What's that white stuff?

h2oavi8r

SPONSOR

Silverdale, WA

• Jul 24, 2021

• #1

This morning I noticed a very fine white powder around the #1 exhaust manifold (Sutton STC). It has faintly coated the exhaust pipe mount, spark plug end and wire and some has drifted over on the intake pipe. My next door neighbor was having an annual done today on his L-3 so I asked his mechanic to look at it. He says it is an exhaust leak and suspects that it is coming from the pipe joint. He noticed that there is an extra band of metal under the clamp and is wondering if that is the normal installation. Also he thinks he sees sealant in the joint. Is that normal? He is familiar with the Sutton STC but has never installed one. He has a Grumman exhaust that he took off a neighbor’s Tiger and is going to look at it and research the STC when he gets home.



I’m pretty sure the white powder has been there for some time but I never paid it much attention until now.


I'd like to hear ideas about what the issue is, what the fix is and how soon I should get it done.


Also, is it safe to keep flying until it’s fixed and if so, how much?

I always appreciate the wealth of knowledge and experience here!

Thanks,
Robert

 

skukum12

MEMBER

The Last Frontier

• Jul 24, 2021

• #2

Fix it now. Any exhaust exiting from the wrong place can lead to CO poisoning. Take this time to do a thourough inspection of your firewall and seal any holes. CO is serious business.

 

D

dgapilot

FRIEND

• Jul 25, 2021

• #3

When I see lead bromide on spark plugs and wires, it is usually from the exhaust flange gasket. If that’s where it’s coming from, continuing to run the engine will erode the exhaust flange on the cylinder requiring it to be machined. Fix it now before you have a more expensive repair.

As for sealant on the clamps for the Sutton exhaust, the STC does call for a sealant, don’t recall the name right now, but if you read your STC installation instructions it is there.


Sent from my iPad using Tapatalk

 

J

Joe McMillen

Registered User

Dyersburg, TN

• Jul 25, 2021

• #4

Exhaust leak. Very dangerous!

 

E

eskimo77

Registered User

Kenai, Alaska

• Jul 25, 2021

• #5

If silicone is used to hold the exhaust gasket in place while installing the exhaust, it will cook and leave a white powdery substance. Even the high temp silicone.

 

S

stewartb

MEMBER

…

• Jul 25, 2021

• #6

Exhaust leaks leave streaks of gray-white soot but nothing clumpy. Lots of guys use a dab of RTV to hold exhaust gaskets in place for assembly. I don’t but I know good mechanics that do. I prefer self-flagellation.

 

wireweinie

FOUNDER

Palmer, AK

• Jul 26, 2021

• #7

Flo-ex. Goes on as a THICK liquid and hardens with heat. Fairly easy to clean after disassembly.

And be sure that you have blo proof gaskets and not the skinny little old style gaskets.

Web

 

h2oavi8r

SPONSOR

Silverdale, WA

• Jul 26, 2021

• #8

wireweinie said:

Flo-ex. Goes on as a THICK liquid and hardens with heat. Fairly easy to clean after disassembly.

And be sure that you have blo proof gaskets and not the skinny little old style gaskets.

Web

Click to expand...

I’m not familiar with flo-ex. Please explain what it’s for and how to use it for this situation.

The exhaust was R&Red to pull a cylinder during the annual in March by Steve Pierce so I would bet he used the better gaskets. :lol:

Thanks!

Robert

 

wireweinie

FOUNDER

Palmer, AK

• Jul 26, 2021

• #9

Coat the exhaust gasket with it and when the cylinder heats up the Flo-ex solidifies and helps seal small gaps. The key description is 'small gaps'. If the exhaust flange has been tweeked or the exhaust port surface is eroded, no sealer will work well.

Web