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.

http://i307.photobucket.com/albums/n...3-01133309.jpg

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*

Be aware the crankpin had taken a huge impact and could be bend a little bit....

Could it have possibly cold seized?

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

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.

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%.

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!

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

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.

Yeah DJ, what pic are you looking at? That piston is total TRASH man :D

Just razzin you dude, but maybe you should look at getting an eye exam before that nice new capricorn shows up :D

I must of got of lucky then ... but I did heat up my engine during the first 25 tanks prior to break-in ...

hmmm.. the glow plug i used was a nova C8TGF.

More pictures of the piston below.

http://i307.photobucket.com/albums/n...-02_183622.jpg

http://i307.photobucket.com/albums/n...-02_183555.jpg

http://i307.photobucket.com/albums/n...-02_183447.jpg

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.

hahahaha sorry, I didnt tilt my head! Looked somewhat symmetrical from how I was looking at it :lol::lol::lol:
Once I actually LOOKED at it, now I can see it's totalled!!

Don't feel bad, I broke the crank pin off my Kangaroo:D with about 1.5 gallons thru it. ouch!!!

guys, you have to pull down your new out of the box engines. i have sen so many have tight piston pins. this doesnt allow the piston to rock freely, and signs of damage can happen real quick. this wears the piston on the skirts, and the top grooves, and drags down the liner, then back up. is definately something to look at in future.

Hi Patton... thank you for the advice.

by piston pin, you are referring to the wrist pin where the conrod attaches to the piston?

If the wrist pin is indeed tight, what does one do to rectify it? is the only way to change out the wrist pin?

That's what I was thinking too.
The only thing I see in "fixing" this problem would be to check what the actual diameter of the pin is, and what the diameter of the piston-pin side of the rod is.
Even if you do find the pin to be too large, or the rod to be too tight, how can you enlarge/reduce the two without going too far?
Good to point out, hard to fix IMO.

if it is tight, i would contact the retailer where purchased, i have seen maybe 4 pins tight from nova based engines in the last year. one of them badly wore the piston in about 1.5 lts of fuel. if retailer wont do anything, i would try a new wrist pin. if that one is tight, i have some very fine bits for light polishing work. i would polish the piston very carefully and only to make it feel looser that the piston will rock in your hand if tilting the rod from side to side.

but first contact the seller before anything is done. give them the choice to replace parts, or the engine.