How do you test/find a crack in a case?

[Brandon Sinclair]

I have a strange oil weeping issue and I cannot find the reason for it.  The case gets wet in the area under the oil pressure idiot light fitting.  There is a small rectangular area that I will clean off with brake cleaner and go for a drive and it is wet there again.  It does not seem to be coming from either the fitting or the distributor so I am stumped.  Is it possible to have a crack in that area and if so what is the best way to help locate it?

[SlingShot]

I have seen cases that have had the sensor over tightend, which caused cracks. Have you tried cleaning it, starting the engine and just watching for the leak?

[Jim Ratto]

heat it and watch for oils to come to surface out of crack

[Shubee2 (DSK)]

you can alway put some oil dye in the oil it leaves a yellow stain where the oil is coming from

[TexasTom]

Stock fuel pump?

I had a mystery leak in the same area once and it was at the pump, running down to that exact area.

Just a thought.

It's not the OPS itself ... ?

[kingsburgphil]

I have a strange oil weeping issue and I cannot find the reason for it.  The case gets wet in the area under the oil pressure idiot light fitting.  There is a small rectangular area that I will clean off with brake cleaner and go for a drive and it is wet there again.  It does not seem to be coming from either the fitting or the distributor so I am stumped.  Is it possible to have a crack in that area and if so what is the best way to help locate it?

Simple, time tested procedure, Magnaflux brand dye penetrant inspection kit. It's available at Aircraft Spruce, and it was old when I first used it in 69'.
It's best used prior to assembly when your castings are clean, and you have clear access to all the potential weak areas. I prefer to warm the castings first,
maybe 200 deg f.

Using a UV dye and UV light/glasses can work, if you're patient and lucky. Personally I'd try the clean/heat/weep method first, (credit previous post)

[Brandon Sinclair]

Yes, stock fuel pump.  I will take a look at it.  Thanks for all the tips guys.

[Sarge]

Heat works best for finding hairline cracks... just be carefull!!  My current case has had the oil pressure switch over tightened sometime in it's life and is cracked.  You can solve this by carefully cleaning all oil from the switch hole (take the switch out and let the oil drain back into the case overnight).  I'd reccomend a new OEM switch (021 919 081 D) with a tiny dab of red loctite.  Screw the switch in tight by hand and add about a 1/4 turn with a wrench (the switch has pipe threads... tapered... the more you tighten, the wedge of the taper will spread the crack open).  Let everything sit for a few hours to allow the loctite to cure.  I got lucky and have had no more leak.