k I just put a brand spanking new CV-X .15 In my nitro 4-tec, lots of compression, but I had a fuel delivery probelm, and may have been a little lean on break in, stil has lots of, not theres almost no compression, If i take the glow plug out and put it back in, i have lots of compression and the motor runs good, than when it shuts off, i have no compression, take the glowplug out put it back in, i have compression again.... Could it be the glowplug gasket, yeah i know just go buy a new glowplug with gasket but the hobby shop is 20+ Miles away and i want to go driving soon.... I've checked the head, back plate, and exhaust for tightness.... I am scared to death that i damaged my new little motor

Sounds like the glow plug gasket....that would be the easiest fix.

What your saying does not make a lot of sense, unless the glow plug is getting loose and you end up tightening it, then I cant see what your describing making any sense.


What I would like to know is why you are thinking the engine is dropping in compression?

You say "I have no compression"

What are you seeing that gives you this idea?

Once we get a better picture of what is happening we will be able to better assist you

Okay i just installed a better glow plug gasket and it's still doing what it was doing before.... And closer analyzed it, let me clarify... When the motor starts and gets to operating temp, as soon as the enging starts to get warm (water starts to boil off slowly) It dies and has very little compression like a worn motor. As soon as it cools down, it has plenty of compression like normal, start it up, rock solid idle, drive it around for a minute or two to warm it up bring it in, and it stalls and wont start back up again no matter what, as soon as it cools off it starts on the first pull and has lots of compression, forget removing and reinstalling the glow plug i was wrong, the plug is tight and sealing, as soon as the motor heats up, it wont start and has little compression, it only has like 5 tanks on it, it's been blowing smoke the whole time and hasnt over heated but it should have been running it a little richer during break in, i wasnt hard on it and it didnt run too lean, it just should have been richer, i am ready to send it back to OS....anyone got any ideas, i double checked head bolts, backplate bolts, carb, pipe, everything, as soon as it heats up i lose compression, when it cools I have compression

I would break the engine open and inspect the internals. Have not heard or experienced this problem before. One thing though is that you mentioned "stalls and wont start back up again". Wonder if it is overheating. Have you tried richening the setting a little.

I would suggest sending it back...Its almost like the parts are expanding in the heat and allowing leaks and then when it cools off everything tightens back up. Could just be a defect. I've never had this problem. My 2 cents.

It sure sounds like a new piston and liner are in your future.
You may try running it richer, and/or with less nitro, and see if it helps.
(In case it's just overheating, due to "too lean" or "too much nitro", that is)
You may want to check all bolts for tightness, too.

I agree with hoodie..
sounds like its expanding.. and a hole opens up and lets everything loose..
must be a TINY hole in the engine structure..
it happens with cars.. you can hear it go BANG BANG.. but no power!
my friend has one of those cars.. they sound powerful but all power disapears thru hole!
my half a cent!
-ram

No no it's making gobs of power, i'm toasting tires, but as soon as it heats up, it loses power a little, and it stalls, when i try to restart it it has no compression on the pull starter.... I am NOT going to tear the motor apart yet, it's only 6 days old !! And I am running it at about 230 degrees by the way, i monitor it so i know for sure it's not overheating....

I am NOT going to tear the motor apart yet, it's only 6 days old !!

I would send it back. Why trouble yourself with what appears to be a defective engine? You've tried all of the other things so make the call to the company you bought it from and get a return on it.

Good Luck!

You describe gobs of power and what you feel is good compression when you start the motor.
Later after it warms up it looses compression and wont restart, later it starts back up.

I suggest you grab a temp gauge and start over on your needle settings according to the manual.
I say this because what you describe is a flame out or in other words over heating.

Basically the engine starts and runs great, after running it a while the engine acts erractic and then just quits...wont restart.
Once you give it time to cool it cranks right back up.
The reason this occurs is because the temp is getting too hot and the sleeve expands beyond its max point. The combustion chamber can no longer stay compressed. As the sleeve cools and shrinks it again can maintain the chamber.
Keep in mind that every time this occurs you are killing your engine.

There are quite a few issues that can cause this, you need to isolate the engine by checking the fuel lines, tank , Fuel Etc.

If you can isolate the problem to the engine and have the needles set correctly etc and still having the problem, you have either destroyed the piston and sleeve or your engine is defective. In either case I would send it in to be checked out.

Again, I suggest you invest in a temp gauge as the spit test and water droplets on the head do not work as you are seeing.

What was your fuel problem during break in?

