Breaking in rings on one cylinder

[nels]

My E model went in for annual and the rear cylinder on passenger side, I think that would be number three, was low on compression. They pulled the cylinder , checked valves, honed cylinder and replaced the ring set with new. I'm wondering if I should use break in oil, how do I initially run it etc. Also, the engine had not been run in two months and a compression check was done without starting the engine to reseat things. I half wonder if the low compression on one cylinder was misleading and the maintenance unnecessary? Any thoughts. I think I might start pushing a tennis ball up the exhaust pipe when I leave it for an extended amount of time. At least this would stop any drafts through the combustion chamber.

[jetdriven]

We just went through that twice. Our 250 hour factory engine shows high iron and chromium, suspected ring wear. Borescope on the #4 looked the worst, so we pulled it and measured everything, couldn't find anything wrong. Put it back on with the original rings and the oil in the sump which included camguard. The cylinder glazed over and then wore all the cross hatch out. Good compression at 74/80 but using a quart every 3 hours.

This time we honed it and used new rings, flew it 5 hours like a bat out hell with straight 50W mineral oil. I think it took.

Anyways , the compression test is supposed to be done hot on an airplane thats flown recently. Used to be if it was below 60/80 it had to come off but often if you fly it 30 minutes it comes back high 70s. The oil film breaks down and surface rust forms on the walls. The compression test in this case is misleading.

[garytex]

I have had good results breaking in single cyls on Phillips 20-50 (no cam guard till later)

[MB65E]

Awe man!!! It would have come up fine even in the 50/80 range. As for the brake in Aeroshell 100 mineral oil, no additive. High power. 5 hours should be enough at high power.

I sometimes switch back to mineral oil on an engine that might sit for 6 months or so.

-Matt

[nels]

I thought mineral oil would be the way to go but not sure why you would not use cam guard?

[MB65E]

It actually lessens the friction on the rings and lengthens the brake in time.

Per Several engine builders and Cam guard directly.

I just finally put cam guard in after 65hrs...

-Matt

[Seth]

Don't put camguard in until you know the rings are seated. Sometime after 50-100 hours on your cylinders depending on cylinder type, oil burn rate, how often you fly, etc

-Seth

[aaronk25]

When I overhauled, which included new Pistons, rings and a cylinder hone ( and other parts) the cylinders broke-in, in about the first 3 mins of climb as evident by chts dropping off.

The worse thing you can do is make your camshaft and lifters which already have wear and tear on them run with mineral oil just to "break in" a new set of rings.

The advise of Ed who invented Camguard was to go fly it 20 mins and dump the crank case oil and leave the filter installed. Refill with 20w-50w phillips. Run a few hours dump oil again , refill with the phillips again and run 15 hours or so and change oil and filter.

Any wear metals in the filter stay there. The object is to get the oil that is contaminated with blow by out of the engine.

Blow by is super pro-wear and our marginal cam and lifters are prone to failure from the abrasive contaminates.

Ed said a lot of failure on cams occur on frequently flow engine with top or new cylinder parts.

[N601RX]

A newly honed cylinder will have sharp ridges due to the crosshatch. These will go away pretty quickly, but during the 1st 5 hrs will make a lot of really fine particles. After installing new wrist pin caps which are now brass you can hold the filter media up to the light and see a gold tint to it. This will go away after the 1st oil change.

[MB65E]

All true! I was just hoping to knock rust of the cam with the mineral oil... Lol.

-Matt

[jetdriven]

A newly honed cylinder will have sharp ridges due to the crosshatch. These will go away pretty quickly, but during the 1st 5 hrs will make a lot of really fine particles. After installing new wrist pin caps which are now brass you can hold the filter media up to the light and see a gold tint to it. This will go away after the 1st oil change.

The newest wrist pins caps are Bronze-aluminum.  Note that Blackstone doesnt check for bronze, but perhaps the alumimum component will show in the analysis.

