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Old 02-28-2011, 11:35 PM   #1
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Default Nova S21WCS09 - Broken Conrod

Hi,

My Nova S21WCS09 (Kangaroo)'s conrod is busted after only about 4 liters of nitro through it.

I have always run my engine slightly on the rich side, with temps approximately between 95 to 110 degrees celsius.

Pictures of the parts in question is shown below. Not sure if by looking at the pictures, whether anyone can shed some light on the cause of this so that I can at least take preventive measures in future.

thanks in advance.

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Old 03-01-2011, 12:39 AM   #2
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The funny thing is that the sleeve has a lot of dark spots what gives me the idea you have runned a fuel with castor oil but the piston is compleetly blank. Or you have runned a bad fuel or you had a very tight pinch.

I have a goal to replace the rod before 5 liter of use, for sure when it had a tight pinch for a long time.
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Old 03-01-2011, 01:17 AM   #3
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The funny thing is that the sleeve has a lot of dark spots what gives me the idea you have runned a fuel with castor oil but the piston is compleetly blank. Or you have runned a bad fuel or you had a very tight pinch.

I have a goal to replace the rod before 5 liter of use, for sure when it had a tight pinch for a long time.
thanks for the inputs.

funny thing is I had ordered a r7 conrod and intended to replace it... but never got around to it.

I now have a very dirty paper weight... not worth rebuilding given that the piston/sleeve/conrod set is almost 75% of the cost of a new engine. *sigh*
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Old 03-01-2011, 02:20 AM   #4
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Be aware the crankpin had taken a huge impact and could be bend a little bit....
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Old 03-01-2011, 09:11 AM   #5
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Could it have possibly cold seized?
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Old 03-01-2011, 12:29 PM   #6
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The Piston Does Not Look Broken In No Dis Coloring At All What Kind of Fuel Did You Run I Change Are Rods When We Get Play At TDC Almost 1 Gallion Every TIme OR Close
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Old 03-01-2011, 08:18 PM   #7
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Could it have possibly cold seized?
What is "cold seized"?

When this happened, I was warming up for a qualifier. Probably into lap 3 of the warmup... coming down the straight... engine just died.

In the 1st 3 laps, engine was emitting smoke exiting corners.
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Old 03-01-2011, 08:21 PM   #8
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The Piston Does Not Look Broken In No Dis Coloring At All What Kind of Fuel Did You Run I Change Are Rods When We Get Play At TDC Almost 1 Gallion Every TIme OR Close
hmmmm...

to break in the engine, i idled it on the box for 3 tanks. then on track for a further 3 tanks, and leaning top end thereafter.

Race tuning only started about the 10th tank or so.

I was using Mecca fuel with 25% nitro content. it does not state the % of castor, but some pple who also uses it at my local track rates the castor % at approxiamtely 12%.
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Old 03-01-2011, 10:49 PM   #9
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Hmm, I would say it's the fuel quality that made it bust at that stage.
By looking at the pic you posted, I can't really tell if the piston and sleeve are damaged, but they look OK from what I can see.
If the piston DOESN'T have any major scratches down the side of it, and the sleeve has no scratches either, you are lucky and can just get a new rod.
Just make sure you completely clean out the engine of any pieces left by the busted rod so you don't completely ruin an engine!
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Old 03-01-2011, 11:03 PM   #10
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it looks like this motor has had a very hot glow plug and this could of been running rich.

you can tell by the wear on the exhaust side of the piston

the rings on the side of the piston are complete gone "groves"

i would like to see a pic of the top of the piston to see if i am right.

ps dj the bottom of the piston skirt is gone
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Old 03-01-2011, 11:14 PM   #11
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Originally Posted by sammies View Post
hmmmm...

to break in the engine, i idled it on the box for 3 tanks. then on track for a further 3 tanks, and leaning top end thereafter.

Race tuning only started about the 10th tank or so.

I was using Mecca fuel with 25% nitro content. it does not state the % of castor, but some pple who also uses it at my local track rates the castor % at approxiamtely 12%.
The worst thing you can do to a new engine is to let it idle like that during the break in process. The rod was put under enormous stress when the engine was run too cold. You must make sure you get the engine up to temperature as soon possible and maintain that temp. I would advice you do a search on heat cycling during the break-in process. When running a new engine in, more damage is done when the engine is below 80 degrees then if it was running at 130 degrees plus. After breaking in an engine, I would replace the original rod after no more then 3 litres.
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Old 03-01-2011, 11:18 PM   #12
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Yeah DJ, what pic are you looking at? That piston is total TRASH man

Just razzin you dude, but maybe you should look at getting an eye exam before that nice new capricorn shows up
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Old 03-02-2011, 12:09 AM   #13
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Quote:
Originally Posted by West03 View Post
The worst thing you can do to a new engine is to let it idle like that during the break in process. The rod was put under enormous stress when the engine was run too cold. You must make sure you get the engine up to temperature as soon possible and maintain that temp. I would advice you do a search on heat cycling during the break-in process. When running a new engine in, more damage is done when the engine is below 80 degrees then if it was running at 130 degrees plus. After breaking in an engine, I would replace the original rod after no more then 3 litres.
I must of got of lucky then ... but I did heat up my engine during the first 25 tanks prior to break-in ...
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Old 03-02-2011, 03:52 AM   #14
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Quote:
Originally Posted by The_Keeper View Post
it looks like this motor has had a very hot glow plug and this could of been running rich.

you can tell by the wear on the exhaust side of the piston

the rings on the side of the piston are complete gone "groves"

i would like to see a pic of the top of the piston to see if i am right.

ps dj the bottom of the piston skirt is gone
hmmm.. the glow plug i used was a nova C8TGF.

More pictures of the piston below.





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Old 03-02-2011, 03:57 AM   #15
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Quote:
Originally Posted by West03 View Post
The worst thing you can do to a new engine is to let it idle like that during the break in process. The rod was put under enormous stress when the engine was run too cold. You must make sure you get the engine up to temperature as soon possible and maintain that temp. I would advice you do a search on heat cycling during the break-in process. When running a new engine in, more damage is done when the engine is below 80 degrees then if it was running at 130 degrees plus. After breaking in an engine, I would replace the original rod after no more then 3 litres.
When idling, temps were between 85 to 90. I try to keep it within that range. I do know the importance of getting the engine up to temp asap. But admittedly, am quite new to all this. I try to read what I can and then apply it.

Obviously have not been reading enough and something obviously gone way wrong some where.

the conrod that broke was the original conrod (same used throughout the breakin process). so i guess lesson learnt. expensive lesson.
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