150 exhaust and front oil sump nut

[8413]

Hi,
I just got my engine back from overhaul. My mechanic and I had to remove the oil sump to install the 150 exhaust bracket under the front sump nut. We have turned down a 7/16" socket almost paper thin and still can't get it on the nut to be able to tighten it fully. The sump nuts are MS21044N4 nuts. It seems like when I removed the exhaust bracket prior to the overhaul that the nuts were lower profile than the MS21044N4 nuts seems to be. Is there an acceptable lower profile nut I can use? My mechanic had all kinds of specially modified tools and none of them will work due to the super tight working space the exhaust bracket creates.
Josh

[6643]

For the sump I prefer MS21042-4 nuts. They're all metal stop nuts and have a reduced size hex for easier installation in tight quarters.



Technically, nylon stop nuts shouldn't be used on an engine.

[8413]

Thanks John! That will make installation so much easier!
Josh

[8413]

The MS21042-4 nut worked great! A standard (no modifications required) 5/16" universal drive socket did the trick. Thanks for your help John Cooper!
Josh

[6643]

T'was naught!

[8425]

• Are those cracks in the weld of the added support and the weld bead next to the nut on the oil tank?

[8413]

8425,
If you are talking about the left support in the picture (right support if you are sitting in the pilots seat), I think those are shadows from the angle I was holding the light. I looked at the original picture and zoomed and they don't look like cracks to me. I will double check next time I'm at the hangar.