Broken plug during break in, normal ?

[chrisexv6]

Technically still breaking in my STS 28. Ran it for 3/4 of a tank today, it was running fine. Temps in the 220s, the idle is still a little funky but thats it. I was futzing with the idle a little (trying to get it to a lower RPM), but the engine would start "dipping" down after a high speed run, and stall. Raised the idle a little bit and that stopped too.

Hit the end of the tank, and it died out. Ran out of fuel, no problemo. Pulled the plug like I always do (to make sure the piston is at BDC) and noted the plug coil was snapped. Not really distorted, as the piece that was welded to the plug casing was still flat. It doesn't seem like any piece separated from the plug, I checked the sleeve and piston really quickly and there was no sign of any foreign objects. Obviously I will tear the engine down to clean it.

My question is, could this be normal? Its an MC59 plug, and I've put probably a little over a quart on the engine and plug. This is the same plug thats been in the engine since the beginning of my heat cycle break-in (although I'm past the heat cycle, and onto tuning).

Just wondering if this might be a sign of things to come, or if it could just be normal wear and tear on the plug.

Thanks.

-Chris

 

[griemar]

fouling a plug during break in is nothing to worry about, it happens ALLOT. I'd just make 100% sure that no pieces went into the engine before you run again. 1 tiny piece can ruin your day real quick. Even the pro's will foul a plug during break in.

 

[chrisexv6]

Awesome, I can feel some relief

Definitely going to tear down the engine and clean it out. Happy that its running so well, at least for now!

 

[hpinitromt]

totally normal to foul plugs during break in, you should always change to a new plug after break in anyways

 

[chrisexv6]

Yeah I was wondering exactly when break-in would be done, doing the heat cycle. Looks like Ill be switching now!!

A cooler MC8 plug is ready to go in. Gonna order spares quickly!

-Chris

 

[griemar]

Yeah I was wondering exactly when break-in would be done, doing the heat cycle. Looks like Ill be switching now!!

A cooler MC8 plug is ready to go in. Gonna order spares quickly!

-Chris

Dont rush a break in, a typical break in you'll run between 5 to 8 tanks before you can start laying on the throttle for extended times. Always keep extra plugs and depending on your climate, keep both medium and hot plugs available. It's amazing how much difference a plug can make when the weather changes.

 

[chrisexv6]

Dont rush a break in, a typical break in you'll run between 5 to 8 tanks before you can start laying on the throttle for extended times. Always keep extra plugs and depending on your climate, keep both medium and hot plugs available. It's amazing how much difference a plug can make when the weather changes.

Chart I found on the net explaining the McCoy temp ratings says that I should actually only ever be running MC8 (bottom of this page: http://www.outlawrc.com/glowplugs.htm) I never run in weather under 60 degrees (too cold for me ), but I could understand having the hot plug during break in.

While I havent gone thru 5-8 FULL tanks, I've been thru about 10-15 quarter and/or half tanks (I was trying to minimize the amount of fuel wasted during the heat cycle break-in 2, 3, and 5 minute runs). I'm sure it all adds up to 5-8 full tanks I'm hitting full throttle on the engine at this point, but only for very very short periods of time, trying to tune the HSN before I start with the LSN. Temps are staying well within range and there is a good smoke trail at all speeds. Like I said, just a funky idle that fluctuates like water in 100 knot winds!

-Chris

 

[chrisexv6]

OK, tore down the engine as best I could and flushed it out. Poured some denatured alcohol into the crankcase and blew it out with compressed air, did that 3 times. Also blew compressed air thru the carb inlet out the back of the engine, and thru the sleeve.

The problem is that I can't get the conrod off the crank. It seems like a common issue with the STS motors....the conrod bushing is TIGHT against the crank. I didnt want to risk breaking the conrod, bushing or crank pin so I havent pulled it off.

Think I'm good to go? Should I flush it all over again to be sure? Nothing came out during the flushing, and everything spins freely. I could swear I felt one spot that the crank may have "caught" a little, but it never happened again. My worry is that any part of the plug that might have gotten into the engine is somehow hidden in/behind the bearing, waiting to destroy it.

Any tips?

Thanks.

-Chris

 

[griemar]

OK, tore down the engine as best I could and flushed it out. Poured some denatured alcohol into the crankcase and blew it out with compressed air, did that 3 times. Also blew compressed air thru the carb inlet out the back of the engine, and thru the sleeve.

The problem is that I can't get the conrod off the crank. It seems like a common issue with the STS motors....the conrod bushing is TIGHT against the crank. I didnt want to risk breaking the conrod, bushing or crank pin so I havent pulled it off.

Think I'm good to go? Should I flush it all over again to be sure? Nothing came out during the flushing, and everything spins freely. I could swear I felt one spot that the crank may have "caught" a little, but it never happened again. My worry is that any part of the plug that might have gotten into the engine is somehow hidden in/behind the bearing, waiting to destroy it.

Any tips?

Thanks.

-Chris

If you flushed out both the top and bottom of the engine then I personally would go ahead and give it a try. You did make sure to move the piston all through it's cycle when flushing right? Just to make sure you flushed as much as possible. Good luck and let us know how it turns out.

 

[chrisexv6]

Yeah, I kept as much alcohol in as I could while slowly turning the piston thru its travel. Did that with and without the sleeve installed, also cotton swabbed down the innards (including where the sleeve goes), etc. I'm always thorough with the engine cleaning I guess I was just a little paranoid something might happen.

For now I might just run it for a few minutes and check inside it again to see if I see anything I dont like.

BTW, FWIW ODonnells fuel is the shiznit! There was a coating of oil ALL OVER the inside of the engine. Awesome stuff, I've never seen a coating like that before, running Monster HP.

-Chris

 

[griemar]

Yeah, I kept as much alcohol in as I could while slowly turning the piston thru its travel. Did that with and without the sleeve installed, also cotton swabbed down the innards (including where the sleeve goes), etc. I'm always thorough with the engine cleaning I guess I was just a little paranoid something might happen.

For now I might just run it for a few minutes and check inside it again to see if I see anything I dont like.

BTW, FWIW ODonnells fuel is the shiznit! There was a coating of oil ALL OVER the inside of the engine. Awesome stuff, I've never seen a coating like that before, running Monster HP.

-Chris

Sounds like a plan and thanks for the fuel info. It's good to know that it's actually doing it's job unlike other brands. *cough*Traxxas*cough*

 

[chrisexv6]

I jumped on the Traxxas bandwagon when I got my Tmaxx. Bought their fuel and everything, broke in per the DVD, etc. The TR(ash)X 2.5 NEVER ran well for me. Carb end caps stripped and fell out, etc. Traxxas replaced the engine twice, I finally got one that ran OK and the air filter fell off and toasted it. That Tmaxx was nothing but bad luck for me!!

My Savage has been much more successful.

 

[MrClean]

Sounds like a plan and thanks for the fuel info. It's good to know that it's actually doing it's job unlike other brands. *cough*Traxxas*cough*

Sorry, not trying to hijack the thread, but I switched from Traxxas fuel to O'Donnels and I can't believe how much easier it was to tune my engine. I had it running great in less than a tank full. I probably spent a few tanks trying to get it to run 'good' with the Traxxas brand.