How the hell did I snap my crank shaft?

[Wayne Drayton]

Hi,

I'm new to nitro cars and have just managed to snap my crank shaft!! Details: I bought a second hand Kyosho inferno DXII and decided to strip the GS21R engine as a way of understanding how it works and check it out. All was ok....I have done tons of research on the net so I kind of new what to look out for. Today was my second session with the car..all was ok...got through 1 tank, filled up again excellerated away and the car stalled and stopped dead. I tried to re start the engine but it wouldn't turn over.

Just got home and found the crank shaft in two halves!!

What went wrong?? I'm concerned I won't be able to get a spare crank 'cause the car's quite old. Also there is a lot of debris in the engine to be cleaned out and I pray there is no more damage to the engine (the piston looks ok).

Any comments, advice or even similar stories appreciated.

Thanks in advance.

 

[Candyman]

Well, it's not unheard of. Especially when you say you bought the ride second hand. No telling what kind of treatment it got before you got it. Wear and weakness may not be obvious even on a teardown. Considering these little engines are running at 30,000+ RPM, they take a ton of abuse and I'm surprised we don't see more of this.

 

[olds97_lss]

I've craked a crank running too rich. At least that's as much as I can figure.

It was a cold day with snow/slush on the ground and I tend to run a bit on the rich side. I had run about 5 tanks through it that day, then I changed bashing locations. The old location was relatively dry. The new location had a lot of slush around. I hit a big puddle of slush/snow at WOT and it coated the engine head. Then all the sudden I heard a weird sound and it died. The crank split in half where the cut out is below the carberator. There wasn't any water in the engine, so I'm guessing it was just because of the drastic temp change and because it was running rich.

 

[Monkey Wrench]

Wayne, you can either replace the mill outright, or, I happen to have two of those engines and can sell you the crank. That, or you can try eBay.

Kyosho no longer makes that mill (that I know) so if you decide to rebuild with a new crank and are interested, shoot me a PM and I'll see what I can do.

 

[WalawalaStore]

Hi,

I have never heard of broken crank shafts but I think the problem could be due to weather? Too cold?

The GS21 engines are sth for RTR kits, material used might not be up to standard.

Joaquim

 

[Wayne Drayton]

bust crank shaft

Thanks for your reply.

Over here in London the weather is pretty good at the moment so I don't think temperature was a factor. I have got it in my head that it was my own fault for stripping the engine down without previous experiance......nitro can have a steep learning curve!!

I didn't greese anyparts before re-constructing the engine because I thought the oil in the fuel lubricates all moving parts of the engine?

This old engine is becoming a real test but I am determined to get it going good! My concern is that if I buy a new crank that will go the same way...I really need someone more qualified to take a look at it, unfortunatly my lhs keep telling me to buy a new engine.

New engines aint cheap.....one thought I have is to maybe purchase a HPI evo rush these are a similar price to just a new engine.....any views on these cars??

 

[HeartBreak]

The key with any engine, be they new or old, is to keep them lubed, even in storage. Invest in some good After Run Oil, shouldn't cost more than a couple euros' or so. Just a few drops down the glowplug hole (remove with 8mm socket), turn the engine over a couple times (3-4 cycles, give or take), put the plug back in, and store.

I do that even if I plan on running the next day. It's cheap insurance, and helps against 'dry friction'.

Even a brand new right off the shelf engine, I do that with it, to help the internals move easier.

Plus, the after run oil will help protect the engine from corrosion, as the fuel is Hydroscopic (it attracts water like a sponge).

Hope that helps - welcome to the board!

 

[Ryan with savage]

Invest in some good After Run Oil, shouldn't cost more than a couple euros' or so.

Thankfully we still use Pounds Sterling in the UK....

 

[HeartBreak]

Ya get the drift, ryan, lol. It's cheap insurance, and makes starting a LOT easier. Not to mention, it protects your investment.

 

[WalawalaStore]

Hi,

Well, if you did not lube it properly, mostly it will cause rust, extra heat and wear to parts. The nitro for r/c already contains lubricant agent. The crank shaft is the hardest thing in the engine. Really have no idea why it got broken.

For after run oil, I will apply through the carburator, not the plug place. I use Tamiya's after run oil. Pretty good.

If you wish to replace broken parts rather than getting a new engine, please go to HPI to learn proper procedures to take it apart and rebuild:
http://www.hpiracing.com/instructions/index.htm#walkthrough

Thx

Joaquim