Seized and shattered piston arm and head

[appst8design]

I recently bought an S-Maxx to kind of get my feet wet with Nitro RC trucks. As you would guess there is not much I know about the trucks but there is a lot I'm finding out. I believe I broke it in the right way per the manual but after what happened maybe not. Last week while starting it I noticed the carburetor had a leak along the fabricated seam so I glued it shut, let it dry, and then started it back up for another run. About a full fuel tank later while using the truck it cut off and stopped dead. I was using the EZ start to try and restart it but the engine wasn't even rolling over so I knew it was a bigger problem. I haven't even run a gallon of fuel yet so this engine failure seems very premature. I'm pretty handy (or some of you may say not really after reading this post... lol) so I started to disassemble the engine and started to find bits of metal. Come to find out the piston arm had shattered and the piston was froze in the piston sleeve. So that being said could this (A) be a result of breaking it in with a busted carburetor which resulted in a lean/rich fuel air mixture resulting in engine failure. (B) me breaking it in wrong in cold temperatures. (C) the engine running at too high of a temperature. (D) something I haven't mentioned.

Any advice would be much appreciated, thanks!

 

[w bill]

Looks like it got lean the oil in the fuel does weird stuff in the cold nitro engines and cold weather is not a good combo plus you need to run it very rich i dont think that carb problem helped ethier get a new engine a test stand put a prop on it break it in then use it in the truck i prefer bench break in myself that way you can run the hell out of and not worrychalk up one for experiance!!!!!!!!!!

 

[alien13]

Shouldn't break in engines in the cold. I had a Losi 3.4 last spring that looked like that with less than ten tanks on it.

 

[appst8design]

Looks like it got lean the oil in the fuel does weird stuff in the cold nitro engines and cold weather is not a good combo plus you need to run it very rich i dont think that carb problem helped ethier get a new engine a test stand put a prop on it break it in then use it in the truck i prefer bench break in myself that way you can run the hell out of and not worrychalk up one for experiance!!!!!!!!!!

Put a prop on it? I'm guessing you mean an airplane propeller. Then build a stand to hold the engine while I do it? Explain exactly what you mean if you have time, thanks.

Shouldn't break in engines in the cold. I had a Losi 3.4 last spring that looked like that with less than ten tanks on it.

Is this a complete engine loss or should I just be able to replace the piston arm/head and piston sleeve?

 

[bergoff]

It's cheaper to buy a new engine. What engine was in it?

 

[Newb86]

The prop "propeller" is to keep air flow across the head for cooling. I have done a bench break in before using this method and the engine is still running today 7 years later with about 12-15 gallons through it. I usually follow manufacturers break in procedures though

 

[Metalhead Matt]

That engine looks like it was ran really lean. Leaks shouldn't be fixed with glue; you have to use the proper product for the job. Read up on how to seal nitro engines. The nitro tuning tips and tricks at the top of this forum explains sealing in detail. Get a new engine, seal 'er up and if it's below 50 degrees outside, wait until the weather warms up.

 

[2revo1maxx]

Well, I'm also sure it was run lean, but it probably spent too much time running way too cool as well. Winter break-ins are bad news, and any break in running under 190 degrees can wear and engine out prematurely. The sleeve has to expand for the piston to move freely up and down. Too cool and the piston is being forced up and down, breaking the rod. I would definitely get a whole new engine.
What kind of fuel were you using? It looks like it had alot of castor in it.

One more thing, Id get some lucky seven engine sealant to seal up your next mill. It 'wicks' into the crevises so you don't have to take the engine apart.

 

[appst8design]

It's cheaper to buy a new engine. What engine was in it?

Traxxas 3.3... the RTR S-Maxx

That engine looks like it was ran really lean. Leaks shouldn't be fixed with glue; you have to use the proper product for the job. Read up on how to seal nitro engines. The nitro tuning tips and tricks at the top of this forum explains sealing in detail. Get a new engine, seal 'er up and if it's below 50 degrees outside, wait until the weather warms up.

LOL... so super glue wasn't the right glue? Thanks for the tip I'll check it out.

Well, I'm also sure it was run lean, but it probably spent too much time running way too cool as well. Winter break-ins are bad news, and any break in running under 190 degrees can wear and engine out prematurely. The sleeve has to expand for the piston to move freely up and down. Too cool and the piston is being forced up and down, breaking the rod. I would definitely get a whole new engine.
What kind of fuel were you using? It looks like it had alot of castor in it.

One more thing, Id get some lucky seven engine sealant to seal up your next mill. It 'wicks' into the crevises so you don't have to take the engine apart.

Engine sealant? How is this done? Something you put in the gas? Spray in the carb? Spray in the glow plug hole? I appreciate the advice!

The prop "propeller" is to keep air flow across the head for cooling. I have done a bench break in before using this method and the engine is still running today 7 years later with about 12-15 gallons through it. I usually follow manufacturers break in procedures though

Just attach a prop to the end of the engine shaft on the new engine and then mount it to some fixture for break in?

