Lycoming YIO-390 accessory case port IDs

I received my engine yesterday (finally!!) and figured I'd get the various fittings installed on the rear case today before mounting the engine tomorrow.

I quickly realized that the drawing on page 43-05 (RV-14A manual) bears little resemblance to the IO-390 configuration I received from Lycoming. For instance, the drawing shows the oil temp location immediately adjacent to the tach drive where I have a safety wired cap. The drawing also shows only a milled face adjacent to the oil filter where I have a removable red plastic cap.

I've drawn three arrows on the attached photo. I think I know what two of them are, but the third is a mystery.

• White arrow: oil temperature probe location (If so, where does it get safety wired, since Lycoming used the adjacent location to safety the oil filter?)
  
• Red arrow: upper oil fitting (for one of the oil cooler lines)
  
• Yellow arrow: a complete mystery (????)

The yellow is to the oil breather. The oil temp probe gets safety wired any way you can. I was told to "improvise if possible". As a side note, Vans FWF kit has alum fittings for the oil lines etc and I was told by my tech counselor they should all be steel so as to prevent galling with the stainless steel fittings on the hoses. The other red cap is for the mechanical tach drive and Aircraft Spruce and Vans sell caps for that fitting if you are not using it. Your PMag can feed the RPM value to the avionics.

Nova RV said:

The yellow is to the oil breather. The oil temp probe gets safety wired any way you can. I was told to "improvise if possible". As a side note, Vans FWF kit has alum fittings for the oil lines etc and I was told by my tech counselor they should all be steel so as to prevent galling with the stainless steel fittings on the hoses. The other red cap is for the mechanical tach drive and Aircraft Spruce and Vans sell caps for that fitting if you are not using it. Your PMag can feed the RPM value to the avionics.

Click to expand...

Thanks, Chris. Glad to see I wasn't completely nuts.

I've already got my steel fittings (I never use aluminum fittings FWF if I can help it and certainly not threaded into the engine case) and have begun installing them. You can't see the lower oil fitting below the filter in this photo.

I'm a little irked that Van's doesn't include the tach drive cap in the FWF kit. Even Mitch admitted to me this morning that it ought to be included. Oh, well. What's another Spruce order at this point?

After you change the oil the first time and cut that nice safety wire thingie, you can use that same hole for the oil temp sensor. The crimp end on that wire of course is blocking the hole from additional uses.

Nova RV said:

After you change the oil the first time and cut that nice safety wire thingie, you can use that same hole for the oil temp sensor. The crimp end on that wire of course is blocking the hole from additional uses.

Click to expand...

Yep, I saw that. I thought that I'd wind up safety wiring future oil filters to the fitting below the filter, but you're right - the same hole currently used for the filter could be used for both.

For a moment, I wondered where I could get a safety wire crimper like that, but the urge quickly passed.

I thought about that tool also but there were $500 reasons to stay old school