I'm in the process of getting my first annual completed on the airplane I bought earlier this year and the borescope revealed a slight exhaust valve leak on the number #2 cylinder, compression of that cylinder cold was 65. I installed a EDM 830 a week after i purchased the plane; early on I noticed cylinder # 2 CHT's running a bit hotter than the rest -I always try and keep the CHT's below 380, but during the summer it was near impossible to keep #2 below this number during climb and cruise flight with the cowl flaps wide open without backing down the MP to 20-21. I upload all my data to SAVVY and nothing abnormal has appeared outside a few times #2 reaching 390 for a minute or two. The first thing I did was had my mechanic install all new baffling, this helped a bit.... The plane is going to be down for 8 weeks to have a new glass panel installed as soon as the annual is completed. My plan was to send the carb. to Lycon for a flow test while the avionics were being installed, i'm at 2,300 MSL and the most I would see WOT during climb was/is 22 or so. I still plan to send the carb. for a flow test and possible rebuild due to the fact it's not getting enough fuel, but my question is: should I be doing something about this exhaust valve leak while the plane is down for the next 8 weeks or so? My mechanic is telling me that we should just keep an eye on it and do a compression test every oil change for the foreseeable future. I understand the thought of being frugal and keeping a close eye on the situation, but I doubt the issue is going to be rectified as I continue to fly myself and my family around. Wouldn't I be better off pulling the cylinder and sending it off for an IRAN or?? Any insight is appreciated!

Have you checked your valve springs? The Pponk I work on had a couple broken springs one year, about 400hrs since it was built. Something to check. Also. Does the calve show any hot spots? If it does then I'd definitely send it for overhaul. If you are down anyways and the rest of the engine is running good and is a low time engine I'd probably have it fixed. Should last a long time then.

No crazy discoloration & no hot spots...more of a grey (cloud) look extending past the valve seat. We haven't checked the valve springs.

[email protected] wrote:No crazy discoloration & no hot spots...more of a grey (cloud) look extending past the valve seat. We haven't checked the valve springs.

How many hrs on the engine?

just turned 700 hours

Here are a few pics

Another shot of the exhaust valve

I don't see any reason to take drastic measures with your valve..... As an IA, and also I follow Savvy, I don't see a reason to take a cylinder off yet..... There may be some blowby, buts its not a burnt valve from what I see.... IF YOU MUST feel compelled to do something, then I would recommend to take the valve cover off, and take a look at the valve springs, and maybe change the roto-cap. at $15 a-piece + labor, I start changing those around 1000-1200 hrs.

Pulling a jug, IMHO, is a last resort, reserved for a jug that is in "NO SHIT" fixing to "SHIT ITSELF". But, what do I know!

AND, your compressions are WELL above continentals concerns.

Tangogawd wrote:I don't see any reason to take drastic measures with your valve..... As an IA, and also I follow Savvy, I don't see a reason to take a cylinder off yet..... There may be some blowby, buts its not a burnt valve from what I see.... IF YOU MUST feel compelled to do something, then I would recommend to take the valve cover off, and take a look at the valve springs, and maybe change the roto-cap. at $15 a-piece + labor, I start changing those around 1000-1200 hrs.

Pulling a jug, IMHO, is a last resort, reserved for a jug that is in "NO SHIT" fixing to "SHIT ITSELF". But, what do I know!

AND, your compressions are WELL above continentals concerns.

After seeing pictures of the valve I'd agree with this for sure. I would check the springs just to ensure they aren't broken, but the valve looks good in the pictures.

Start adding Techron to your fuel. I had a leaky exhaust valve on my SQ2 that looked to be just a carbon build up in one spot. I pulled the plug, used a flux brush to bathe the valve and valve seat in Techron. Did that over and over and over and...well you get the idea. Also took a rubber mallet to the rocker arm to pop the valve against the valve seat in an effort to break up the carbon. Then I ran double doses of Techron in my fuel for a couple of months. Next compression check was perfect. That was over 600 hours ago. I run Techron now in every other tank fill. This is an experimental plane so I can do what I want although I would do the same in my 185 "in the interest of safety" (memorize that phrase it will likely come in handy some day, it has for me). Even at 1400 hours now the compression is still high on all 4 cylinders.

[email protected] wrote: I'm in the process of getting my first annual completed on the airplane I bought earlier this year and the borescope revealed a slight exhaust valve leak on the number #2 cylinder, compression of that cylinder cold was 65......

I went through this doing the first annual on my 180.
I'd wanted one since forever, and was determined to "maintain it right".
Had one cylinder about like you describe, only it was right at 60/80.
My mechanic didn't think it was necessary, but I insisted that we pull off the cylinder to get it overhauled.

A few years later, another one came up soft, same symptoms.
Only by now I'd read Mike Bush's article(s) about not being too quick to pull a cylinder.
Plus, more importantly, I'd read the TCM service bulletin (SB03-3) which addresses this issue.
Since it passed the bore scope inspection, and the calibrated-orifice-compression tester procedure,
I just let it ride.
It's been soft for about 3 years now, but is hanging in there (not getting any worse)
and is still acceptable per the service bulletin.

FWIW I wish now that I hadn't pulled that cylinder on the first annual, I bet it'd still be just fine.

I have lapped a few when in your position. I always replace the roto-coil. At 700 hours you might also want to check the lifters/cam on that cylinder while you have it apart.

Tim

Thank you for all the responses. The majority rules, and all of the engine shops & savvy agree too. I actually sent p ponk an email and Norma Knopp took the serial number of the engine that I provided her and a few days later I received a call from the gentleman, Dave is his name, that actually built my engine back in 2013 while he was working for the Knopp’s. He’s now retired; amazes me that Norma tracked a former employee down, he took the time out of his day to call me and they don’t even own the STC any longer! Great customer service - even when there is no monetary benefit, just the desire to lend a hand when someone was looking for some guidance! I can see why they were successful, outside of providing a great engine.