Put this is the category of you don’t know what you don’t know…  The attached photo shows two fittings.

The top one (actually two) is from the bottom of a TSIO0550 oil cooler where it feeds the turbo’s (for cooling) - at least that’s what was on my engine and seems to reflect the diagram in the TCM manual.  The bottom one is functionally the same thing but is a single fitting that I got from a local hydraulic fitting supplier.

Is there a reason that TCM used two fittings when they could have got by with one?

It appears the original(s) might be brass and steel (plated).  I’ll re-check when I’m out at the hanger.  The new/bottom one is steel (plated).  Perhaps there is some issue with the steel fitting in the aluminum oil cooler housing (galvanic/seizing), or perhaps they intend the brass fitting to be softer when attempting to get it in/out (if it’s stuck), or ????

Anyone have any insight before I insert the new one?  I was going this way because I desired the shorter fitting for better hose clearance/alignment.

Rick,

 

I don't know, but I love the torque wrench used on the top reducer fitting.  Was it a calibrated pipe wrench or just the clamping pressure on the vise-grips?

 

Here's something else I don't know - A single piece fitting that reduces a tube connection has some interesting characteristics (bottom picture).  If the flow is towards the pipe thread, turbulence is created after the hole ( @#%^$#^%# with respect to fuel flow sensors).  If the flow is towards the flared end, the sudden restriction may have an adverse effect on the flow rate (less than that of a smooth pipe of the smaller side diameter of the reducer).  On the other hand, with the reducer/flare combo (top pic), the flow towards the pipe thread side produces less turbulence as the line more gradually increases in diameter thru the use of the fittings.  And, if you have a third hand, flow towards the flare end is more tapered and, perhaps, less adverse to the flow.

 

In other words, I don't know if I don't know whether the bottom one is functionally equivalent to the top one.

 

I hate Al-Al pipe fitting connections.  Without a good lubricant/sealant, galling of one or the other piece is highly possible.  At least steel or brass can only cause galling on the Al side (later able to be fixed with Heli-coils).  Oh, you call that seizing.  Steel/Al doesn't seem to be a worrisome galvanic marriage since there are many engine parts that match up steel to aluminum - sleeve in the head, valve seat inserts, valve guides, spark plugs in heli-coils, bolts holding the case halves together, etcetera, etc.

 

Now I don't know if I'm just having a bad day or I really don't know.