The Cessna 120-140 Association Forum

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

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.

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

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

T'was naught!