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Question about glow plugs and the 3.3 Revo

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M

Mitco39

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I have a quick question...

I recently bought the 3.3 Revo and i have had a couple issues with it that have been resolved with changing the glow plug but i want to know why it was the glow plug that caused them.

The engine will start and idle fine... however any bit of throttle over 1/4 and the engine will fall flat on its face and die... Now i had a buddy with me who said to change out the glow plug, but i argued with him saying it was only needed to start the engine... So after 2 hours of tuning and trying to get it running I finally took his advice and changed it... And the thing ran as good as one could have expected.

So i was curious as to if the Glow plug serves another purpose other than just starting the engine?

Thanks

Mitch
 
it works the same as a spark plug on a full size engine. It causes the gas in the combustion chamber to combust. The way that it works is like a diesal engine though once the plug is hot every stroke that the engine fires on causes the plug to maintain heat therefore causing the next stroke to combust.

hope this helps
 
Thanks for the replies...

I'm am familiar with a diesel engine... but that doesn't really explain why it wont stay running once its started. I know the plug needs to heat up to help the fuel ignite initially, but why would a plug change help to keep it running?

I was playing with it more today (i ran outta glow plugs) and it would start and i even had it idleing fine with some adjustments... but it would not take any throttle... and i played with the high speed... I must have made 30 1/8th adjustments on it... both leaning it and riching it.. but it had no effect on the engine falling flat on its face.

Maybe there is something in the plug that stays hot throughout the stroke to help ignite the new fuel?

If i was able to just heat the glow plug while it was started (kinda hard to do with the ez start without cranking the starter while its running) it would have stayed running... and sounded great (A couple stabs with the ezstart on... didnt wanna burn out the clutch or the e-start)

So I'm not quite sure whats going on...
 
Sounds like you have a bad leak somewhere. Look at the exhaust coupling, a tiny tear in it will cause it to do that.
Check everything that is rubber on the engine and fuel system for knicks and such.
How old is the engine?
it could be any of a number of things. Tear the engine down and inspect it.
 
if your glow plug is not holding heat then it wont run try a different heat of plug and def chack for air leaks
 
Then engine has maybe 5 hours on it...

It still doesn't explain that as soon as i change out a seemingly good glow plug it runs like there is no 2morrow... if there was a leak of anykind changing the glow plug would not do that...

The only thing i can possibly think of is that the copper washer for the glow plug goes bad and when i change the glow plug i also change the washer elimating the leak...

I dunno...
 
You can have a plug that lights up but is not good enough to keep things running.If you are going through plugs quickly I would say richen the bottom end an hour or two and try again.I am no expert but I just went through this and I was reading the glow plugs and anjusting accordingly and now all is fine.There are some good pics and info on reading glow plugs but you need to dig for em cause I don't know where there at.I am getting better at tuning and troubleshooting but I still can't get this OS .21TM figured out.
 
The TM runs hot Captain, it's that simple really. I dug around a bit. A lot of people have reported that they run in the 250-280F range. Mine is running that hot, but the plugs are coming out wet and looking like new. 4 different plugs have been in it, they all look new still. Quite a few other O.S. engines i have seen like to run this warm as well. If you read through O.S. manual and web pages you'll notice they say nothing about temps. Tune it where it runs good without killing plugs is all they say. My 3.3 ran in this range as well and still had a ton of pinch at three gallons.
 

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