The Cessna 120-140 Association Forum

I just noticed a bolt missing on the backside of the oil sump that also holds the exhaust bracket in place. Does anyone know the part number for a replacement bolt/washer and also torque? Thanks!

It's a stud that screws into the accessory case, then nut and washer. Since it fell out, the new stud will probably not hold. There may be is an oversize stud you can use, or drill it and saftie it.

Stud 401804 1-1/16"x 1/4" Oversize parts are available, see Continental C-series Parts manual.

It calls for plain washers and elastic stop nuts. Both have Continental part numbers, 20522 and 22661 respectively. There is a reduced hex, metal stop nut available. It makes installation a lot easier. MS21042-4.

Torque for the nut can be found in AC43-13.1b. Installation of the stud is probably discussed in the C-series Overhaul Manual.

Something about that support bracket doesn't look right...

Thanks. Yeah like the diameter of that bracket hole is too small. Makes me think if there has ever been a stud there

Maybe I’m missing something, I probably am, but could I drill out the bracket hole to a larger diameter and just put a bolt in place there?

mbruffy wrote: ↑Mon Sep 09, 2024 1:23 pm Maybe I’m missing something, I probably am, but could I drill out the bracket hole to a larger diameter and just put a bolt in place there?

Possibly, or the hole is just an optical illusion? You can try a bolt, it's probably coarse thread........... Studs typically have a slightly different thread pitch, be careful as you screw something in there. I'd try John's recommendation first.....

Yeah, the threads in the accessory case will be coarse, and you will have a hard time finding a bolt to fit.

I think that's a blind hole, too, so if your bolt is too long you'll cause more problems.

That bracket must have been secured at one time or another, so the hole must be the right size for whatever was there. The fact that it fell out points to fixing it right, or you'll be fixing it again. Find out why the holes don't align, and use the right fasteners. Safety wire might be a good idea, too.

What exhaust system do you have on there? Check and make sure you have the correct parts for your installation.

To the naked eye the hole in the bracket looks closer to 3/16 whereas the stud that goes there is 1/4.

Thanks for the advise. They’re straight pipes.

mbruffy wrote: ↑Fri Sep 13, 2024 7:38 amThey’re straight pipes.

Maybe it's just the angle of the photo, but, that bracket doesn't look right. It appears that one tube intersects the other. They should form a "V" with the flat plate that has the tab with the hole at the point. The part is symmetrical left and right.