Oil breather fitting and hose

#1 02-22-2007, 11:12 AM

I'm considering changing my oil breather fitting from the straight version that came with the Mattituck TMX-IO360 engine to a 45-degree version, but I have some questions:

1. Is this just a standard AN fitting with pipe threads on one end and a hose barb on the other? It doesn't "look" like a standard aluminum fitting, but I've been told by at least one parts salesman that this is just a standard fitting. The same parts guy wanted $40 for a 45-degree fitting, but that seems awfully expensive for an AN844 fitting.

2. Will a 45-degree fitting actually screw into the completed engine, or will the hose barb piece interfere with the side of the case when I try to rotate it?

3. Is MIL-6000 hose (which was recommended to me by the engine manufacturer) significantly more flexible than automotive radiator hose? MIL-6000 ain't cheap, but I may be willing to pay a premium for hose flexibility.

Thanks.
-Geoff

RV-8

zilik · #2 02-22-2007, 12:28 PM

I can't answer your question about fittings but I do have an opinion about the breather hose. (Doesn?t everyone!) Automotive heater hose is not suitable in this application since it is not oil resistant. In short order it will start to sweat oil and look like old dynamite. The hose quickly deteriorates and could start to collapse on the inside possibly blocking the breather. There has been more than one RV forced down due to breather hose obstructions. Do yourself a favor and use the a milspec hose.

f1rocket · #3 02-22-2007, 02:23 PM

I had a problem on my engine when I wanted to re-direct the oil breather line in a different direction. I went to the airplane parts isle at Home Depot and purchase brass plumbing solder fittings. I screwed in the elbow and then soldered on the straight piece, since there wasn't room to clear the back of the engine block.

frankh · #4 02-22-2007, 02:47 PM

I was going to go the copper home depot solution except that I had an invert system, thus the top hose became the oil pick up hose when upside down. Clearly don't want a substandard hose in this event.

I found the the 45 deg brass hose fitting (which is a standard hose fitting with 1/2" male pipe thread) would not tun in the threaded hole. Seeing as I needed a "proper" hose fitting anyway I had to got for a swept fitting so i used hose and fittings from Summit Racing which wern't too horiffic cost wise.

As stated above, the rubber hose HAS to be oil resistant. I I.e not radiator hose.

frank