Exhaust Gasket

[Guest]

4 hours ago, spleecho said:

Sorry not sure what you mean by that can you explain? Not sure I got enough torque on it right now

From the Lycoming Direct Drive overhaul manual, 204”Lbs torque.  The stud is a 5/16-18NC thread.

Clarence

[spleecho]

1 minute ago, M20Doc said:

From the Lycoming Direct Drive overhaul manual, 204”Lbs torque.  The stud is a 5/16-18NC thread.

Clarence

I believe with my wrench to socket setup might have under tightened, getting ANY socket on one of the nuts is not possible. It's just about touching the pipe.

[takair]

2 hours ago, spleecho said:

I believe with my wrench to socket setup might have under tightened, getting ANY socket on one of the nuts is not possible. It's just about touching the pipe.

You need to grind a socket to fit.  

[takair]

This is an old Snap-On 1/4” drive, 1/2” socket that is ground down and fits even the tightest stacks.  Very difficult to get enough torque without a small diameter socket.  Just happened to be putting the exhaust back on today.

[spleecho]

Finished everything last night. One bolt was just impossible to do with even ground down socket to the breaking point but got it done with wrenches. Everything turned out good thanks for your help!

Pretty proud of my ELT install

 

 

 

 

 

[carusoam]

Congrats on the completion...

Got a CO monitor in the cabin...?

In the event something comes loose, the first hint may be an elevated CO level on the monitor...

PP thoughts only, not a mechanic.

Best regards,

-a-

[spleecho]

Congrats on the completion...
Got a CO monitor in the cabin...?
In the event something comes loose, the first hint may be an elevated CO level on the monitor...
PP thoughts only, not a mechanic.
Best regards,
-a-

Yes both paper and electronic one. Thx

[65C_flier]

On 11/22/2019 at 11:22 AM, M20Doc said:

From the Lycoming Direct Drive overhaul manual, 204”Lbs torque.  The stud is a 5/16-18NC thread.

Clarence

@M20Doc
Trying to figure out what torque to use on exhaust stud nuts. MM seems to say 100-110 in.lb, but are we saying it needs to be 204 in.lb?

[carusoam]

C_f

Doc gave 204 in-LBs....

Check to see if your threaded studs are the same dimensions as the ones he is referring to...

Best regards,

-a-

[Guest]

10 hours ago, 65C_flier said:

@M20Doc
Trying to figure out what torque to use on exhaust stud nuts. MM seems to say 100-110 in.lb, but are we saying it needs to be 204 in.lb?

I’ve always used the Lycoming value for torque.  They made the stud and nut so should know what torque it can sustain.

Clarence

[A64Pilot]

Ref cleaning off old cork gaskets, put a wire brush in one side of your bench grinder and the cork just disappears, takes about 30 sec per cover.

I learned this on car valve covers 45 years ago, then we glued them on with 3M weather strip adhesive, so they were REALLY stuck on.

Oh, obviously use a gasket scraper to remove most of it first, the wire brush is for the stuck on stuff.

‘Once you have that wire brush you’ll find many uses for it, for instance it will take rusty bolt threads and make them look new in just a few seconds, but be careful because it can also launch bolts and things with significant velocity

[A64Pilot]

On 4/11/2021 at 7:50 AM, M20Doc said:

I’ve always used the Lycoming value for torque.  They made the stud and nut so should know what torque it can sustain.

Clarence

Maybe, but the FAA will disagree with you, the aircraft MM takes precedence, the aircraft manual is supposed to call out a different torque if for some reason it’s more correct in that application. 

[Guest]

What a maintainer to do?  Most vintage Mooney manuals are vague on torque values, even the more modern manuals are vague.  I’ll stand by using Lycoming values in absence of better info.

Below are screen shots from every Lycoming powered Mooney manual.

Clarence

[A64Pilot]

I don’t understand what your showing me?

All I’m saying is that the aircraft manufacturers manual if there is a discrepancy between it and the engine manufacturers manual, the aircraft manufacturers manual takes precedence. Go to the engine manual if the subject isn’t covered in the Airframe manual.

‘Sometimes a manual is wrong too, if so we are supposed to go through the procedure to correct it, it happens. I’ve seen foot lbs called out where inch lbs was correct.

‘A tire manual may for instance call out 30 to 40 PSI, but if the airframe manual says 50, you should run 50.

Some think the components manual would be the best data, and you would think so, but using the tire example, maybe the airframe manufacturer determined that 50 PSI reduced the number of prop strikes

[N201MKTurbo]

I asked one of the IAs I used to work with before I got my license what the torque value was for some engine bolt. He said German Tight. I asked what that meant. He said to make it Guten Tight....

[A64Pilot]

7 minutes ago, N201MKTurbo said:

I asked one of the IAs I used to work with before I got my license what the torque value was for some engine bolt. He said German Tight. I asked what that meant. He said to make it Guten Tight....

There are times we all do that, but the book answer is that there isn’t a fastener on the aircraft that doesn’t have a torque value, if the manual doesn’t call it out specifically, then you use a general torque chart to determine value.

I ran an aircraft assembly line for awhile and the only things that were torqued were those specifically called out on the drawings, and there was only a very few items that were. We were FAA inspected of course and they knew it, so I finally gave up.

[N201MKTurbo]

14 minutes ago, A64Pilot said:

There are times we all do that, but the book answer is that there isn’t a fastener on the aircraft that doesn’t have a torque value, if the manual doesn’t call it out specifically, then you use a general torque chart to determine value.

I ran an aircraft assembly line for awhile and the only things that were torqued were those specifically called out on the drawings, and there was only a very few items that were. We were FAA inspected of course and they knew it, so I finally gave up.

How many of us torque the access panel screws? They are almost always too tight.

[Marauder]

I can tell you what happens when they are overtightened. You end up declaring an emergency and doing an impromptu landing. 

[takair]

I have wondered if the torque called out for the exhaust stud nuts accounts for the gasket type?  For example, if using the “no blow” gaskets, The no blow spring material is thicker than the part that holds it.  So, when installed, there are two gaps under the exhaust flange at the point where torque is taken up.  The result is, when torqued, a thin exhaust flange ends up warped, especially at the ears.  This then contributes to leaks and cracks.  In other cases, if the exhaust flange is heavier, when torqued, you may still end up with gaps between the exhaust flange and the ears on the gasket and the cylinder head.  The torque is primarily taken up by the spring material, but I think both situations are sub-optimal as far as torque on a part where there are huge temperature extremes.  The old metal gaskets provide a more constant surface for torquing, but....they “blow”.  Seems the ears on the no blow gaskets should be a little thicker than they are...closer to the thickness of the compressed spring material.  

[N201MKTurbo]

2 hours ago, Marauder said:

I can tell you what happens when they are overtightened. You end up declaring an emergency and doing an impromptu landing. 

I hate it when that happens!