Topic: RB C12 locked up during running in period - HELP!
PembertonH
unregistered
posted
I had a bad experience today. Rudy & RB experts, I desperately need your help.
Recently I purchased an RB Concept C12 #1700-100 (nitro .12 size engine, 3 port side exhaust with slide carb, standard crankshaft and normal glow plug) for my new Tamiya TG10R kit.
Today I finally completed assembling this car. The engine started on the first turn. Cool! Keeping the RPMs at a proper low idle, I was allowing the engine to run-in with a rich mixture.
During the second run-in tank (after approx 120 cc of fuel total) the engine siezed up. Damn! I removed the glow plug and tried to turn the engine, but it is locked up. The crank position is approximately top-dead-center (TDC). Help!?!
Please talk me through this. What is my next step?
posted
Since your engine is still new it could be the engine locked up.
So the only thing I suggest you try first is to heat up the engine with a hair-dryer and then try and turn the flywheel by hand only!!! Don't us any tools.
If this does not free up your engine, then I suggest you take it to your LHS or Dealer and ask them for assistance. I do not think it is a very serious problem but if you are not experienced this is the best thing I can suggest to you.
posted
I fixed my "locked up engine" problem and I'm running again. Thank you Rody & RB Concept for your quick, kind assistance...!
Prior to installing this new RB C12 engine, I could turn it over by hand, feeling the tight tapered fit of the piston/sleeve and good compression as expected. However, during my second run-in tank of O'Donnell Racing Fuel, the engine seized... locked up at approximately TDC with the piston near the top of it's stroke... and the crank will not move by hand or starter box. It's stuck!
I know the machined tolerances of these nitro engines are tight fitting. I suspected uneven thermal expansion of the piston & sleeve had bound the piston at the highest point of it's stroke, at the tapered point where the parts fit the tightest. One described the problem as "cold seized the piston." Castor oil can also build up on the piston & sleeve and cause the parts to stick. I did not suspect a serious problem, but I didn't want to make the situation worse by recklessly forcing the matter.
To free the engine, Rody suggested that I heat it up with a hair dryer and then try to turn the flywheel by hand. This may work, but I felt the need to look inside the engine first... to visually inspect for cause & possible damage.
So... I removed the head, put after-run oil in the cylinder for lubrication, put a soft cloth over the cylinder sleeve & piston (to protect the parts), and with a round smooth flat plastic handle of a screw driver I gently tapped the piston down with a soft hammer until it became free. Thereafter I removed the sleeve and inspected all parts. There was no visible damage.
With the engine apart, the piston moved freely by hand through the travel of the sleeve, except for the portion near the top of it's stroke (near TDC) where the tapered fit is tightest. I cleaned the sleeve thoroughly with nitro cleaner.
Now knowing that it wasn't a serious problem, I reassembled the engine. With no glow plug, I put much after-run oil in the cylinder and tried to work it free by hand. It was still tight and sticking near TDC. Using after-run oil as lubrication, I turned the engine on the starter box (no glow plug) and ran it for several minutes. This freed it up considerably. I could now turn it by hand, feeling the tight fit as expected. Thereafter I installed the glowplug and started the engine. It ran properly. I'm happy again! I continued with my run-in procedure.
I hope that the above experience may help solve someone else's "seized engine" problem someday.
posted
Do not break in your engine with the starterbox! This will cause excessive wear. And do not try to hammer down a stuck piston, think about what would happen if the big end is at TDC... Pre-heating very tight engines with a hairdryer is a good advise and solves the problem just fine. Posts: 35 | From: Sweden | Registered: Jul 2002
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posted
if you dont turn the engine with a starter box, what should i use? thats the only way i kow how to. I'm trying to get mine started, but i'm having the same problem. its hard to turn.
Pre-heat the new engine with a hair-dryer or a heat-gun, but be careful with the last one. Then you put it on the starterbox.
The tight piston/sleeve combination is necessary to get a perfect fit between these two.
Posts: 654 | From: Holland | Registered: Jul 2002
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