Pucker factor of ten with no RV grin!

gmshelley · #1 05-26-2009, 07:36 AM

Yesterday N818GS made it's first flight after 5 years of building. Everything went beautifully untill about 20 minutes into the flight when the engine had a reduction in power

I made a precautionary landing and we had found the #2 cylinder plugs fouled and the belly of the plane covered in oil. There was also oil dripping from the carb. We did a compression check and the #2 was reporting 76 psi. We also checked the cylinder oil return and breather with no problems noted. We cleaned everything up and test ran with no issues. Made the second flight and 15 minutes in we lost #2 again. We lost almost a quart of oil and the EGT and CHT were never as hot as the other three cylenders.
I'm asking for the engine experts to chime in and give me some ideas.

Thanks in advance.

jmbrwn · #2 05-26-2009, 07:46 AM

Not an engine expert, but could you tell what engine you're running? Sorry to hear of your troubles.

Geico266 · #3 05-26-2009, 07:47 AM

What is the history of the engine? How many hours?

gmshelley · #4 05-26-2009, 08:00 AM

Thanks for the prompt replies.
The engine is a O-360 with 0 smoh and 1600 tt.
I had bought the engine after it was overhauled from a builder in NY.
The shop that completed the OH was a reputable builder in the area.

caryr · #5 05-26-2009, 08:05 AM

Well firstly, you are a lucky guy.

Secondly, I wouldn't leave the ground again until I had diagnosed and fixed the problem.

I would offer valve guides and seals as being the problem. You can still have compression with the valve seats being OK and the guides wallowed out.

Oil in the carb ---- it probably just ran down the induction tubes when the engine was stopped and sitting there awaiting further attention.

allbee · #6 05-26-2009, 08:43 AM

I just talked to my guy at the local FSDO. He stated that the rings are not seated in that cylender. He said it's not uncommon. I'm right now running my engine at 2500rpm or better than 75% power. He said to not be concerned until you get to 10hrs. If things haven't gotten better than you might have an issue with the rings not wanting to seat. To get the rings to seat you need to push it. like I said, 2500rpm or better than 75% power. I would put oil in go up over the field, monitor the oil usage and run er hard. just to be safe, I would contact your engine manufacture.

airguy · #7 05-26-2009, 08:46 AM

Is it possible you've got water in the oil? Once the oil reaches operating temp (fits with your flight times before problems) that water will start boiling and could "froth" the oil enough to start dumping large quantities out the breather into the carb, explaining the loss in power and the oil on the belly as well as oil in the carb. In that case, however, I would expect to see fouled plugs on all the cylinders, not just #2. Did you check all the plugs? What about compression on the other cylinders?

On your intake manifold, if you had lots of liquid oil running into the manifold, would the physical layout of the manifold encourage puddling of oil and more delivery to #2 than the other cylinders?

fl-mike · #8 05-26-2009, 08:50 AM

I'd definitely get a second opinion before I flew again. That diagnosis doesn't sound plausible to me.

Perhaps Mahlon (Mattituck) can chime in.

David-aviator · #9 05-26-2009, 09:05 AM

Quote:

Originally Posted by allbee

I just talked to my guy at the local FSDO. He stated that the rings are not seated in that cylender. He said it's not uncommon. I'm right now running my engine at 2500rpm or better than 75% power. He said to not be concerned until you get to 10hrs. If things haven't gotten better than you might have an issue with the rings not wanting to seat. To get the rings to seat you need to push it. like I said, 2500rpm or better than 75% power. I would put oil in go up over the field, monitor the oil usage and run er hard. just to be safe, I would contact your engine manufacture.

I agree.

The write up would lead one to conclude oil is entering the combustion chamber and its route most likely is via improperly seated or improperly installed rings.

Clearly, a major problem is indicated by loosing that much power and oil in such a short flight. To be most safe, #2 cylinder could be pulled and checked for proper ring installation and side wall glazing. If there is glazing, a hone job of the side wall in is order.

If there is a written record of the overhaul, check to see exactly what was done. "Major Overhaul" is a meaningless term without qualification. Does the engine have new cylinders or are they original, simply cleaned up and in service limits? Same with the valves. If the cylinders are new, it probably is a ring seating break in issue. If they are original, something else is totally not right.

AZtailwind · #10 05-26-2009, 09:22 AM

Quote:

Originally Posted by gmshelley

we lost #2 again. We lost almost a quart of oil and the EGT and CHT were never as hot as the other three cylenders.

Seen this before- my vote is #2 is not seating and may need a re-hone and check rings and cyl walls. You would hear the blow-by in the exshaust or carb if a valve was not seated correctly and diff. pressure would be lower than 76/80. yea, I would pull #2...