What are you using to temp?


Dbow

I agree with crash, I wouldnt tear it down.

They can void the warranty if they know you got in it, and trust me just about anyone can tell a motor has been gotten into.
Besides you are not going to be able to see anything in the inside anyway. If the piston and sleeve are sized incorectly I dont think it will register on your eyeball.


Thats also another reason why its not a good idea to knock a stuck piston out of a sleeve or pry it out with a screw driver and the flywheel. Every move you make like this leaves finger prints all over the engine. I should rather say scratches, gouges and such in the sleeve.

Dbow

well at the hobby track i was using a buddys temp gun, at the plug it was roughly 230 degrees, using the water drop test when it starts losing power, it slowly boils away (about 5 seconds).... it's actually 1/4 turn richer than what the book says for break in, and theres plenty of smoke, so i know it's not overheating, when it loses compression and power it's around 230-240 degrees.... I dont want to pull the motor down, I was hesitant about checking the tightness on the bolts, i didnt want to scratch them, and look "Tooled" I think I am going to send the motor back to OS and see what happens.... I will priority it over there and they said i can have it or a new one back within 10 days of them recieving mine.... I talked to the OS Tech Support Guy on the phone, he said a bearing could be leaking, or an imperfection in the case somewhere could be causing it to expand when hot.... He said send it back for a replacement, but if they find ANYTHING that could have been my fault, they wont honor the warranty....

I have to send the motor back with a letter of what's going on, any suggestions ?? lol

Oh yeah i'm using Trinity Power blend 20%, i was going to get the break in blend fuel, but they didnt have any left so i picked up a qt of the trinity, I now hear it has a low oil content, anybody have any idea on a fuel that i can use, i heard that trinity was the best fuel, but i want one with higher oil content....

Suggestions? Yeah... hope they don't see where you said you ran it
with a fuel delivery problem, and with the incorrect fuel, on its breakin runs

Hopefully, they'll simply replace it, without problems.
It does really sound like the initial run-in was too lean, (therefore, hot) however.

Incorrect Fuel ?? I was un aware their could be an incorrect fuel, perhaps you would like to tell me the proper fuel =) If you mean the difference between break in blend and power blend, the hobby guy said they were about the same anyways....

Hey cruz,

send in the motor and dont worry about the fuel, I dont think you did anything wrong so send it in and forget about it.

As for which fuel is the best, its all in personal choice. I like Wildcat but thats just me. Any fuel will work, just make sure it has good oil content. I use 20% Nitro 18% oil.

Goodluck and let us know what happens with the motor


Dbow

i pulled the motor out tonight took off the mounts, took off the exhaust and carb, glowplug, i put some fuel in any entry point and flushed it out throughly with clean fresh fuel.... When it dried i used some after run oil in it i made sure the carb was clean and properly set.... Packed it up in original packing and wrote the letter and sent it off.... I couldnt find the instruction manual, and i didnt put the glowplug back in it, i hope i dont hear about it.... Heres the letter I have so far i will send it out monday, let me know if i should change anything in the letter....



Letter reads:

O.S. MAX .15 CV-X


To O.S. ENGINES MFG. CO
Brand new motor only 4 days old. Since first startup, when engine temp reaches approximately 220-240 Degrees (EXERGEN TEMP GUN), motor loses compression (Little Resistance On Pull Starter) and fails to idle and to restart. When motor cools to room tempreture full compression is restored and starts on the first pull. Followed break-in instructions per your manual. I have used OS motors before and never had a problem. And was disappointed with this straight from the box. This motor was in my touring car, and hardly saw road time. Paid almost 150 dollars and wasn’t expecting disappointment. Local Hobby Shop confirmed that something was not right. Also tried a new OS Glow plug with new gasket, with same results.
I was assuming it could be overheating, but followed break in procedure settings, temp gun read 220-240 degrees, and water hardly boils off the head. (6-8 Seconds For Water To Evaporate)

Used With Motor;
OS glow plug that came with my motor.
Stock exhaust.
“Clean Flow” New In-Line Fuel Filter
New Bottle Trinity Break-in Blend 20% Nitro
Hobbico After-Run Oil
And the 2-element air cleaner that came with the motor.

I had contacted OS Tech Support, and was told to check back plate and head bolts for tightness. I was also told that it could be a case flaw, or leaking bearing etc. I chose your motor over HPI due to good history. Due to the warranty I did not want to tear this motor down to take a look, I will leave that too you.




Appreciate Your Time
Anthony Rubano