So I am breaking in my 8-T RTR today. Once I got past the first slobbering rich tank and a broken starter box belt, I readjusted the HSN and LSN to 3 turns out. I was able to keep the temp at 200-220 with it still running rich and spitting fuel by putting foil on the head.

Everything was fine for the first 4 tanks, and I varied the throttle, didn't go crazy. I did a couple full throttle bursts for a second or two during tank 5, easing the throttle on an off - the usual stuff. After every tank I let it cool and would pour out the left over oil from the muffler, and it just looked like clean used oil.

Near the end of tank 5, it started sounding weird. The idle was just not right like it was going to die, which was strange because the rest of the break in the idle was no problem. Then the temp started going up suddenly from 200 to 230 - very fast. Before I could shut it down it flamed out. The piston was frozen and I thought it was just stuck at TDC but in fact when I turned it over I saw my mark for BDC at the bottom. I could barely move it a BDC and I thought the rod went or a bearing.

I used a screwdriver to move the flywheel but the piston was so tight at the bottom I thought this is not good. When I dumped the extra oil from the muffler this time it was grey - like there was very fine metal shavings in it. Again, I thought not so good. So I let it cool and put some after run oil and cranked it on the box and it turned over. I thought well either it is busted or it isn't so time to find out and run tank 6. Put in a new glow plug because they can do weird things when they are going bad.

I fired it up and it ran OK, again the temp was anywhere from 190- 210 - seemed fine and I leaned it to 2 1/2 turns on both needles. Seems OK now but the weird episode freaked me out a little bit. I ran tank 7 and no issues, so I guess if something let go I would know it. Anyone have any experience like this during break in?

No replies as yet. Hopefully I can get it out later today and see how it goes!

This can happen when a brand new engine is not broken in yet and get overheated too much.
I have seen you previous post about your break in and saw the one with running too rich.
My brother have had this happen too him with the 454 also.
The engine is just too damn tight in the beginning. He got up to about 240 or over very fast and the engine just seized and would not budge. That you saw metal shavings is not good but nothing you can do about now.
Perhaps you temp gun is showing a bit off too.
Lets say you got to 230 but you are actually at 250 or so... not a bad thing on an engine already broken in but on these tight one it becomes a problem.

(just to comfort you, my brother and I broke 5 belts on two starter boxes breaking in two 454's)

Thanks bro for the info. I was really careful during the break in but who knows. I wish I hadn't idled the first tank very rich, even though that is what Losi says is an option. I'll heat cycle it a few more times and see what happens!

Idle'ing the first tank is not a bad thing. It enables the engine to gently wear in the piston and sleeve without too much strain. Rich as H€LL is the right way to go. As rich as you can go without stalling. You don't need to worry about the "getting up to temp" this early.

Well I tried to run it again today and there is definitely a problem internally. I can get it started and it idles - almost like clockwork when it gets to about 160 the idle starts going up and end then becomes impossible to slow down - then the temp starts rising fast and it flames out or I shut it down before it really starts screaming. I don't think it's an air leak since its brand new and worked fine until the end of the 5th break in tank. I think it's a rod bearing or rod issue but I won't take it apart because I think Horizon should warranty it. Something went south very fast with this engine after it was broken in carefully. After it got stuck at BDC I knew this would not be a good ending. We shall see what Horizon says, I am shipping the engine to them tomorrow.

very lean LSN.

Set a factory setting 2 1/2 turns out - if that was the case would it idle fine until it got to 160?

i doubt factory is that far in. try 4 full turns out. make idle gab .7-1mm then lean lsn one hour at a time untill it idles

call horizion and see what they say first...sounds like either a bad rear bearing or lower rod bushing.....running any motor that rich is killer on the rod as it puts stress on it due to the extra fuel in the combustion chamber....i've seen pistons crack, rods snap, and crank pins shear within a couple tanks if things are to rich...

Thanks for the post. Believe it or not the Losi 454 manual says 2 1/2 turns out on both the HSN and LSN but I think you are right - I did a little searching and found a lot of people that said the specified 2 1/2 turns for each is way too lean!

From the factory the actual settings were HSN 4 1/2 out and LSN 3 1/2 out but that was so rich it would barley run or heat up at all.

I have a few nitro cars but this is my first Losi and I have never seen the supposed "factory" settings so far off.

Never again will I run a first tank that rich. I knew better but thought I'd follow the manual. And I left it at the settings they had from the factory. Dumb. But if I reset them to what the manual specified it would have been way too lean. Should have just leaned the HSN some until it quit choking on fuel. Dumb.

I too have found the factory settings on this engine to be way too lean. You have to remember that you adjust your engine's tune to your environment. I truly think your engine is fine it is just too lean on the low end. The way the temps rise on these engines is nuts because of how tight they are. You do have to run them rich ( but not fuel spitting slobbering rich) or the temps will climb fast. The good news is that once you stick it out and get her fully broke-in the engine runs great and will last a long time. I have about 9 gallons on mine and she runs like a top, I race with my 454. I also changed the bearings out at the 6 gallon mark.

Can you take the engine apart and post some pictures? Thats the only way you will know if it's ok or not. You could also look inside the exhaust port and see if the piston is scratched up.

From personal onroad engine experience I use. 16 percent nitro with 9 percent oil but add an extra 200 cc of castor for break in. Do this for a gallon and she is ready to go. You can run the engine pretty close to race tune, although it will blow lots of smoke and not have as much power as normal fuel will have but it will be almost impossible to ruin the engine during break in. Running the engine at normal running temperatures with a lot of oil is better than running the engine rich at lower temps and low oil. You will have to mess with the needles when the gallon is done. Putting foil over the head is also a good thing to do for the first half gallon.

Tower hobbies sells klotz benoil, that what I use for castor.

Thanks for the advise guys. This engine has really got me feeling like an idiot. I'm no expert but I'm not a newbie either. I have broken in other engines and never had issues like this.

I will take the advise received here and try the re-tuning adjustments before sending it in. I would REALLY feel stupid if I sent it in and there is nothing wrong with it!

I don't want to take it apart in case I do look to get it warrantied. But based on what I see through the exhaust port the piston and sleeve look fine.

I'll post the results after I try if out, even if it turns out to be "operator error."

I appreciate everyone trying to help me out.