I0-360 Intake Gaskets goop em or not?

[Grandmas Flying Couch]

I know bits a pieces of this have been discussed before and I've researched other forums but I haven't been able to draw a useful conclusion.  My engine misses at idle and then has an after fire in the muffler.  I don't like this happening although it doesn't happen in flight.  I'm installing a JPI 830 soon but don't have engine monitoring yet.  In searching for the problem I checked the intake bolts and they were fairly loose taking at least a turn to get 96 in-lbs.  After twerking the bolts to 96" the misfire seemed to disappear and the engine ran smoother (could have been in my head).  Its a week later and the pops and farts are back and my engine is also misfiring.  

Time to change gaskets, I've ordered both the lycoming and superior gaskets. 

Three questions:

I also ordered the red o-ring gaskets for the other end of the intake tubes. Do the large O-rings have to be changed after removing tube or can I clean up tube, lube the end with clean oil and stick it back in?

Do you guys use goop such as permatex #3 avaition, on the paper gaskets or do it dry?

If you are in the pro-goop crowd, which is your favorite gasket sealer for this purpose?  How about power grab, hold it tight for 30 seconds and go fly!

Thanks, Adam 

Edited November 25, 2017 by Grandmas Flying Couch

[jetdriven]

Definatelt permatex aviation sealer on the paper intake gaskets. They leak without it and good luck leaning it with a tight spread. 

If you’re careful you can reinstall the silicone o-rings and Jen pipes right back into the the intake plenum. But here’s the deal, if you go 3/4” too deep with it then the o-ring pops out the backside of the machined bore it rides in, and the backside edge  of that bore is sharp.  You rip the. O-ring getting the pipe back out. So have a spare. 

Edited November 25, 2017 by jetdriven

[Guest]

I prefer high temp silicone gasket maker on both sides of the gasket, it make future removal and clean up much easier.  After hundreds of hours the gaskets dry out, crack and can be really stuck to the cylinder head, making removal and clean up a chore.

The O rings can be lubricated with oil or DC4 compound.

Clarence

[mooniac15u]

Are you working with an A&P on this?  What advice have they given you?

[Grandmas Flying Couch]

7 minutes ago, mooniac15u said:

Are you working with an A&P on this?  What advice have they given you?

Yes, Im working woth an A&P, should be assumed.  I called him after posting and he wants them dry since manual doesn't mention sealant.  So I have a set of superior gaskets on order from spruce. 

 

On 11/25/2017 at 11:26 AM, jetdriven said:

Definatelt permatex aviation sealer on the paper intake gaskets. They leak without it and good luck leaning it with a tight spread. 

If you’re careful you can reinstall the silicone o-rings and Jen pipes right back into the the intake plenum. But here’s the deal, if you go 3/4” too deep with it then the o-ring pops out the backside of the machined bore it rides in, and the backside edge  of that bore is sharp.  You rip the. O-ring getting the pipe back out. So have a spare. 

Thanks for the advice, sounds like it can be a gotcha if the ring goes in too far.  

 

23 hours ago, M20Doc said:

I prefer high temp silicone gasket maker on both sides of the gasket, it make future removal and clean up much easier.  After hundreds of hours the gaskets dry out, crack and can be really stuck to the cylinder head, making removal and clean up a chore.

The O rings can be lubricated with oil or DC4 compound.

Clarence

Thanks doc, i have clean oil around so will probably use that.  Thanks for the help.  I have to go dry though since my IA has final say.  

[jetdriven]

I changed the factory intake gaskets on #1 and #3 after maintenance. The engine would shut off clean and cold when the throttle was pulled to idle. I actually had trouble starting it. Turns out I had to raise the idle with the stop screw by one full turn. Anyone who has done this knows its a lot. Thats how much air was leaking past those gaskets at idle.  Since then, Permatex aviation sealer for all those paper gaskets, valve cover gaskets too. And since then, I havent had to replace any for leaks.

[Grandmas Flying Couch]

Just now, jetdriven said:

I changed the factory intake gaskets on #1 and #3 after maintenance. The engine would shut off clean and cold when the throttle was pulled to idle. I actually had trouble starting it. Turns out I had to raise the idle with the stop screw by one full turn. Anyone who has done this knows its a lot. Thats how much air was leaking past those gaskets at idle.  Since then, Permatex aviation sealer for all those paper gaskets, valve cover gaskets too. And since then, I havent had to replace any for leaks.

If they leak after this, ill convince my mx, or I'llget the sign-off from someone else.  Thanks! Hopefully they wont leak.  On my cars Ive always used permatex products vs dry with wonderful results.  Since the manual doesnt state specifically, he wants to go by book, says insurance could use it as an out in case pf emergency.  

[N201MKTurbo]

If you push the o-ring through, you can get it back out in one piece. Just twist it as much as possible and pull straight. Squirt some of your favorite lube in it.

I have never gooped them. I can't imagine how a tiny leak at that point could effect the mixture in any measurable way. Especially at cruise power. The pressure differential between the inside and outside of the pipe is very little. The air leakage would be miniscule compared to the airflow through the riser. I have had the whole riser come off in flight and the engine ran fine. I just had to push the mixture knob in farther. Which is how I knew something went wrong.

[Grandmas Flying Couch]

Lol thats my kind of guy, push a little extra calls for a little extra fuel, relax.  

Just now, N201MKTurbo said:

If you push the o-ring through, you can get it back out in one piece. Just twist it as much as possible and pull straight. Squirt some of your favorite lube in it.

