Doug D.

Question for all those flyers that are running a Tower .75 ? I have one on the test stand for a little breakin time and needle adjustments and have noticed a problem that even Tower can't fix.
When pulling the throttle all the way back and closing off the carb barrel the engine keeps running. Very low idle but it still runs. Tower gives me a I don't know answer and says that even the .61 does the same thing.
I've resealed the carb O ring seal at the case, even the pinch bolt the holds the carb on, I've resealed the inlet nipple to the throttle body and the nut on the side. I've checked every where I can think of but can find no leaks any where on the engine. Externally that is. It shoudn't keep running when the barrel is closed. A friend has a sister engine a GMS .76 that doesn't do that. We swapped Carbs and the Tower .75 still runs when the barrel is closed. Very fustrating.
Now I do like the way the engine runs other wise, has good rpm's and good transition. But not shutting off when the carb is closed all the way is wrong. Love to hear everyones thought's.
Thanks !!!

Redwind

Definately sounds like a air leak somewhere in the engine. One thing you did not mention doing was sealing the back plate. I always use a small amount of high temp sealer on all new engine backplates as a standard proceedure. While the backplate is off check it carefully for cracks or holes. I had a new engine with an air leak that was the result of an invisable casting flaw. The only way I found it was to fill the plate with fuel and watch for leaks on the opposite side.

If all the the obvious spots for leaks have been covered the last place to look is the front bearing. I've never had Tower Hobbies engine but it seems that I've read here that your problem is a typical one that is a result of the bearing leaking. You might do a search and see if you can find out some more info. Good luck.

w8ye

My Feedback: (16)

This often happens with the Tower and GMS engines of all sizes. My Tower 46 does this from about the 20th flight on. It's not right but doesn't seem to hurt anything either. It has 100 flights on it now and it didn't get any better or worse. There's aguy at the field that has a 46 that does the same thing. He also has a couple 75's but they seem 'OK'.

Enjoy,

Jim

Pilotsmoe

my .75 leaks.

rockom

My Feedback: (2)

I think this is why you engine won't quit.....it's not supposed to.

In a previouse reply someone said the GMS is similar to the Tower engine. I have a .40 GMS and like it so much I ordered the .47 for my next plane. Anyway, my engine arrived in the mail today and inside was a customer note. Here is what is sais.

CUSTOMER NOTE:
THIS GMS ENGINE IS DESIGNED TO PROVIDE OUTSTANDING HIGH END POWER AND A VERY RELIABLE LOW SPEED IDLE. THIS ENGINE IS NOT DESIGNED TO "SHUT OFF" WHEN THE THROTTLE IS CLOSED. THOUGH SOME ENGINES WILL "SHUT OFF" WHEN THE THROTTLE IS CLOSED, FAILURE TO "SHUT OFF" IS NOT A DEFECT IN THE ENGINE. THIS ENGINE MAY BE SHUT DOWN BY PINCHING OFF THE FUEL LINE, REMOVING THE FUEL LINE, OR BY INSTALLING A SERVO ACTIVATED SHUTOFF IN THE FUEL LINE.

So, I hope this keeps people from bying a bunch of replacement parts and messing with an engine that is running just fine. I personally will continue to buy lots of GMS engines. (I just put my finger over the carb to cut the engine when needed)

-Rocko

rockom

My Feedback: (2)

One more comment.

An engine that needs a little help shutting down is a small price to pay for what you are getting....at least with the GMS. They are very low cost and in my opinoin as good as an OS FX series engine. Plus they are still readily available with a needle right on the carb where it belongs.

-Rocko

Azcat59

Guys seem to worry a lot about this.....several of my engines of various brands do this.....just taxi up to your feet, run the idle down very low, and use your hand to apply slight friction to the spinner.....very easy to stop them, even 120 size. Just doesn't bother me a whole lot.

Clair

Doug D.

Thanks for all your input guys. I did check the back plate seal, no leaks there. I'm having my friend look for his GMS manual, he didn't remember reading anything about customer notes ! Not sure what he read, just glanced at the important stuff.
If I find out anything I'll post it. Thanks Again !!!