What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Is My Engine Broken In?

macrafic

Well Known Member
Background: Just completed RV-7A. IO-360 engine new. Started with 7 qts of oil, with the assumption that the better part of 1 qt would go to the oil filter. At 2.0 (tach)/3.5 (hobbs) hrs, I added a quart of oil. Probably could have waited another 2-3 hrs, as not quite a quart had been consumed. I now have 13.8 (tach)/16.8 (hobbs) hrs and am not needing to add additional oil yet. Maybe another couple of hours? So, in summary, I have 11.8 (tach)/13.3 (hobbs) hrs on this last quart of oil.

CHTs are behaving, but I did not unfortunately record the very initial CHTs at a particular power setting for a current comparison. As a result, I don't know if I have experienced the 50 degree drop in CHTs that I have heard about (as another indication that the engine has broken in).

In trying to summarize the various VAF posts on oil consumption, it seems to be the general opinion that 10 hrs per qt is a pretty decent consumption. Obviously, some are getting less and some more than that. So, I am definitely above that. I have read Lycomings documentation, but they only specify the max allowable oil consumption, not a desirable range. They also only specify a maximum schedule for mineral oil (25 and 50 hrs), with a stipulation that the key criteria is stabilized oil consumption.

So, the questions I am pondering. With so few hours, could the engine already be broken in? The oil has gotten much darker the last couple of flights, so I would like to change it. Should I again use mineral oil or go to standard oil?

Anybody have any other perspectives/thoughts/experiences that I should contemplate as I make these decisions? Any thoughts welcome.
 
I just put rebuild Ram cylinders on my TCM IO550. Ram says cylinders will be broken in after 1st hour....and they were. CHTs down (not nearly 50 degrees!) and stable oil consumption. You do run it hard for that hour.
 
Sounds like the cylinders (rings) are broken in but the rest of the engine may still be in progress. I would suggest (based on MFG recommendations) you stick with mineral oil for the first 25 hours. Change after the first 10 then after another 25 (total of 35).

I started sending samples to Blackstone after the 3rd change at around 85 hrs.
 
Keep in mind that many of our engines will not hold 7, even 6, quartz without puking some out the breather. So, until you learn where your stable oil level is, oil consumption can be hard to judge.
 
There of different thoughts on this but here goes. On a New Lycoming I like to change the oil after the first five hours and the second oil change at 30 hrs total time. I am also a big advocate of doing a oil analysis. Every engine is different but it seems most will blow out oil over 6 1/2 Qts on the stick.
 
Break in

This can be like the debate between tail wheel v. nose wheel, but here goes. My YIO360M1B was purchased new from Lycoming and came "Broken In", it was run in the factory and ready for use on recept. Nothing in the way special treatment was require. I did change oil after 5 hours and now after 150 hours engine has no issues.

I have also had 4 engine overhauls done on various engines by the same local shop. A Continental O300, 470, and two Lycoming 320's. The overhaul mechanics break in recommendation was the same for all these engines. Minimal run up on the ground, full power climb to 10,000 feet, powered descent to landing. Change oil....break in complete. Some may agree or disagree but none of the engines have developed any problems in their service so far and the hours vary from 500 hours to 2,100 hours in service.
 
Appreciate all the feedback guys. I really do.

However, several of you pointed to the Lycoming documentation, which I have read. The operative phrase in that documentation, after stating hours, is "or until oil consumption stabilizes". I am trying to figure out what to look at to determine that.

While each engine is different, maybe the key here is, how many hours have others taken to break their engine in? Is there a number or a range that seems to be the case, with exceptions of course?
 
When is engine broken in

I installed new O-540 2 years ago. First hour was critical to run hard at low altitude to burn rings into cylinders. Next 10 hours still ran just straight mineral oil and considered it break in time. After 50 hours oil use is low but compression's were 76, 77, etc Switched to mineral oil with additive. And now 100 hours later it uses very little oil and compression's are 78, 80 etc. I think it kept breaking in for the first 100 hours and now it is tight.
 
Appreciate all the feedback guys. I really do.

However, several of you pointed to the Lycoming documentation, which I have read. The operative phrase in that documentation, after stating hours, is "or until oil consumption stabilizes". I am trying to figure out what to look at to determine that.

While each engine is different, maybe the key here is, how many hours have others taken to break their engine in? Is there a number or a range that seems to be the case, with exceptions of course?

I've seen engines with an hour and half factory run-in that broke in within an hour of flight time, others took five, others took ten....and some just keep burning oil.

In reading your original post, I couldn't get a clear picture of how much you are burning NOW. If you keep tripping it to 7, as you stated you put in up front, then you're pumping oil out the breather, not burning it. So now if you start at 6, how long does it take to get to 5? If that's 10-12 hours or more, you're probably done.

This is assuming standard Nitrided cylinders. Other cylinder finishes can vary widely.
 
Keep in mind that many of our engines will not hold 7, even 6, quartz without puking some out the breather. So, until you learn where your stable oil level is, oil consumption can be hard to judge.

Yup, my O-320 promptly barfs out anything above 6.5 quarts. My Warrior, also with an O-320, did exactly the same thing, only its number was 7.
 
I think you are looking for oil consumption to stabilize, it?s going to settle in at some number you typically see hopefully greater than 8 hrs/qt. and stops improving. Stops improving is the key.
I?d change it early if you haven?t yet, set it carefully at the 6qt level. I put 6-1/2 qts in my 0-360 with a filter change to land on the 6qt level. Then wait until it gets to the 5 qt level and check the hours.

Tim Andres
 
Appreciate all the feedback; getting what I want in the last few posts especially. The hint about 6.5 quarts (instead of the 7 that I initially did) is a good piece of advice.

Changing the oil tomorrow. Will use 6.5 quarts instead of 7. Run it down to 5 quarts and note the hours.

Because I wasn't clear in my initial post, this last quart that I added (the only quart I have added since draining the preservative and adding 7 quarts of mineral oil) brought the dipstick to 6.5 quarts. Since then, I have run off 15 hours and am not quite at 5.5 quarts on the dipstick yet.

So, I am toying with the idea of switching from mineral oil to regular oil at tomorrows oil change. Without a doubt, I am getting bored with running the engine hard for 15 hours to break in, and not being able to test the things that are important, but require slow flight (clean/dirty stalls at various flap settings, pattern power/speed settings, landings, etc.). Hope that boredom is not causing me to rush things with the oil!
 
Because I wasn't clear in my initial post, this last quart that I added (the only quart I have added since draining the preservative and adding 7 quarts of mineral oil) brought the dipstick to 6.5 quarts. Since then, I have run off 15 hours and am not quite at 5.5 quarts on the dipstick yet.

A quart in 15? If it was mine, I'd say it was broken in about as much as it is going to get. I also suspect that it went down from 6.5 to 6 more quickly that from 6 to 5.5, because most of these engines in RV's blow out anything over 6.
 
There is no reason you have to postpone testing your critical things like stall speeds or slow flight. Your engine isn't going to just decide all at once to glaze cylinders. You taxi at low power, you land at low power, regardless.
What you want to avoid is continuous extended low power operations. A few minutes of testing won't hurt a thing.
Run hard, test for a bit, run hard, repeat....
 
Back
Top