Intake and Exhaust Gasket ?

Working on reinstalling the intake and exhaust tubes on my engine after performing the wobble test and ensuring that I don't have a sticking valve. That story here: http://www.vansairforce.com/community/showthread.php?t=151957

I have 4 of the blue fluorosilicone intake gaskets that I never installed due to the reports of low torque required to keep them from squeezing out and due to Vlad's reports and pics of them after hundereds of hours. Botom line is I don't plan to use them.... If anyone wants them, drop me a note.

There are reports here of people having good success using the copper 75118 gaskets on the intakes including Vlad which is likely the king of RV hours flown per year.

Originally my engine had the spiral wound blow proof gaskets and when I removed the exhaust I did find some slight evidence that they were leaking a bit around the flange. All the grey haired mechanics I talk to say "Blow proof won't blow out but they will leak!"

So I am possibly looking to replace both intake and exhaust gaskets with 75118 solid copper gaskets. (update: Since people I trust have spoken, I will be reinstalling the exhaust with blow proof spiral wound gaskets.)

Lycoming SI 1204D states that when using the 75118 gaskets on the exhaust that they must be used in pairs, nested with each other with the bead towards the exhaust.

For those using 75118 gaskets on the intakes, do you use 1 or 2 of them and which way should the bead be installed?

My opinion is that you should continue using the "blow proof" gaskets. They are less likely to leak than doubling the copper gasket, which you should double if using.

Also, a friend with a warranty on his engine called Lycoming (while troubleshooting a problem) and was told that using the copper gasket on the intake was not approved and would void his warranty.

Well Brian, this is one old, gray-haired mechanic that has had nothing but good luck with the Blow-Proof gaskets, and no good results with other methods of sealing exhaust. If you had a leak, I'd suspect that you didn't have good torque on the nuts.

Most leaks I have seen are due to the surfaces already being compromised - if they are like new, the blow-proofs are the way to go. If the surfaces are compromised, they need fixing, or they'll keep leaking, no matter what.

I know I am not old enough to se everything yet, but I have not seen blow proof exhaust gaskets leak when installed properly.

Vic

Raymo said:

My opinion is that you should continue using the "blow proof" gaskets. They are less likely to leak than doubling the copper gasket, which you should double if using.

Also, a friend with a warranty on his engine called Lycoming (while troubleshooting a problem) and was told that using the copper gasket on the intake was not approved and would void his warranty.

Click to expand...

Ironflight said:

Well Brian, this is one old, gray-haired mechanic that has had nothing but good luck with the Blow-Proof gaskets, and no good results with other methods of sealing exhaust. If you had a leak, I'd suspect that you didn't have good torque on the nuts.

Most leaks I have seen are due to the surfaces already being compromised - if they are like new, the blow-proofs are the way to go. If the surfaces are compromised, they need fixing, or they'll keep leaking, no matter what.

Click to expand...

vic syracuse said:

I know I am not old enough to se everything yet, but I have not seen blow proof exhaust gaskets leak when installed properly.

Vic

Click to expand...

Other than failing to torque the nut properly and ensure smooth & clean flanges, pretty hard to screw this one up.

I already have new blow proof ones in hand, what advice do you have to ensure no leaks other than the obvious ensure clean flanges and torque the nuts to spec?

As for long term maintenance to keep them from leaking, do you guys keep a check on nut torque on a regular basis and does the nature of the gasket eventually run out of compressability and need changed?

The flanges on my exhaust are good as new. Will check those of the cylinders out good but I did not notice any damage to their faces either. My vote is on Paul's mention of nut torque. I did not keep torquing them down often.

Thanks to all of you for your advice!

Gaskets

I am an old gray haired guy and I have tested both the 77611 blow proof and the copper gaskets with the v groove 75118. Yes the copper ones need to be installed in pairs if you use them and if you torque them up and then decide to take the exhaust off even if you haven't started the engine, you must replace them. Not so with the blow proof, they can be used a number of times. So listen to Paul and Vic as they are correct. Make sure your flange is not warped and the exhaust port is not eroded and they will seal up.
I agree the copper 75118 are not to be used as intake gaskets even though they will fit. Vetterman

Larry, thanks for your advice and experience and your exhaust. It is a thing of beauty!

Looks like 4 out of 4 votes for blow proof! Good thing I already bought em!

Also love the mass of knowledge and experience and willingness to share and help from all of the experimental aviation participants!