Engine Break In Experiences - Be patient?

[Becca]

So since many of you have broken in a new engine, I am interested in your experiences.  Our mechanic tells us to be patient, but our CHT's are still running high and I am wondering when we should start to be concerned.

As way of background, we never consumed oil so far, so saying break in is complete when oil consumptions stabilizes doesn't seem to apply.

On the other hand, our CHT's have been running high.  We are having to trail the cowl flaps or lean to noticable speed/power loss to maintain temps <360-380.  We have been told one day we'll be flying it around and we'll just see a drop of 20-30 degrees and we'll be good at break in.   (Side note, our baffling is new within the last 100 hrs or so and in good shape.  Our old engine had no cooling problems at all).  However, I am starting to get concerned, we're 15 hrs in and the CHT's still aren't dropping and require active management through agressive leaning (which really slows the plane down) or trailing the cowl flaps. 

Byron's posted our break in procedure on another thread.   We flew the first hour WFO.  The second hour 75% power, then a half hour of WFO, then 65-75% power (varying RPM from 2200-2700) and mostly LOP after the first hour.   Since then we've been flying it in various configuations, but always at 75% power using a combination of leaning and cowl flaps to maintain the CHTs in the <360-380 range.  All but one or two of our legs have exceed 1 hr, though we haven't flown many legs that exceed 2 hrs.

Anyone had a similar experience?  Anyone out there thing we should be concerned that we aren't seing the CHT's come down yet even after 15 hrs?  Our A&P tells us to "be patient", but many break-in experiences on the internet indicate a CHT drop at around 5 hrs..

 

 

[aviatoreb]

Quote: Becca

So since many of you have broken in a new engine, I am interested in your experiences.  Our mechanic tells us to be patient, but our CHT's are still running high and I am wondering when we should start to be concerned.

As way of background, we never consumed oil so far, so saying break in is complete when oil consumptions stabilizes doesn't seem to apply.

On the other hand, our CHT's have been running high.  We are having to trail the cowl flaps or lean to noticable speed/power loss to maintain temps <360-380.  We have been told one day we'll be flying it around and we'll just see a drop of 20-30 degrees and we'll be good at break in.   (Side note, our baffling is new within the last 100 hrs or so and in good shape.  Our old engine had no cooling problems at all).  However, I am starting to get concerned, we're 15 hrs in and the CHT's still aren't dropping and require active management through agressive leaning (which really slows the plane down) or trailing the cowl flaps. 

Byron's posted our break in procedure on another thread.   We flew the first hour WFO.  The second hour 75% power, then a half hour of WFO, then 65-75% power (varying RPM from 2200-2700) and mostly LOP after the first hour.   Since then we've been flying it in various configuations, but always at 75% power using a combination of leaning and cowl flaps to maintain the CHTs in the <360-380 range.  All but one or two of our legs have exceed 1 hr, though we haven't flown many legs that exceed 2 hrs.

Anyone had a similar experience?  Anyone out there thing we should be concerned that we aren't seing the CHT's come down yet even after 15 hrs?  Our A&P tells us to "be patient", but many break-in experiences on the internet indicate a CHT drop at around 5 hrs.. 

[ELT]

Hi Becca,

I am 30 hours into breaking in an overhauled engine.  Only reused the crank, overhauled/replaced all accessories.  Similar break in proceedure.  At just under 5 hours the CHTs dropped.  First oil change and check at 10 hours.  No oil added  first 10 hours and compression in hight 70s.  We plan to change the oil and check over at 35 smoh.  Temps are all god except oil temp is 1 to 2 ticks off the red line.  Mechanic believes this due to high ambient temps and straight mineral oil.  He wants to change to AD oil.  Is this a good idea to change to AD at 35 smoh?  The rings are seated but what about the lower case parts?

[Lood]

I've put 47 hrs on my new engine now. The first 2 hours of flying was done at the coast - WOT, 2700 rpm, full rich and cowl flaps fully open. After that, I flew it home to 4000' AMSL and after about 10 hours, I started, or was rather forced by the topography to fly at 7500', etc. I never let any one of the CHT's go above 350 degs. Initial oil consumption was about one quart every 4 hours or so, but I did keep the elevel rather high though and much of the oil was probably blown out if I look at the belly. CHT's came down after about 8 - 10 hours and I could gradually start closing the cowl flaps. Since 20 hours, I fly with the cowl flaps fully closed in the cruise, WOT, 2500 rpm, 80 deg ROP and my highest CHT is at 320 deg. Oil consumption has just about stabilzed and I just fill it above level 6 on the dipstick when I do a 3 hour plus flight. Oil was changed at 10 hours and filter cut open and checked for metal.

