New OS .18TM running hot- possible air leak

[fisureman]

Just installed a new OS .18TM I bought on craigslist for a new build. All new fuel lines and tank tie wrapped at all points. Engine running hot on break in settings, shutting it down when it reaches 260. No smoke in the tank as normal and it seems like it was having trouble with pushing fuel initially. Where should I be starting to look?

 

[mikelh]

Just installed a new OS .18TM I bought on craigslist for a new build. All new fuel lines and tank tie wrapped at all points. Engine running hot on break in settings, shutting it down when it reaches 260. No smoke in the tank as normal and it seems like it was having trouble with pushing fuel initially. Where should I be starting to look?

I would make sure it is blubbering rich spitting fuel out of exhaust and gradually run it for longer and longer times. I would let it cool completely between runs with piston close to BDC. A new engine should be tight and prone to heating up. Of course if you suspect any air leaks or fuel blockages fix them first.

 

[cbaker65]

Exactly... ,force an engine to work harder by nearly flooding an engine to death on top of the tight pinch & compression
that it already has to deal with!...

If you lean the engine out a little each tank .you should find that the engine should start to actually run cooler ,also ,you
need to consider that theres no airflow over the head ,try putting a small fan to blow some air as you break it in!...

An the real trick to a longevity of a nitro engine is to put the piston dowm out of the sleeve when it
is cooling down!
Mark the flywheel with the piston a BDC ,when you shut it down after its ran ,rotate flywheel to the mark
persay at the direction toward the carb.

 

[mikelh]

Just installed a new OS .18TM I bought on craigslist for a new build. All new fuel lines and tank tie wrapped at all points. Engine running hot on break in settings, shutting it down when it reaches 260. No smoke in the tank as normal and it seems like it was having trouble with pushing fuel initially. Where should I be starting to look?

If your engine is overheating at idle it means the engine is to lean or that it is just new and needs some heat cycles. A nitro engine doesn't need air movement to cool it at idle. If that were so every engine would overheat at idle instead of cool down at idle. BDC= bottom dead center, as I previously stated make sure all your nitro engines are left BDC after use. All my OS engines have been awesome. Good luck and have fun with it!

 

[fisureman]

Thanks for the quick replie gentlemen. I always return it to BDC after a heat cycle during break-in and when relatively new. It did start to cool down a bit after the first tank, but it was running up quick initially. I checked my lines and didnt detect a leak and I am inclined to think it shouldnt have a leak in the motor being new, however it had sat around for while before first fire, so I wasn't sure if maybe the gaskets went bad or something. Good to hear you guys experienced similar issues with a really tight new motor.
Thanks again,
Ian

If your engine is overheating at idle it means the engine is to lean or that it is just new and needs some heat cycles. A nitro engine doesn't need air movement to cool it at idle. If that were so every engine would overheat at idle instead of cool down at idle. BDC= bottom dead center, as I previously stated make sure all your nitro engines are left BDC after use. All my OS engines have been awesome. Good luck and have fun with it!

Picked up a OS .21TM as well, just working through the build pieces now and will be breaking that sucker in shortly as well. Thanks!

 

[Certified Mike]

I would run it on the rich side, make sure you ARE getting smoke out of the exhaust. It indicates that the fuel, and therefore the lubricant and cooling is getting thru Your motor properly. If It's in a hot environment where you're breaking it in or where airflow is restricted over the head, you can always use a fan to keep the temps down but 260 isn't terrible depending on ambient temps. Certainly a tight, New motor could tend to run a little warm. You may also benefit by warming the cylinder head prior to running with a heat gun or similar. Just some thoughts. Good luck!!!

Btw, I wouldn't run it too rich as explained above.

Also should try the pinch test as a good possible answer, assuming that you are sure of no leaks as it sounds.
Quoted by @GAJ :

The pinch test:

Pinch the fuel line closed at about 3 cm from the carb. The engine should run for about 4 to 6 seconds, rev up then die.
If the engine dies immediately, or the RPM's do not rise, the LSN is too lean.
The starting point should always be the Idle Stop, the throttle should be open approximately 1mm at the stop.

 

[fisureman]

I have blown up motors and broke in a few in my journey to learn how to tune. I am not saying I'm an expert, but I definitely am no slouch. Hadn't encountered the issue before with a new motor, but I will say that brand new OS was considerably tighter than any 3.3 I have had before. From the sound of it initially, it seemed and sounded like it was running lean, then miraculously got better. Definitely running very rich now and just adjusted the high speed a quarter turn after the first tank with a slight temp improvement. Will continue to play with it and see what happens avoiding any damagin temps. I was just downstairs and re-checked the lines which are tight as a drum. If the issue persists, the only other think I could think of would be something on the engine sucking air. I didnt rule this out, but its definitely not where I start with a brand new engine.

 

[Certified Mike]

Totally agreed that you shouldn't have a leak with a brand new engine. It sounds like it might have just been a lil extra tight, which isn't really a bad thing. I think you've got this under control by what you're saying. If there's anything we can do to help, just ask. Please post with your results. Good luck!

Oh, just as a second thought, make sure the carb is tight.... I have heard of a LOT of motors shipped with a loose carb for easy of adjustment during install.

 

[fisureman]

Good one, I will definitely check the pinch bolt and let you guys know how I make out. Really appreciate this forum so far..really solid responses! Thanks again!

 

[Certified Mike]

Any time! That's what we do here. Your thanks makes it all worth it. Your results help to make us all a little wiser. Thanks for letting us know how it is going. Again, good luck!

 

[fisureman]

Well...I'm incredibly embarrassed to say I found the air leak. Turns out the high speed needle was loose the whole time. Ran it tonight and she's purring like a kitten and cooling at idle as she should. I don't think I did any damage as I was shutting it down before she got too hot. She's ready for the remainder of the break-in and full time service thankfully.

Check it out

 

[mikelh]

Nice! I'm sure its fine. Thanks for sharing so someone else might gain from your experience.

 

[cbaker65]

Great!...

Keep tabs on your cylinder head screws as well ,I've had some that worked loose before!...
You will enjoy the power of that OS!...

OH ,that's a great lookin truck I might add!..

 

[fisureman]

Thanks so much! I defnitely checked her over after that mistake. can't wait to get her outside this weekend!

 

[Certified Mike]

Nice looking ride for sure! Glad,you got it all sorted! Let the smoke shows begin!!!

 

[ninnon]

Glad to Know you got it fixed, Any more problems and you know where to come

 

[fisureman]

Great group... really appreciate the support!

 

[Tape]

is the OS .18TM (stronger/more HP) than the Traxxas 3.3?

 

[cbaker65]

is the OS .18TM (stronger/more HP) than the Traxxas 3.3?

I've never owned the OS 18 TM version ,or HPI an 3.3 , however ,I do own the OS 18 cvr an what I've read on
forums for the pass 10 years ,the Os 18 cvr smokes them all ,hands down!

Could be the reason why the cvr 18 isn't out of existence ,its been Os's primary hot seller for the past 25 years
that I know of!....

 

[Certified Mike]

I love that I can still but whatever I need for my cvr! I can wait to fire that sucker!