Sent my os18 back to the shop. The problem was no matter how I tuned it, it would get up over 280 real quick. Sent it back to OS, and they sent me a new replacement. Guess what, ran the truck 4 turn out on the high end with 20%, and the thing starts popping. Pull it in, and now Im pushing close to 300 deg. What the #*&@.
Ive sealed all possible air leak areas with leak stop, and it just wont cooperate.
HELP

The problem may not be the engine but the truck. Make sure you go over everything on the truck from fuel line to drive train as even something that could seem minor could be the cause of overheating. Gearing should also not be overlooked. How is it geared, what vehicle is it in and what kind of fuel / glow plug are you using?. I have one of these in my Revo and 220 is normal for me geared low for torque with the close ratio gears. I also run the 40 series tires on it with high traction.
I run the McCoy MC8 plug and 25 % nitro.

Inferno, thanks for the advise.
The gearing in my revo is stock, and Im using the plug that comes with the motor. Ive stepped down to Odonnels 20 % with this new motor. (only 20 has been run thru it so far.)
I played with it a little last night, and got the temp to come down on it, but Im running close to 5 turns out on the high speed needle.

I did notice that it was a little difficult to get fuel to flow thru it, I pulled the line off the muffler, and tried blowing thru it while trying to start it. Damn near mad myself dizzy trying to get fuel to flow. Any thoughts on that?

Man that sounds weird.What are the temps outside?

It could be your truck, you have to make sure everything is free of debris and everything is moving freely.

Take the spur gear off and spin the the back wheels to see if the tranny is smooth.This won't make much of a difference but it could help.

How many turns out have you got the LSN?

Sean

I run a TNX with the similar engine. I also initially had some overheating issues but was able to overcome them.

I was running 240 degrees until I opened up a hole in the windshield and opened up the side window. Not sure if you have done this? My temps dropped instantly to 199 degrees with the same settings!

Seems the OS 18 likes cool air on the head.............maybe why the TNX pro comes with a larger head? Mine with the stock head runs 100% now

Hope this helps

Lenny

Hmm fuel flow from the tank can also be an issue, check to make sure everything is fine in the tank. A clogged tank filter can play havok with settings.

Guess what guys. After going thru everything, I found that the main culprit was a combination of the fuel, and the fuel line. I WAS using odonnels 30%, and after doing some research, and talking to a couple of hobby shops. I found out that Odonnels has a tendency to gum up in the carb, and also break down the silicon inside the fuel line. As far as cooling, the temps outside have been in the low 80's, and I was having the overheating problems with the body off. But I do cut holes in the body for cooling. Im also running an oversized air filter. Hopefully Ive solve the problem. SO BEWARE OF ODONNELS FUEL
I will keep you all updated as to how the truck is running. Thanks for all your input.

Also checked for any mechanical binding, and everything was fine. Right now because Im breaking A NEW MOTOR in (OS just replaced my first 18TM) Im running it hella rich. Im a little over 4 turns out on the hsn. I also switched over to lightning fuel. When I was running my stock 2.5, I was running top fuel 33%, and Im thinking about going back to that.

Ok, update on my current situation with the os18. Called OS, and they said that I cannot use 30% to break in. HMMMMM wasnt a problem with the last motor. Anyhow, does anyone have any suggestions as to a good 20% with a high oil content (around 12-15%) ?

Never had a problem with odonnels fuel..
its possible that with the 30% you were detonating causing the engine to overheat.. try adding a .1 head shim

Sidewinder Race (20%/12%) - Awesome!

definition of detonate, and what does the shim do?

sidewinder also makes a fuel called "backyard basher", its a 20% nitro with 16% oil.. this makes your engine last real long

When the fuel reaches the combustion chamber and then detonates (explodes could be another way of saying it) from the glow plug.The shim will just lower compression.In a way i can see this helping with the engine temps.

Sean

You might try Trinity Monster Horsepower 20%--it's got a high oil content and although messy (lots of oil will drain after running), it keeps your engine cool and running forever.