 

[2revo1maxx]

Best thing I can do is tell you to use the search feature for engine sealing. There are write-ups all over this site and the www explaining it in superb detail.
As for the propeller thing, i would not do that on a car/truck engine, it's too much hassle. It's the way to go on an airplane engine, but on a truck? The best thing to do is search that also, it's in here. I prefer some 'heat cycles' followed by the 'traxxas' method.
BTW 3.3's are well known for their split conrods. These engines have alot of taper or 'pinch' in the piston sleeve, which makes the rod work really hard to force the piston up. That's why having the engine up to 180 + is so important. I even go through the trouble of pre-heating the engine before startup. When sealed, broken-in and tuned correctly they are pretty potent little engines.

 

[olds97_lss]

If I had a garage, I'd have a break in stand that's built for the job, but look at this to get an idea what a bench break in setup is all about:
http://www.amainhobbies.com/product...products_id/8353/n/Hudy-Engine-Break-In-Bench

I'm not 100% sure how you break-in using a stand, but there are many write ups on heat cycle break ins on this forum:
https://www.rcnitrotalk.com/forum/showpost.php?p=600523&postcount=5

Sealing:
https://www.rcnitrotalk.com/forum/showpost.php?p=726317&postcount=6

Both are found in this sticky:
https://www.rcnitrotalk.com/forum/showthread.php?t=60832

 

[2revo1maxx]

Hmmmm, now I suddenly wanna mount a prop to my new engines....lol

 

[appst8design]

If I had a garage, I'd have a break in stand that's built for the job, but look at this to get an idea what a bench break in setup is all about:
http://www.amainhobbies.com/product...products_id/8353/n/Hudy-Engine-Break-In-Bench

I'm not 100% sure how you break-in using a stand, but there are many write ups on heat cycle break ins on this forum:
https://www.rcnitrotalk.com/forum/showpost.php?p=600523&postcount=5

Sealing:
https://www.rcnitrotalk.com/forum/showpost.php?p=726317&postcount=6

Both are found in this sticky:
https://www.rcnitrotalk.com/forum/showthread.php?t=60832

That break in setup is pretty bad a**. Might try to make one that's similar that will mount next to my car without removing the gas tank and EZ start.

That engine looks like it was ran really lean. Leaks shouldn't be fixed with glue; you have to use the proper product for the job. Read up on how to seal nitro engines. The nitro tuning tips and tricks at the top of this forum explains sealing in detail. Get a new engine, seal 'er up and if it's below 50 degrees outside, wait until the weather warms up.

I'm trying to understand the reason for a new engine. I can get the piston sleeve, arm, and head for like 60 bucks. A new engine will cost around 135. Any reason for an entirely new engine?

Looks like it got lean the oil in the fuel does weird stuff in the cold nitro engines and cold weather is not a good combo plus you need to run it very rich i dont think that carb problem helped ethier get a new engine a test stand put a prop on it break it in then use it in the truck i prefer bench break in myself that way you can run the hell out of and not worrychalk up one for experiance!!!!!!!!!!

I'm trying to understand the reason for a new engine. I can get the piston sleeve, arm, and head for like 60 bucks. A new engine will cost around 135. Any reason for an entirely new engine?

 

[Metalhead Matt]

Whatever is cheaper for ya. You ought to pick up new bearings as well. Bocca makes good bearings.

 

[w bill]

Yes an airplane prop bout a 9/6 in size you can make or buy a stand talk to your hobby shop bout that it keeps it cool while breakin in buy a 4oz sullivan tank run only like a 20 percent fuel for break in my opinoin i would go with the new engine run about 1/2 a gal through it you should be brokin in when you wana run in the cold use a engine thats half shot because it will be after that hope this helps you

 

[2revo1maxx]

By the time you buy piston, sleeve, conrod, and bearings you'll be real close to the cost of a new engine on ebay. Those things can be had for 90-110 all day long, and you'll still have an extra carb, crank, head etc. The choice is yours, I'm just speaking from personal experience.

 

[appst8design]

By the time you buy piston, sleeve, conrod, and bearings you'll be real close to the cost of a new engine on ebay. Those things can be had for 90-110 all day long, and you'll still have an extra carb, crank, head etc. The choice is yours, I'm just speaking from personal experience.

You're right... I went to the hobby shop after work today and the total of the parts came to like 90 something. I can get a new engine with coupons (from buying the S-Maxx... glad I saved them) for around 110.

 

[olds97_lss]

Better to have a new one for a few bucks more than risking having a shard of metal taking out your new piston. Is always good to have a spare crank, crankcase and carb on hand anyway.

 

[Newb86]

I agree with the other guys buy a whole new engine can't beat having spare parts

 

[2revo1maxx]

I agree with the other guys buy a whole new engine can't beat having spare parts

OMG! That avatar....LMAO!!