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M20k 231 exhaust


Northern Mooniac

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You caught my post while in edit...

With the 231 (turbo) you are going to have some limitations.

The exhaust is part of the turbo drive system.

The PF exhaust is an add-on for NA engines to minimize back pressure, increasing hp.

Exhaust wear is exacerbated in turbo planes because of the additional pressure kept inside the system.  Check the wall thickness on the first tube while there... this is the tube from the engine to the turbo.  Highest temp and pressure the system sees.

Best regards,

-a-

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NM, do you have a preffered TIT that you use all the time?

Some people are more religious about keeping things cooler than others...

this is the area where temp matters more... the TIT is further down the pipe from the collector.  So the collector is seeing some very high average temps compared to the single EGTs and the TIT....

PP thoughts only, not a mechanic...

Best regards,

-a-

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NM, I feel your pain.  I'm in the throws of the same issue right now.  Found a leak near the #6 (exhaust dust and blistered paint on the engine mount).  We pulled the whole left side exhaust and sent it to Knisley.  Was supposed to be 2 weeks, but took over 5.  Ugh. Then, once we got it back, big leak on the crossover between the new and old.  Our mistake for not taking everything off and sending it all together.  Good advice above to do that...wish I had known.  I actually didn't realize they basically just rebuild everything instead of patching.  Works for me...I just didn't know.

Knisley basically said it would be another 4+ weeks.  Dawley said the same.  It is killing me having the plane down (I fly quite a bit and hate taking the 'bus'), so I overnighted everything to Aerospace Welding in MN as they indicated 1-1.5 week turnaround.  We will see.

Check those v-bands while you have it apart.  Found a crack on one of mine.  

Good luck!
Vance

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  • 3 weeks later...

Hey @Northern Mooniac,

Congrats on getting it fixed.  I'm curious, what all was done for the repair?

I basically ended up with a completely rebuilt exhaust.  I know they are supposed to keep some portion of the original component in order to 'repair', but I swear each shop basically built a new system.  Anyway, I'm back flying with what I would say is a 100% new exhaust, but it cost many multiples of $500 Canadian.  :mellow:

Thanks!
Vance

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The bigger problem (than high heat), is contact with something on the exterior.  There are at least two heatshields that are just pieces of sheet metal between the collector and other engine components.  Usually they are just bent metal supported at one edge.  Over time, the metal bends down and contacts the collector and then starts to wear a slit along the edge where the heatshield is rubbing against the collector.

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Welcome aboard, 78Vic.

Can you clear up the description of what you are selling?

You might consider starting a new thread specific to your plane and parts...

This thread is more specific to its title. An M20K...

Thread drift is more than OK. It happens often.  But, i’m Thinking, you want people to find what you have...

A proper title will be helpful for that.

Pictures of the 58 M20 are always appreciated! :)

Best regards,

-a-

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