New Cylinder issue troubleshooting

[scout88305]

I had a 500 hour C90 with acceptable but low cylinders. I purchased 4 new Millenniums on sale from Airpower at $599 apiece. Sold the used Continetnal cylinders on Ebay yesterday for $849. With the cost of doing valves and or rings, the price of buying new seems pretty good for a top end after my money credit on the old cylinders. Well after 10 hours now in break-in mode when I shut the engine down after it's hot I can hear a squeak when I move the prop back and forth. Sounds like it's coming from the case or cylinders. Sounds like pulling a heavy table on a floor. When the engine cools the squeak goes away. Pulled the screen twice. First time at 5 hours some metal not much, at 10 hours none. Cleaned and rechecked plugs and harness. Checked intakes. Checked compressions and they were 76 across the board. Another note worthy item is the engine idles poorly. It lopes with a subltle miss that I can feel and hear, at cruise it is not recognized. Timing, mags, carburation was never touched. I have normal temps oil and cyl head, good power and even checked fuel consumption at 6 gallons an hour running it pretty hard on mineral oil. Two mechanics are baffled. They checked ring gap at install. Anybody with some advice???? Thanks

 

[bob turner]

Valve guides?

 

[Hyrdflyr]

squeak

I second "Valve guides". I had to pull all four of mine on an 0-200 and have them reamed to end the sticky valve issues.

Run car gas also, if you aren't already.

 

[JimC]

Valve guides. Likely on just one cylinder.

 

[Fortysix12]

Can you ad some Marvel to the gas for a little test?

 

[Steve Pierce]

I am at 500 plus hours on a C90 I built with new Milleniums. Haven't had any problems after the rocker arms were reamed to the middle of the spec to get rid of the brass we were getting from the Superior rocker shafts. Did you reuse your spark plugs. Had this same thing happen on my Dad's new engine that had almost new spark plugs that worked fine on the tester but when we put a new set in it purred like a kitten. Milleniums have a good warranty. I would give them a call.

 

[Roger Peterson]

I had the same squeak on a 0-200 and MMO and 2 more hours took care it.

 

[Roger Peterson]

I just put the MMO in the gas, could try both gas and oil.

 

[WWhunter]

Eric,

Bummer! I would have thought they would have gotten that fixed by now. All my knowledge on engines is pretty much limited to cars but from what the other guys have said about valves sure makes sense. A sticky valve hanging up can be a pain. The only part is when you go to cruise it should stay the same ie...still have a miss. Maybe when flying, the cooling air going through the cowling is just enough to allow the valve guide to release its grip on the valve stem. I'm no engine mechanic so take that for what its worth.

By the way...they haven't gotten to my Champ yet either. I called yesterday and they said maybe they'll get to it next week. If I would have know it would be 3 weeks I would have kept it here and done some flying.

Keith

 

[scout88305]

Thanks for the responses. Ok I'll throw in some Marvel. So far I have used only 100LL. Guess warranty requires it. Will keep flying and keep you all posted. Yea Keith they are swamped. 100 hours on their fleet and the fire aircraft get superior attention because they are state a/c and our tax payers dollars never skimp on those. They are royalty you know so take a number and back seat until we get rain and the fire danger is back to low.

 

[two-12sfernow]

I have had the squeak issue drive me nuts several times and it has generally cleared up about the time I thought we were drawing a bead on the problem. Medication with MMO (in my opinion) is good after oil burn has dropped on new jugs.
You can check with a mechanics stethoscope and isolate the cylinder if only one and sometimes the area of the noise within the cylinder. I have found that occasionally the barrel is a bit choked or a little tight and the clearance is a bit low after cooling from descent/landing.
I would be more concerned with a tight valve guide than a tight barrel if the metal was nil and oil analysis is good.
I have found it the norm to need a carb adjust after a top, especially if the old jugs were getting wheezy. Marginal plugs can give trouble with surprisingly minor improvements in engine compression, gapping them to the minimum will often show improvement (and the need for new plugs).
I would call the millennium folks, you paid the big bucks for new and they have been great with follow-up in my experience.
Just my 2 cents worth, which after a lot of years in this business, I have found to be worth less than purchase price.

 

[Josh]

For what its worth, My Engine on the Waco, Continental w-670 squeaks when I pull it through while its hot, Its the norm for these engines, I think its a combination of things such as valve springs, expansion of the springs against the valve keepers and valve guide, and thin hot oil. P.S. it only does it when its hot and when I pull the prop through slowly. It has always done that with 3 different engines on the plane.

 

[bob turner]

On the spark plug issue, the smaller Continentals are a lot less sensitive to what the plugs are doing than are the larger (at least the 150-180hp) Lycomings are.

By way of a boring story - almost a half-century ago I was told my 65 needed new guides. They told me about how to do it, so I did - then I took one jug to my mechanic, and he ran a ream through it so that it was the same diameter as the one I had just removed. Said it would simply freeze up if I left it the stock diameter.

Another boring story - I have a squeak now and then too. I ignore it, and use MMO. And Car gas 75% of the time. Haven't pulled a jug in years - C85.

 

[scout88305]

**********UPDATED WITH VIDEO********

Hey folks,
Here is the noise I am getting out of a hot C90 engine after 4 new Millenniums. Sound goes away as it cools. Pulled screen twice and no or little metal, engine at low idle runs poor (lopes like a subtle miss), Compressions were #75 across the board. Breather shows about twice the amount of drip than before. 12 hours on the new cylinders. Should I keep flying it?? Called the distributor and they say to bore scope, end gap was checked at install. Valve guide issue seemed out to lunch for the Millennium folks. Well here is the sound. Whatcha think? Am I bear bait heading north to visit Jason up at Hudson Bay?

 

[jason crozier]

Eric, i emailed you about this earlier this evening. Does millenium have any answers? Did you ever try the MMO? I am not sure what it could be but i'll email some guys i know.. try emailing that sound to other engine shops, you may get someone who knows what it may be.

The bears are hungry but as long as you got your equalizer, you may be alright. Ha ha......

 

[cruiser]

http://www.sacskyranch.com/eng213.htm http://www.sacskyranch.com/eng181.htm http://www.sacskyranch.com/eng313.htm
Good luck.

 

[Ron Babos]

squeak

The two sound that I hear on the video are the over center lobe clunk of the cam. That's normal. Some are louder than others. The second squeak sound is not just a Superior problem .I've heard it on OEM cyls as well. It's the rings vibrating from a dry cylinder amplified from expansion of the piston and oil that is hot and thin. Top of the bore usually. A better oil or Marvel may get rid of it as it's a classic lubrication break down on the rings. It's not a problem when the engine is running because of too much speed to scrape the bore clean.
Ron

 

[irishfield]

Was just gonna say ring chatter..but Ron beat me to it...

 

[scout88305]

Thanks all for the replies. I like the last one. Sounds logical. We tore down anyway and found nothing unusual but this/ A small tit and circular wear pattern on the piston pin cap. There was a small wear line in the cylinder bore but nothing more than visible is all. Millennium is sending a replacement but I cannot believe this would make a sound. Also have rocker marks on the covers. 2 different cylinders and the wear occurred in just a few hours 12 or so. Is this an issue??? Eric

 

[Steve Pierce]

I have heard the sound before but don't know what it is. I have seen the wear mark on the rocker cover a lot. Never had one eat through yet.