OIL LEAK...

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2066
Posts: 600
Joined: Tue May 01, 2018 7:00 am
Name: Mac Forbes
Location: North Carolina
Aircraft Type: '46 Cessna 140
Occupation-Interests: Retired - Current 120-140 Assoc. NC Rep.
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OIL LEAK...

Post by 2066 »

...looking at a neighbor's 120 this weekend that had developed a pesky oil leak. It appeared to be coming "up" from a stud through the oil temp housing. A new gasket didn't solve the problem...and, then, we spied what we should have seen to begin with -- a crack (pic, below). A NOS housing is on the way from Fresno & should solve the problem...'though I must admit some concern over why it cracked (It had been on for "many years", so maybe overtorqued to stop a leak at some point?). Mac
IMG_2596  JOES OIL SCREEN HOUSING CRACK.jpg
IMG_2596 JOES OIL SCREEN HOUSING CRACK.jpg (75.41 KiB) Viewed 1858 times
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6643
Posts: 2482
Joined: Tue May 01, 2018 7:00 am
Name: John C
Location: KLCI, NH
Aircraft Type: 1946 C140/C90
Occupation-Interests: A&P, semi-retired
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Re: OIL LEAK...

Post by 6643 »

Good catch! It would have been a bummer if that thing came off in flight!
4004
Posts: 249
Joined: Tue May 01, 2018 7:00 am
Name: Edd
Location: KFGU TN
Aircraft Type: 140
Occupation-Interests: Retired
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Re: OIL LEAK...

Post by 4004 »

Mac:

You meant "oil screen" housing per photo annotation - that contains the temp bulb - logical since one is on order - and the -8 case does not have a separate housing.
If it is the -12 case, then a possible root cause analysis may be that the crack (in time) was caused by the use of the wrong attachment hardware.
From photo, it looks like the washer directly against the housing is an internal tooth lock washer and the sharp edge of such may have created a
stress point at the housing interface. Parts manual calls for the oil filter housing to be installed with "plain washer and plain nut".

Just a stretch.......
2066
Posts: 600
Joined: Tue May 01, 2018 7:00 am
Name: Mac Forbes
Location: North Carolina
Aircraft Type: '46 Cessna 140
Occupation-Interests: Retired - Current 120-140 Assoc. NC Rep.
Contact:

Re: OIL LEAK...

Post by 2066 »

4004 wrote: Tue Mar 23, 2021 1:45 pm Mac:

You meant "oil screen" housing per photo annotation - that contains the temp bulb - logical since one is on order - and the -8 case does not have a separate housing.
If it is the -12 case, then a possible root cause analysis may be that the crack (in time) was caused by the use of the wrong attachment hardware.
From photo, it looks like the washer directly against the housing is an internal tooth lock washer and the sharp edge of such may have created a
stress point at the housing interface. Parts manual calls for the oil filter housing to be installed with "plain washer and plain nut".

Just a stretch.......
Yep...and since the photo annotation was mine you'd think I'd get it right :( . Interestingly, the TCM OH manual reads "If the engine is a -12, -14, -16 or 0-200 place plain washers, lockwashers and plain hex nuts on all crankcase cover retaining studs, except the one through the generator mount pad." (This is an 0-200, incidentally.) That appears to vary from the parts manual...so wonder which is correct? Mac
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