New out of box Os .21 running hot

[Svndustdude]

Ok, hopefully someone can shed a little light for me. I have a 4309 revo with 3.3, long story short broke Conrod . I ended up purchasing a new os .21 tm ( which was basically a direct drop in) got it in and all bolted up with new clutch, clutch bell , fuel lines, fuel filter, tank, lc3 plug, 20% sidewinder fuel

I took the truck out today to break the motor in. Weather was kind of mild at around 65 if this even matters. I preheated the block up to about 160*, primed the fuel, took it outside and it fired right up on 1st hit. AWESOME! The truck pretty much will take off on its own if I don't hold the brake and the temps jumped up to 260 ish with the quickness so I immediately richened it up a half turn. From reading about break in procedures most say 190 to 220. So I was worried

So I take it out and run at 1/4 throttle for a tank and bring it in and let it cool down for 15mins. Try to start it up and nothing. Keep trying and finally get it to fire but have to give it gas.... For this run i put it back to factory settings and give 1/2 throttle. Temps still too high for my liking but what ever. It's pig rich and fuel is all over the rear control arm and lots of smoke.

As more tanks go by its just more of the same. I incorporated some of os breakin procedure as well by leaning hsn 30* or 1 hr increments per tank. Still dumb hot into 300's and spewing raw fuel.

Btw factory settings were all needles flush..... And guy I bought this expensive pita from at the Lhs told me not to worry about sealing it up because o.s. is top of the line.

Does anyone have any ideas about what's going on. Hopefully is not toast already . Thanks

 

[chickenman242]

I had the same probs with mine I had to richen up the lsn and hsn nearly a turn on each to get it down to 220f
Maybe it has something to do with your location and humidity

 

[Svndustdude]

Weird. Don't understand because plug is wet and its spitting raw fuel. I'll give it a try tho

 

[hotrodrob]

Possible air leak,check all fuel lines,test fuel tank,and tighten up the exaust in all locations

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[Svndustdude]

Everything is new but anythings possible I guess. It has spring mounted header with gasket too.

 

[Svndustdude]

Turns out I have an air leak at the carb and pinch bolt. Should have checked it before running. Just cost me a new motor I think. When I spin the fly wheel at close to tdc I can hear a ting noise. If I rock the flywheel back and forth it will keep making the noise . Smh is this normal? I can see the piston still moving up and down.

 

[synnyzter]

Turns out I have an air leak at the carb and pinch bolt. Should have checked it before running. Just cost me a new motor I think. When I spin the fly wheel at close to tdc I can hear a ting noise. If I rock the flywheel back and forth it will keep making the noise . Smh is this normal? I can see the piston still moving up and down.

How easy is it to turn the flywheel to tdc? A fresh motor not even broken in you really should barely be able to by just a finger, it should be difficult as it should be extremely tight and yeah it would make noise from the friction at that point as the sleeve is slightly cone shaped toward the top where it is at its tightest. Depends on the sound. If it's a high pitched ping you may want to see if there is any debris in the cylinder, but id take the whole thing apart and inspect it.

If you are spinning it without the plug in it should make a funny like popping sound at tdc, but no pings! Doesn't sound good mate.

BTW RTR does not really mean ready to run, and no 2 engines are the same. Always the first thing you should do as I do, is give everything a once over to make sure everything is as it should be before even thinking of running it. I've seen so many brand new trannies and engines fail because the factory jacked them up and threw them in a box.

 

[Extreme RC Mods]

I would check the clutch as it sounds like it may be engaging too soon by your description. If that's not the problem then it may be a lean LSN causing it to high idle and want to drive off, this will also cause the temp to rise and start running hot as it should be slightly cooling at idle.

 

[2revo1maxx]

By fixing the the pinch bolt you may have fixed the high idle. If it's 65° degrees out I'd partially cover the head and run it pig rich for a few more tanks. You want 200+ degrees and rich for a proper break-in.
Before you do anything take the plug out and turn it by hand, it should be tight at top dead center.

