Engine port confusion

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KinzuaBearhawk

Bearhawk QB Companion
Can someone please explain what the three red plastic ports are designed for on this simple Lycoming o-360 carbureted engine with p-mags. I am getting conflicting information. Just looking to hookup oil cooler. Any advice is greatly appreciated.IMG_4551.jpeg
 
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Disclaimer - Check with Lycoming, but I think... the capped fitting facing aft is the oil cooler out (back to the engine) and oil to the cooler is a fitting that should be located low underneath the right side PMAG and slightly more inboard. The other capped fitting was used for a viscosity valve for engines without spin on oil filters. Both serve as oil from cooler to the engine paths. One will be capped with big plug...your choice. Seems like you have a fitting in place on one of those? Please check with Lycoming or your favorite engine guru and let us all know!
 
Here’s how I would do it. You are missing some fittings. I would use steel fittings, and seal the pipe threads with Loctite 565 or whatever sealant you prefer instead. No goo on the 37 degree flares which will be male on the fitting and female on your firesleeved hoses. If you are not going to use the mechanical tachometer, you can buy a nice cover for that port, which has provisions for safety wire.
 

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Screenshot 2026-08-27 at 9.25.56 PM.pngThe Magenta Arrow is where the Viscosity Valve resides if one is installed. Viscosity Valve, Aka a Spring & Plunger, is removed with the oil filter mount you have installed. The Spring & Plunger is an older design, the Vernatherm is the new and your filter assembley has one.
 
You want to become familiar with some Lycoming documents for your engine. I consider four almost essential.... Type Ceftificate Data sheet, the Lycoming Parts Catalog, the Lycoming Operator Manual, and the Overhaul Manual. If you want to further your knowledge, download, read and make an index for a 100 page document called Lycoming Flyer Reprints.
 
Bcone1381 said:
You want to become familiar with some Lycoming documents for your engine. I consider four almost essential.... Type Ceftificate Data sheet, the Lycoming Parts Catalog, the Lycoming Operator Manual, and the Overhaul Manual. If you want to further your knowledge, download, read and make an index for a 100 page document called Lycoming Flyer Reprints.
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Thanks. I just printed the parts and operator's manuals. That is very helpful.
 
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The Breather Tube just lets the case breathe. Air will flow out of that port due to blow-by. Air will have some oil droplets. Fabricate and install the Breather Hose as the last hose/line you install before you install electrical wiring. I made mine of 3/4 inch aluminum tubing and 3/4 ID flexible silicone tubing. Mine is a straight fitting with a male pipe thread into the case and a barbed end on the outlet. BTW, i labeled all those ports on my engine. YOu can still see my Tach Drive label.

Did I mention the usefulness of a Lable Maker?
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If aircraft specialty said you can just slip a hose over the threads and clamp it, then I am sure it okay. There isn't any pressure involved and saves buying another fitting. Don't forget to put a 1/4" hole in the tube within the engine compartment. Without it, if the breather outlet freezes in cold weather you will blow an engine seal. The higher you can route the hose before it descends the more oil you will recapture.
 
Thanks guys.
Bcone1381 said:
The Breather Tube just lets the case breathe. Air will flow out of that port due to blow-by. Air will have some oil droplets. Fabricate and install the Breather Hose as the last hose/line you install before you install electrical wiring. I made mine of 3/4 inch aluminum tubing and 3/4 ID flexible silicone tubing. Mine is a straight fitting with a male pipe thread into the case and a barbed end on the outlet. BTW, i labeled all those ports on my engine. YOu can still see my Tach Drive label.

Did I mention the usefulness of a Lable Maker?
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Good idea. Thanks for the picture.
 
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