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Dear all,

For 2 months I’m following a leak that I have noticed on the riser of cylinder #2.
My engine was overhauled 350hr ago in 2016.

Last july, I noticed a leak that I was able to see on the inner bolt of riser of cylinder #2. At this moment I saw that there was a crack in this riser, first i repaired it (welding) then (today) I changed the riser by a new one, I also replace the seals.
But either after réparation by welding and today after replacement with a new riser, it continues to leak.

The leak is really “small”, but it leaks.
We have looked inside the cylinders and it appears that cylinders 2&4 are more oily than cylinders 1&2.
My oil consumption is 4 qt added in 50h.
My Blackstone analyses are perfect.
Mag cut test are ok.
Oil filter doesn’t reveal any metal particles.
Compression were ok at last annual in may 2020.

The pictures below were taken after a 10’ engine test on the ground.

Do you have an idea of what it can be ? What would you do?
My mechanic is not worried at all, but I don’t like leak.
My friends (with rotax engines), are worrying me...

Thanks for your help!

Arnaud.

Have you been torque checking the exhaust nuts? It seems strange that with a new riser and a new gasket that the leak would continue if it is in fact coming from the exhaust port. I would replace the plain exhaust nuts and toothed washers with locknuts.

Davestation wrote: ↑Mon Oct 05, 2020 1:16 am Have you been torque checking the exhaust nuts? It seems strange that with a new riser and a new gasket that the leak would continue if it is in fact coming from the exhaust port. I would replace the plain exhaust nuts and toothed washers with locknuts.

Hello,

From what I remember, they have not been torqued, because they are not easily accessible, but all are mounted like this.
They are thighten hard, but not with torque tool.

It doesn't seem that it can come from elsewhere as the surrounding parts of the engine are very clean.

Arnaud.

What I mean is have you checked them again since the new riser was installed to see if they are still tight?

Davestation wrote: ↑Mon Oct 05, 2020 6:45 pm What I mean is have you checked them again since the new riser was installed to see if they are still tight?

Nope I didn’t, but the pictures were taken only after a 15 minute period of running the engine on the ground after installing the new riser.