Engine "Run" in Disaster
 

I had a shocker today. Before I start I have broken in about 10 .21 engines and never have had this problem or any other problem.

1. Started to run in my new sirio. Heated it up to 120c with a heat gun. Started it up it was having trouble idling. Had a look inside engine and noticed a big chunk broken from piston.


2. After some cursing I took out a new nova rossi that I had spare in a box. The run in process wet o.k. Ran about 750 ml of fuel with no problems. Took the back plate off to put some after run oil on the rear bearing and again in the same spot a huge chunk of piston was stuck by oil on the backplate. Strange thing is that the engine was great during the run in process. Hotest the engine got was 113c. It remained steady between 90 and 113c during the run in process.


I use the method outlined in the run in bible in international rctech offroad forum. I have always used this process with great success.

Question would these issues be due to lack of lubrication in the fuel?

Are you moving the heat gun around enough when you're heating it? It almost sounds like you over-heated one spot on both engines, but I'm just guessing here. This is an issue I've never come by before.

I was putting the heat on the top of the heatsink

they were both never taken apart prior to starting?

you werent chipping the piston from taking the backplate off?
i did this with my new alpha.

just putting it out there:sweat:

with the nova i only noticed it when I took the backplate off? Not sure if it was due to this. I did not know that you can chip the piston doing this. Can you still run a motor with a chiped piston?

No never took them apart. Where do you heat the engine? Is it on top of the heatsink?

Thats why they have a groove at the top of the back plate as the bottom of the piston goes into the top of the back plate so you must make sure the piston is at top before you take this back plate off...surely you knew this??didnt you say you have run in about 10x motors as its rule number 1 really:sneaky:
if this is not what caused it it sounds like you may have heated the head up to much..hard to say but 120c I presume is very warm for a new motor..

you should try and heat all of the engine...not just the head..only takes about 40 seconds with a heat gun:nod:

this is what it sounds like

did you pry the backplate off?

Motor will have to be at or near TDC before the backplate is taken off, If its not it can chip the bottom skirt of the piston.

I can verify that the motor was bdc so its my bad:mad:

That sucks!

Live and learn.

dont worry mate i did the same thing with my new alpha as my old sh engine you didnt have to have it at TDC

we all learn from our mistakes me especially:blush:

did they still run o.k