I have never gooped them. I can't imagine how a tiny leak at that point could effect the mixture in any measurable way. Especially at cruise power. The pressure differential between the inside and outside of the pipe is very little. The air leakage would be miniscule compared to the airflow through the riser. I have had the whole riser come off in flight and the engine ran fine. I just had to push the mixture knob in farther. Which is how I knew something went wrong.

 

[jetdriven]

6 minutes ago, Grandmas Flying Couch said:

If they leak after this, ill convince my mx, or I'llget the sign-off from someone else.  Thanks! Hopefully they wont leak.  On my cars Ive always used permatex products vs dry with wonderful results.  Since the manual doesnt state specifically, he wants to go by book, says insurance could use it as an out in case pf emergency.  

The only thing insurance wants is a copy of the last annual log entry.  You can follow the book, you can also add sealer to a gasket to do the job a little better. The book deosnt say to add thread sealer to tapered NPT pipe threads on the accessory case, but with 110 PSI oil, you had better. Its standard mechanic practices and techniques.

Edited November 26, 2017 by jetdriven

[N201MKTurbo]

8 minutes ago, jetdriven said:

I changed the factory intake gaskets on #1 and #3 after maintenance. The engine would shut off clean and cold when the throttle was pulled to idle. I actually had trouble starting it. Turns out I had to raise the idle with the stop screw by one full turn. Anyone who has done this knows its a lot. Thats how much air was leaking past those gaskets at idle.  Since then, Permatex aviation sealer for all those paper gaskets, valve cover gaskets too. And since then, I havent had to replace any for leaks.

Idle is the only place where it would make a difference. The pressure differential across the gasket is the highest there and the fuel flow is not being metered by the servo. Even though as long as it stayed constant you could adjust it out.

[Grandmas Flying Couch]

Thanks, Ill push the issue with him.  A little appropriate goop never hurt anything.  

[Grandmas Flying Couch]

Just now, N201MKTurbo said:

Idle is the only place where it would make a difference. The pressure differential across the gasket is the highest there and the fuel flow is not being metered by the servo. Even though as long as it stayed constant you could adjust it out.

This is the problem i am chasing, a miss at idle with afterfire.  

[N201MKTurbo]

1 minute ago, Grandmas Flying Couch said:

Lol thats my kind of guy, push a little extra calls for a little extra fuel, relax.  

 

With a massive leak in the intake manifold there wouldn't be as much air going through the servo, so the servo would be providing far too low a pressure to the injectors. by pushing in the mixture you are telling the servo to supply the correct amount of fuel with less airflow.

[N201MKTurbo]

What usually happens is the lip on the top of the riser tube wears into the groove in the flange and the top of the tube will sit below the surface of the flange. This causes a poor seal. If you dress the top of the flange with a file till it is level with the tube lip it will seal without goop.

[N201MKTurbo]

6 minutes ago, Grandmas Flying Couch said:

This is the problem i am chasing, a miss at idle with afterfire.  

This is usually caused by a very rich idle mixture. Leaking gaskets would cause a lean(er) mixture.

Bring it over and I will make it idle like a sewing machine...

[Grandmas Flying Couch]

Where are you based? It has to be within 50 miles as im only a solo rated student till jan.  

[Grandmas Flying Couch]

Im kgyr

[N201MKTurbo]

19 minutes ago, Grandmas Flying Couch said:

Where are you based? It has to be within 50 miles as im only a solo rated student till jan.  

Chandler.

[Grandmas Flying Couch]

2 hours ago, N201MKTurbo said:

Chandler.

Now i have a new awesome problem, probably related! Now engine wont shut down with ICO.  I pull mixture engine runs great, checked cable travel is stop to stop.  Turned on boost pump with idle cutt off and watched for 30 psi, then shut off pump and it immediately leaked down.  Bet mixture valve is shot.  

[jetdriven]

Its fuel injected. Confirm the cable pulls it to ICO hard. if so, Ship fuel injection system for overhaul.  Mikes fuel metering in Tulsa did mine, its fine.

[N201MKTurbo]

It correlates with your idle problem. The flow divider is what shuts off your engine. When there is not enough pressure to push the diaphragm up against the spring the plunger hits the bottom and closes off the passages stopping the engine. If your idle mixture is too rich the pressure will not deacrease enough for the flow to shut off.

[jetdriven]

The mixture Is one thing but the ICO is two disc with holes that turn far enough for the Holes not to line  up at all, and shuts off the fuel. I would disconnect the mixture cable and manually throw the arm full travel before pulling it. Our mixture cable developed a thing where it would get tight and jam just before ICO. It felt cut off but it wasn’t. And it flooded on start and wouldn’t start up. 

Edited November 27, 2017 by jetdriven

[Guitarmaster]

Just did this on mine. Great way to find a leak!

Sent from my XT1585 using Tapatalk

[Grandmas Flying Couch]

12 hours ago, jetdriven said:

The mixture Is one thing but the ICO is two disc with holes that turn far enough for the Holes not to line  up at all, and shuts off the fuel. I would disconnect the mixture cable and manually throw the arm full travel before pulling it. Our mixture cable developed a thing where it would get tight and jam just before ICO. It felt cut off but it wasn’t. And it flooded on start and wouldn’t start up. 

I check to see that it was hard against the stop on servo.  Has to be a cut-off valve issue.  I did a simple test where I disconnected the cable like you recommended and made sure it was ICO, then I fired up the boost pump until I had full pressure (about 30 psi).  After shutting off boost pump, I saw the pressure drop, this is different to what has happened in the past.  I will have mech remove valve and see if it can be lapped.