As I was breaking my new engine for my car.. i Noticed that there is some kind of hissing sound coming out of the glow plug.. This happens especially when i adjust the mixture... and sometimes it would go away..Im pretty sure i tighten the glow plug... any suggestions? Is this normal?

do you have a copper washer between the glow plug and the hole? do you notice any nitro fuel bubbling out under the glowplug? if so then it not tight enough or you need a new washer. dunno otherwise

your engine sounds like its leaking air our of the glow plug hole. make sure you are using a good washer gasket and that you are tightening it down enough. simply turning it in until it stops is not enough to keep it from leaking.

so does that mean i lost a significant amount of compression? this was just the second tank of gas ever used on this engine..

The compression will be lower if the plug is loose, but thats not permanent. You'll gain it back if you tighten the plug. It usually takes about 1/8 turn after the plug bottoms out to get a good seal. You want it tight, but not too tight. Most heads/head buttons are aluminum, so you can strip the threads if you go gorilla on it, but give it a good snugging and try it again

I was also told on this forum that the washer has a side that faces the glow plug and button. if you look at the end of the thread towards the head of the glow plug notice that it is not that flat. now look at the washer. put the side that would mesh perfectly..

Good point. Also, make sure you CLEAN ANY DEBRIS in that area.

Small chunks of dirt can cause an airleak too. Worse, if they get in your engine, you'll be out $150!
NEVER let any dirt enter your engine. Typically, when I take out my glow plug, I hold the car/truck upside down/sideways if ots dirty. Then I give it a good shake to take out loose dirt. Do whatever you must to keep dirt from falling in through that hole. Just a word of caution

Ram

There are two different sides in a washer? A flat and a not so flat? Im lookin at my washer right now.. i dont see the difference..[&:] ...and i tighten the engine up too..

You are possitive that the glow plug is nice and snug???

yes..positively sure its snugged...its the OS engine .12.. the plug start is pretty tight when i pull it too... its a small hissing sound..checked for all screws..all tight

some more ???S

is there oil coming from the glow plug hole???

also does it do this when you turn the engine over by hand???

Im starting too think that its something else thats making the noise.

yes..oil is relatively coming out from the oil..not as much..before it used to squirt out bubbles.. i dont understand ur hand question...can i move? yes...but not easily

Try removing the plug again, and wipe everything off. wipe off the head, the plug and the washer, so that everything is really clean. Put the plug back in and tighten it. If it still leaks, try a new glow plug. If that doesnt help, you will probably have to take the engine back to where you purchased it or send it to OS for a warranty claim. A good hobby shop will back what they sell, and OS will help you too, but that can take a while if you have to mail in the engine

Ill agree with nitrofan, Try a new plug, if that doesnt work I would contact O.S. directly. im sure they will help.

If:

No known debris is between washer and head or between plug and washer...

There is known "good" washer...

Knowing the plug is well and good tight enough...

And there is still leakage, knowing that it's a brand new engine, it's very possible that the head or head button was not machined correctly or the plug itself is not.

Try different plug, if problem persists, I’m going with my theory of machining problem. It’s rare but not unheard of.