I was advised that the CHT's, as well as oil consumption would be highish, initially and should then decrease and stabilize. CHT's should never exceed 380 deg and if they come close to it, I would do just about anything to get them down - be it full rich, cowl flaps full open or whatever. I flew many hours with my cowl flaps wide open - even above 150 mph IAS. High temps on any engine is a killer and more so on a new one.

[OR75]

how is the OAT there in TX right now ?

probably not conducive to a good cooling of an engine.

 

[Becca]

Quote: OR75

how is the OAT there in TX right now ?

probably not conducive to a good cooling of an engine.

 

[jetdriven]

at altitude  of 1000-3500 between 70-80 degrees  

[OR75]

just saying that i noticed a large impact of OAT on indicated CHT but i don't have way to quantify. i am sure with sophisticated engine analysers may have.

 

[donshapansky]

I first had this temp issue on a different engine/airframe combo, an IO-520 in a Super Viking Bellanca. I had installed new cylinders, in this case Millenium II's. I noticed that EGT's had jumped quite a lot on climb out and of course CHT's were in the 400's in climb. I had been to the GAMI school just before and remembered that the target EGT's should be 1250 F at full throttle. In my case I was seeing 1450 F across the engine. So we started richening the fuel flow, it took 2 tries to get it correct. We started at 24.4 gph, which is the TCM spec. When I got down to the 1250 F range the fuel flows were at 29.0 gph. My cylinders all dropped in the 350 range even on a hot Texas day.

My Mooney Rocket suffered with similar issues, I immediately had Maxwell start twisting the flows up, after 2 flights I've got it to where on a 100 F day everything stays in 350 - 370F and I'm turboed of course. The old formula used was 1 " per 1 gph, it worked exactly on the Rocket.

If I owned any of these 4 cylinder Lyc's it would be the first priority to richen up until the EGT's hit the 1250 F range and watch the CHT's fall. It's a very simple relationship I learned racing 2 stroke snowmobiles and dirt bikes, any time we saw over 1250 we knew seizure of the piston was soon to follow especially on a fresh set pistons and cylinders with tight clearances. It beats me why most A&P's don't know this or were never taught this during their education and training. But I can tell you very few realize the importance of air fuel ratios as it relates to engine operating temps.

[Oscar Avalle]

Thank you for this great post. I have am overhauled engine on my M20C with a LASAR ignition, about 20 hours total time, and I am experiencing very similar temperatures in my engine... Last Friday I landed inmediately when the CHT reached 500... It was scary. I took off the cowling and reviewed the baffles and the dog house. I have not flown since then, but I hope to do it on Monday to check everything out.

Oscar

Quote: pmccand

My ramblings and notes about high engine temperatures...

I have also had FRUSTRATINGLY high temperatures for which I have requested assistance on this and other web sites after a recent o'haul on my O360.   In my case, I tore the engine down a SECOND time in less than 50 hours, after I found two rebuilt cylinders delaminating nickle from the walls!  I suspect very high temperatures were partly to blame.

 I couldn't get temperatures down after 25-30 hours.  I'd start up and make the taxi and pre-flight as short as I possibly can, rolling as soon as CHT's reach 250 deg F.  Upon climb and just after retracting the gear, I find the temperatures at or near 450-480 degrees, and on a really hot day I push red line.  Climb out is at 120 + MPH with full power, full rich and cowl flaps wide open.  I drop the nose to cool the engine as much as possible until I get 420 degrees or less.  At this setting, I can climb only at about 800 feet/min with a light load.  Gauges and probes are checked for accuracy. Carb modded with the ancient service bulletin for the early 61 engines which richened the mixture, and timing re-rechecked.

What's really scary about this is the temperature would SCREAM above 500 degrees if I came in for a landing with a hot engine and tried to do a go-around.

I made a call to Don Maxwell and asked him what his temp experiences were with the M20B O360 engine. To my surprise, (and without telling him what temperatures I was getting)  he said that #3 is ALWAYS the hottest, 390-420 degrees in cruise is "typical" and upper 400's are not uncommon on climb out.  "That's the way they are", he said. So, based on his report of normal behavior, I decided to fly it as-is. 

In my quest to further lower the temperature, I did the unthinkable...I installed a LASAR cowl enclosure mod, just to see what would happen...and what do you know...CHT DROPPED on climb and cruise by 10-15 degrees with a SMALLER opening!  At least, it didn't hurt to install the mod which suprised the heck out of me.

The biggest improvent was a modification to my flying procedure...  Nose down and climb slower.  Contrary to what most people are doing (as they descend with full power), I make SURE my engine is cooled and leaned properly when descending; just in case I need to make a go-around and want full power.  I shoot for 250-300 degrees just before landing with leaner mixture setting to prevent lead fouling.  Just my unsolicited  ramblings, but perhaps my notes help somewhere.