[jetdriven]

All true! I was just hoping to knock rust of the cam with the mineral oil... Lol.

-Matt

Id prevent rust on the cam at all cost. its actually the lifters, but still. No matter what dont let it sit more than 14 days in a humid climate.

[John Pleisse]

 

Put it back on with the original rings and the oil in the sump which included camguard. The cylinder glazed over and then wore all the cross hatch out. Good compression at 74/80 but using a quart every 3 hours.

 

Wuh??? I have done a top and bought factory new. 50 hour min-oil break-in and both times satbilized at over 10 hours. That's just wrong.

[FloridaMan]

My E model went in for annual and the rear cylinder on passenger side, I think that would be number three, was low on compression. They pulled the cylinder , checked valves, honed cylinder and replaced the ring set with new. I'm wondering if I should use break in oil, how do I initially run it etc. Also, the engine had not been run in two months and a compression check was done without starting the engine to reseat things. I half wonder if the low compression on one cylinder was misleading and the maintenance unnecessary? Any thoughts. I think I might start pushing a tennis ball up the exhaust pipe when I leave it for an extended amount of time. At least this would stop any drafts through the combustion chamber.

 

That doesn't pass the smell test to call pulling a jug and having it overhauled after the engine didn't run for two months. Also, your IA should have very specific instructions for you regarding cylinder break-in. I know that before I picked up my Mooney after a cylinder overhaul that the A&P had a procedure where he would run the engine for short periods of time to help seat the rings and I assume there may've been a follow-up torque sequence as well. We ran Philips 20/50 and I was instructed to stay at 25"/2500 RPM for several hours. 

 

Where are you located? If I were in your situation, I would find a recommended A&P in the area, explain what you're going through and get their advice. It may be worth paying another mechanic for an hour or two of labor to ensure that the cylinder has been properly torqued and that there are minimal other issues. 

[jetdriven]

That doesn't pass the smell test to call pulling a jug and having it overhauled after the engine didn't run for two months. Also, your IA should have very specific instructions for you regarding cylinder break-in. I know that before I picked up my Mooney after a cylinder overhaul that the A&P had a procedure where he would run the engine for short periods of time to help seat the rings and I assume there may've been a follow-up torque sequence as well. We ran Philips 20/50 and I was instructed to stay at 25"/2500 RPM for several hours. 

 

Where are you located? If I were in your situation, I would find a recommended A&P in the area, explain what you're going through and get their advice. It may be worth paying another mechanic for an hour or two of labor to ensure that the cylinder has been properly torqued and that there are minimal other issues. 

That is bad advice and it is not backed up with published data anywhere.

 

the A&P had a procedure where he would run the engine for short periods of time to help seat the rings

---------you must fly the airplane to seat the rings, ground running is detrimental to ring seating since there is not enough cylinder pressure to seat rings. Running at high power on the ground will overheat the engine. Fly it.

 

and I assume there may've been a follow-up torque sequence as well.

-----I've never read this. Torque the cylinders once on installation.

 

We ran Philips 20/50

---ECI recommends it. Although it is AD oil I am OK with using it for break-in.

 

and I was instructed to stay at 25"/2500 RPM for several hours.

-----Lycoming specifies maximum allowable power for the first hour or so, and thereafter 65-75% power while varying the RPM, for at least the first 5 hours.  Occasionally increasing to maximum allowable power occasionally.

[Andy95W]

and I assume there may've been a follow-up torque sequence as well.

-----I've never read this. Torque the cylinders once on installation.

 

.

Personal experience after replacing a cylinder on my last C model. Torqued new cylinder properly. Ran the engine for 5 hour break in period as recommended. Engine ran well, but... different. Didn't feel right.

Checked torque of my new cylinder and it had backed off. Re-torqued and the engine felt and ran perfect.

Since then I have always checked the torque of all cylinders I've installed AND use torqueseal. Very low cost. Peace of mind- priceless.