Exhaust and Intake Risers Touching?

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shoffert
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Exhaust and Intake Risers Touching?

Post by shoffert »

Hello,

I'm working through my first annual on my "new" 2002 DA-40.

My IA and I noticed the intake and exhaust riser for the #1 cylinder are actually touching. There don't appear to be any after market parts or repairs.

Is this normal? One IA says he's never seen the two touch, another says it's okay....neither have Diamond experience.

What does the forum think?

Photos attached.

Thanks!
Steve
Intake & Exhaust Riser Far Away.JPG
Intake & Exhaust Riser Closeup.JPG
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Steve
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Re: Exhaust and Intake Risers Touching?

Post by Steve »

Steve:

They are close on mine, but there is about 0.25 inch between them at the closest point:
IMG_3099.jpg
They should not be touching, but as you can see, there is limited opportunity to adjust either the intake tubes or exhaust risers. If they remain in contact I would be worried that vibration or corrosion would wear a hole in one or both...

Steve
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Re: Exhaust and Intake Risers Touching?

Post by Rich »

If they're touching that's not good, as they might be more than just touching but actually placing lateral loads on each other. There does seem to be some aftermarket stuff here. Are those intake manifold chrome plated? It looks like both those and the valve covers are, which would not be stock.
2002 DA40: MT, PF, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210.
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Re: Exhaust and Intake Risers Touching?

Post by Steve »

Chrome plating on the intake tubes supposedly reflects some of the radiant heat from the exhaust riser, and allows a cooler intake charge to the engine. I'm sure it doesn't make a huge difference, but I have seen a number of engines like his. Mine are a bit shiny, but not chrome plated, the result of some polishing when I had my engine apart last summer...
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Re: Exhaust and Intake Risers Touching?

Post by Rich »

Spark plug routing is also not original and of course it's not the original prop. There is definitely some tinkering evident.
2002 DA40: MT, PF, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210.
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Re: Exhaust and Intake Risers Touching?

Post by shoffert »

The engine was overhauled 50 hours ago by a big shop in Florida (previous owner). At the overhaul it got the Hartzell prop via the STC. Logs are at the plane to see if it got new intakes at the same time.

No side loads...it's an honest "barely" touching...just at the slip joint.

Steve, you're certain yours aren't touching? Best I can tell your photo looks just like mine.

Rich, yours is an '02...just like mine...do you have a photo of that side of your motor?
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Re: Exhaust and Intake Risers Touching?

Post by Rich »

shoffert wrote:
Mon May 18, 2020 12:22 am
The engine was overhauled 50 hours ago by a big shop in Florida (previous owner). At the overhaul it got the Hartzell prop via the STC. Logs are at the plane to see if it got new intakes at the same time.

No side loads...it's an honest "barely" touching...just at the slip joint.

Steve, you're certain yours aren't touching? Best I can tell your photo looks just like mine.

Rich, yours is an '02...just like mine...do you have a photo of that side of your motor?
Mine would not be applicable, as I have subsequently installed a Powerflow exhaust. Plenty of clearance, FWIW.
2002 DA40: MT, PF, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210.
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Re: Exhaust and Intake Risers Touching?

Post by Steve »

shoffert wrote:
Mon May 18, 2020 12:22 am
Steve, you're certain yours aren't touching? Best I can tell your photo looks just like mine.
I'm certain - I just reassembled that engine in August. Not touching, but 0.25 inches away. I agree that the photo isn't great, I'll get a better one showing clearance the next time the cowling is off.

What kind of exhaust gaskets are used on your engine? I can't really tell from the picture, but if they are the double copper ones, they are thinner than the Lycoming 77611 2-Hole Spiral Wound No Blow Exhaust Gaskets I've always used:
DSCN6024.jpg
A thinner exhaust gasket would allow the exhaust riser to come closer (although a small amount) to the intake tube...

Steve
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Re: Exhaust and Intake Risers Touching?

Post by Rich »

It's hard to be sure from the pictures but the chrome intake pipes seem to me to have a different shape than stock. The no. 1 pipe looks to start the bend toward the rear slightly further from the cylinder head and not completing quite as many degrees of bend. Could these pipes be 3rd party parts? You might check the paperwork for the overhaul for the parts numbers they used. Offhand, I don't know how you chrome-plate an aluminum alloy. Original Lycoming part numbers for these are 42E22611, 12, 13, 14
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Re: Exhaust and Intake Risers Touching?

Post by Steve »

Rich:

Apparently it can be done:

http://arlingtonplating.com/substrates- ... -aluminum/

although I don't know the airworthiness issues involved. Like I said, I have seen a number of engines with the intake tubes chromed, they may have been on experimentals...
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