Phil Mc Ca nD.Less

[jetdriven]

Quote: donshapansky

I first had this temp issue on a different engine/airframe combo, an IO-520 in a Super Viking Bellanca. I had installed new cylinders, in this case Millenium II's. I noticed that EGT's had jumped quite a lot on climb out and of course CHT's were in the 400's in climb. I had been to the GAMI school just before and remembered that the target EGT's should be 1250 F at full throttle. In my case I was seeing 1450 F across the engine. So we started richening the fuel flow, it took 2 tries to get it correct. We started at 24.4 gph, which is the TCM spec. When I got down to the 1250 F range the fuel flows were at 29.0 gph. My cylinders all dropped in the 350 range even on a hot Texas day.

My Mooney Rocket suffered with similar issues, I immediately had Maxwell start twisting the flows up, after 2 flights I've got it to where on a 100 F day everything stays in 350 - 370F and I'm turboed of course. The old formula used was 1 " per 1 gph, it worked exactly on the Rocket.

If I owned any of these 4 cylinder Lyc's it would be the first priority to richen up until the EGT's hit the 1250 F range and watch the CHT's fall. It's a very simple relationship I learned racing 2 stroke snowmobiles and dirt bikes, any time we saw over 1250 we knew seizure of the piston was soon to follow especially on a fresh set pistons and cylinders with tight clearances. It beats me why most A&P's don't know this or were never taught this during their education and training. But I can tell you very few realize the importance of air fuel ratios as it relates to engine operating temps.

[jetdriven]

Quote: oavalle

[Oscar Avalle]

Byron,

Indeed I heard that the LASAR ignition raises the CHT by 40 degrees... and that I should actually install such a device you mentioned in your email...but if I were to do so, the benefits of the ignition disappear.  Now, the question comes up is it worth keeping the LASAR or should I revert to the normal magnetos...?

 

Oscar

[Lood]

Oh, I also have the Lasar cowl closure installed. This certainly made a difference - even on my old engine.

[Mooney_Allegro]

 

I'm in the process of breaking in a factory reman from Lycoming in Las Vegas. I'm up to 35 hours and had to stop, because of the high ambient OAT's, density altitude and cabin comfort.  I hope to resume in another week. The first few hours, I noticed much higher CHT's, but after about 5-8 hours, they've stabilized quite a bit. The first takeoff, they approached and exceeded 400 very quickly...especially cyl #3.  I've been flying with cowl flaps wide open and stay at 5000 MSL or below, which is a challenge around the mountains. I usually head down towards Victorville, CA and ask for a low approach over their runway and that route keeps me 5000'. I've also headed over to Catalina Island on one of the break-in flights after 25 hours.  I'm using full rich the entire time and varying the RPM and keeping 65-75% power. Fuel flow is about 15.5 gph, so my paycheck doesn't last too long! Oil consumption is about 1 qt every 6-7 hours now.  Lycoming tells me to go to 50 hours to be sure it's all broken in, so that's what I'll do. I've always run ROP, so that's what I'll do with the new engine. The old engine was run 50-75 ROP and that engine lasted 2000 hours and 14 years. At 25 hours, I had my MSC perform an oil change, cut open the filter, but they "forgot" to check the oil suction screen like I advised them to do. They told me that the cut open oil filter was completely clean, so they didn't think it was a big deal to check the suction screen.  At 50 hours, I'll have them do another oil change and then switch from Phillips 66 Mineral oil over to Exxon Elite 20W-50, and make sure they check the suction screen this time or I'll refuse to pay my bill if they forget again. Lycoming stresses to check the oil suction screen EVERY time you perform an oil change, especially after the 1st 25 hours.  They also scratched the hell out of the rear of my prop w/the cowling and they had to fix it of course, this was after I told them to be super careful.  One thing that had to be sent out for two weeks of repair was my fuel servo. Everytime I came in for a landing, on roll-out the engine would quit. Nothing I would do would keep it running, except to keep power in on landing and have the speed brakes deployed the entire time on landing. I had 3 different mechanics adjust the idling, but this didn't help, so the fuel servo had to be sent out to B&S in Wichita for repair. They replaced a bunch of parts, and my MSC advised me it's the 4th fuel servo they had to send out for warranty on new engines within the lasts 6 months.

 

[jetdriven]

FWIW our high CHT (360-380 in cruise, LOP, cowl flaps closed) persisted until around 50 hours, when we finished up a 12 hour trip to Sedona AZ and back to Houston. On the leg out to AZ, the CHTs gradually crept down to 330-360. After our return, they were a steady 330. I flew it a few more hours and it was consistently 330. Now some of this has to be because its 80 degrees instead of 90.