 

[Svndustdude]

Everything seems tight. I did notice where the back plate is, the crank is what makes the noise when I get close to tdc. When I rock the flywheel back and forth it moves in and out at the "ping". I'm hoping it does that because there is no one way bearing or ez start installed. I'm gunna hit up the autoparts store and get some copper rtv today and seal it up and give it a try. Thanks for the input !

 

[bgbdwlf2500]

Definitely seal it before you do anymore with it. An air leak would cause all of your symptoms except the ping. Not sure what that is

We fried my brothers 3.3 because it wasn't sealed. It ran 400 degrees no matter where the needles were

 

[Svndustdude]

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All sealed and playing the waiting game now. Says it takes 24hrs for the rtv to cure. Trying to be patient lol. When I took the back plate off I didn't see any visible wear or cracks or discoloration, so fingers crossed I'm hoping all issues will be resolved and some fun will resume lol

 

[synnyzter]

Good luck man, hope your engine survived! I know how frustrating it can be. I just fried a newly rebuild 3.3 a few days ago =( Let us know what happens!

 

[Svndustdude]

Ok, did one last leak test and my problem spots were fixed. Put the truck back together , filled the tank up and hit the streets. I knew it was running dumb rich to start with so I ditched the Hsn setting that was set when I pulled it out of the box( 3 1/2 turns out) and went 2 1/2 turns out and found a little success in it. I also used a paper clip to set the gap for the idle on the slide carb. To my disbelief it fired right up without a problem with no run always for high idle. However as the temps started coming up the truck would roll on by itself with no throttle. I took the advice and richened the lsn and the went away momentarily. I ran about 4 more tanks through it and slowly started leaning the hsn back while keeping an eye on the temps. (Never got above 250) decided to not lean it out too much because I would like to get more tanks on it before I really try to get the tuning perfect. I set the lsn per the " pinch test" and got that somewhat dialed in for now. Stays idling and pulls wheelies from a stand still. But the darn thing still wants to go on its marry way at idle... I'm going to tear the truck back down this week and search for more leaks. I'm just stoked that its running better temps and atleast idling now. This is what the hobby is all about, troubleshooting and getting stuff figured out but man can it be a pain sometimes . Thanks for the insight!

 

[srusinek]

Congrats on making progress with your new engine. I'm a big fan of sealing an engine but only if it has problems like you're describing. I also have two OS engines in my fleet(.12 CVRX and .18 CVRX) and I've never sealed them. I would look at your clutch because that would cause it to take off on you.

 

[Svndustdude]

Yeah I heard that o.s. makes a great engine that is user friendly. Pretty much why I went with the .21 . I am running a oem traxxas 3.3 clutch with an mip spring. It was still pretty much new. Like 3 tanks on it before I swapped to a crappy 3 shoe that uses stock spring.... That was the set up I was using when I broke the connecting rod on the 3.3. I will get it figured out though, just a couple steps closer now haha

 

[chickenman242]

i found i my 21tm once i got it broke in i was always chasing a tune,what i did was remove the needles plug the exhaust and put a bit of green slime on the orings of the needles and reset everything and started again,much easier to tune and temps were better.maybe have a look at your needles as an oring may be pinched or torn

 

[synnyzter]

did you try to idle it down a bit more? Its either idling too high or like dude said it could be the clutch. Sounds like your almost there, it can be a serious pain finding the right combo on your needles. Just remember always start with a 1mm idle gap (typically this rule of thumb), adjust the HSN, and set the LSN last which will help control idle.

 

[Svndustdude]

Yep , set idle 1 mm then pulled that back a little too to try and get it to quit walking. Leaned hsn back slowly and got it pretty modest, not too crazy. Then messed with the lsn. I will get a new clutch soon but I will def take the motor back out and check for leaks again as well as check the needles and get back to y'all with hopefully some good results.

 

[synnyzter]

I prefer 2 shoe clutches with the wrap around spring, they give you more surface contact and tend to last longer and I feel the single spring is 2 less things to wear out or go wrong lol. If you have 3 shoe this would require a new flywheel however but its cheap and a good investment in my opinion. I always do this right away if I have a 3 shoe setup. You can even turn the 2 shoes around which causes the shoes to engage harder if you want... I'm just a fan of options =)