an NPT fitting is in there in your picture. You'll need to investigate that. I ahve seen replacement caps that have an AN flare fitting on them to do exactly what you are asking.

Larry

Thank you, Larry. The Vernatherm actually fits into a machined spot on the oil filter adapter. On the #2 opening, you're right; that's not an NPT thread. I just realized that can't work since the oil cooler hose hits the breather fitting (which is just above it) if I try to thread it into the #2 spot. I think I'm going to have to figure out a way to get the #1 plug out and put my fitting down there, and then plug #2. Thanks again!

Heat the accessory case

I used the port on my 320. Just use a 90* hose end. Fits fine. Heat and a breaker bar should help get the plug out.

Larry

Thank you, Larry and Jerry! I'll try heat, but I'll also look for a 90* fitting.

It's been a while, but I dont think you can get a 90 fitting to spin on. You'll need the special cap with the right threads for the accy on one side and an AN on the other side. Most AN fittings are NPT or ORB; neither will work on that #2 hole. Then buy a 90 hose end. The female flare is called a hose end and the male flare is a fitting. In the end, it will probably easier to hone your persuasion skill on that plug.

Larry

Great info! Thanks, Larry!

Plug removal
 

Have seen some tough cases but have always gotten plugs out. I would start with a high quality Allen wrench, preferably a straight section that you can put in the plug and tap home with a hammer. Heat the case around the plug with a heat gun (about hot enough where you can?t keep your fingers on it) insert Allen wrench, give it several good taps and go for it. I have a 3/8? drive set that I would use here, if I didn?t have that I would cut a standard L shaped angle wrench to get a straight section that could be tapped on then turned with a 6 point socket. Good steel wrench gives you best chance to not round off the plug.

Don Broussard
RV9 Rebuild in Progress
57 Pacer

"Can't touch it" is only about 150F. A painted case allows an accurate temperature reading with a cheap infrared thermometer. Run it up to 400F if needed, maybe less if the paint begins to brown.

Principle here is the aluminum expanding more per degree than the steel plug, so every extra degree is in your favor.