I put in a bottle of Camguard and we went to the Galveston air race. It returned a speed of 192.54 MPH and it ran 330 CHT full rich. We were able to lean it to 15 GPH at full power for a 370 CHT.

So in closing, the high (~400) CHT is persistent and doesnt come down until about 40-50 hours. That was the longest 50 hours of my life, I was ready to pull it off and ship it back. After 65 hours we have the final personality of the engine, and it is a sweetheart. 7-8 GPH and 150 knots with a 330 CHT. 23 degrees timing makes a noticeable difference in economy and LOP performance. The new factory engine is also smooth as a rabbit's ear.

[201er]

I'm over 65 hours and it still runs hot (if not for LOP or the cooling weather). I still can't do 100ROP without exceeding 380 on the hottest.

[AndyFromCB]

Well,

I've got about 50 hours or so on my TIO540AF1B installation and only in the last 10 hours or so was I able to start closing the cowl flaps fully during cruise. Prior to that I had a hard time keeping them all under 400. Now, on my last run to Lincoln to drop the plane off for an annual, they are all staying between 360 to 380 even with aggressive leaning to 1650TIT with cowl flaps closed at 75% which in my airplane is about 30/2400. So my experience is very similar to yours, Becca/Byron.

Andy

[jetdriven]

I'm over 65 hours and it still runs hot (if not for LOP or the cooling weather). I still can't do 100ROP without exceeding 380 on the hottest.

Check my spreadsheet, Mike, but yeah, 100 ROP is the hottest CHT I can achieve. 15 LOP is some 30-50 degrees cooler.

[rocketman]

I've got about 50 hours or so on my TIO540AF1B installation and only in the last 10 hours or so was I able to start closing the cowl flaps fully during cruise. Prior to that I had a hard time keeping them all under 400. Now, on my last run to Lincoln to drop the plane off for an annual, they are all staying between 360 to 380 even with aggressive leaning to 1650TIT with cowl flaps closed at 75% which in my airplane is about 30/2400. So my experience is very similar to yours,

Running TIT to 1650 is near redline. I have a TSIO-520 NB and never take it that hot unless I am doing a TIT check for a few seconds to peak (TIT 1700). What is peak TIT for your TIO540AFIB installation (TSIO540AFIB?).

[rocketman]

I've got about 50 hours or so on my TIO540AF1B installation and only in the last 10 hours or so was I able to start closing the cowl flaps fully during cruise. Prior to that I had a hard time keeping them all under 400. Now, on my last run to Lincoln to drop the plane off for an annual, they are all staying between 360 to 380 even with aggressive leaning to 1650TIT with cowl flaps closed at 75% which in my airplane is about 30/2400. So my experience is very similar to yours,

Running 1650 TIT is redline on my TSIO-520 NB and I generally keep TIT at 1580 or less, never above 1600. What is your redline and are you sure the TIT probe is accurate. Have you checked your inflight TIT probe accuracy?

[AndyFromCB]

I've got about 50 hours or so on my TIO540AF1B installation and only in the last 10 hours or so was I able to start closing the cowl flaps fully during cruise. Prior to that I had a hard time keeping them all under 400. Now, on my last run to Lincoln to drop the plane off for an annual, they are all staying between 360 to 380 even with aggressive leaning to 1650TIT with cowl flaps closed at 75% which in my airplane is about 30/2400. So my experience is very similar to yours,

Running 1650 TIT is redline on my TSIO-520 NB and I generally keep TIT at 1580 or less, never above 1600. What is your redline and are you sure the TIT probe is accurate. Have you checked your inflight TIT probe accuracy?

Rocketman,

1750 is the redline on a Bravo. Both TIT probes are fine. 1750 is the only way to get book fuel burn numbers but I'm kind of attached to my exhaust transition which is a 5K part so I run between 1600 and 1650. The valves guides on Bravo's are oil cooled so running 1750 is not an issue for cylinders or valves, but you'll pay dearly replacing exhaust transitions, waste gates and turbos so I run between 50 and 150ROP depending on how high the power setting.

[Lood]

Well, it seems I'm lucky. Got almost 70 hours on my IO360A1A and all temps are rather cool. On a return flight last Saturday, the CHT's rose the highest since stabilizing at around 15 hours - to a max of 347 deg. OAT was 86 deg F. Normally, the CHT's are around 300 deg with #4 always being between 320 - 330 deg.

Oil consumption has just about settled and since the last top up to 7 on the dipstick, during the 50 hour oil change, I have actually flown 16 hours and the level is now down to 6 on the dipstick. Most seems to have been blown out the breather though, looking at my F's belly. The level has been sitting around 6 for at least the last 4 hours and it seems that I will only have to top up for a long flight.

I rather well informed person reckoned that if an engine hasn't settled after 25 hours, the break in might not have been successful.