TT 46 Bearings driving me nuts!

681 Views 9 Replies 3 Participants Last post by Spaz, Oct 13, 2004

John Wells

Discussion Starter · Oct 13, 2004

I've had 5 or 6 of the Thundertiger .46 rear bearings rust in the last few years. I always use good fuel, usually 5 or 10% nitro, and circulate plenty of afterrun oil through them when I'm done with each flying session. I returned the first couple engines to the manufacturer and they told me I was either using crappy fuel or I wasn't using afterrun oil???? I do it without fail. I've used everything from marvel mystery oil to prather afterrun oil.

The rear bearing rusts and spreads the red discoloration to the top end. Believe me, I don't let the engines sit for long and use them at least once a week. When it first happened a few years ago, I replaced the bearings with Boca high speed bearings and it still did it. The front bearings are always sparkling clean and not a problem. I thought maybe hanging the planes from the tail was causing the exhaust oil to run back into the engine, so I switched and started hanging them from the nose. That didn't help either. WHAT THE HELL IS GOING ON?? Am I doing something wrong that I don't know about?? I switched fuel 4 times during this period and I don't think fuel is the problem.

Has anyone else had this happen and does hovering somehow put an unusual load on the rear bearing? If it's typical with TT engines, what other brand 2 stroke won't do this? :?:

Thanks for your help,

JW

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Spaz

· #2 · Oct 13, 2004

i havent had any problem with mine and i never heared of this as a problem, marvel mystery oil is red, isn't it? do they feel rough when you turn it over? if they dont feel rough, i would just run them

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John Wells

Discussion Starter · #3 · Oct 13, 2004

They start out with just a rusty looking rear bearing, then the rusty film builds up on the liner and piston. Then the rear bearing starts getting rough and making noise. I'm pretty sure it's caused by somthing happening to the rear bearing. Maybe the rear bearing is heating up? The front bearing always looks shiny and feels smooth.

JW

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Spaz

· #4 · Oct 13, 2004

what %oil fuel are you using? what brand

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· #5 · Oct 13, 2004

........

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John Wells

Discussion Starter · #6 · Oct 13, 2004

Ritches brew 18%, Sig 16 or 18%, Wildcat 18%, and most recently, Coopers. A friend uses the same fuels and no problems with his MVVS engines, but he doesn't fly as much as I do and he doesn't 3D much. I don't have the problem with my Moki 210 in an OMP GS540, and I fly it the same way as the .40 size planes. No problems with my Webra .32 or TT 36 either, using the same fuel. Just these TT 46's.

JW

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John Wells

Discussion Starter · #7 · Oct 13, 2004

Constrictor, I used to not use afterrun oil and never had a problem either. I started using the oil after I had a couple of the bearings rust out. Using the afterrun oil doesn't help the problem. Same thing with or without it.

JW

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PaulSwany

· #8 · Oct 13, 2004

Does the fuel you're using have some % of castor in the oil mix? Have you talked to Brian at Cooper fuels to see if he might have an idea?? He's pretty sharp with engines....

Are you flying in swampy places and sometimes pretend your plane is a submarine??

Joking.... but I've never experienced this kind of bearing failure... My Irvine's uses to go thru a bearing set every other season when I punished and abused them, hovering for days without a break....

I wonder if something else is wrong with the engine? Some way for moisture to get in... Maybe a leak in the back plate... or carburator....

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John Wells

Discussion Starter · #9 · Oct 13, 2004

PaulSwany said:
Does the fuel you're using have some % of castor in the oil mix? Have you talked to Brian at Cooper fuels to see if he might have an idea?? He's pretty sharp with engines....

Are you flying in swampy places and sometimes pretend your plane is a submarine?? Joking.... but I've never experienced this kind of bearing failure... My Irvine's uses to go thru a bearing set every other season when I punished and abused them, hovering for days without a break....

I wonder if something else is wrong with the engine? Some way for moisture to get in... Maybe a leak in the back plate... or carburator....

I have used castor mix, then I switched to synthetic. I haven't submarined it :lol: I even started plugging the carbs and exhaust outlets with those red rubber caps like the things that come on the ends of the glow starters. I'm sure they're pretty much air tight when they arent' being used. The engines run great, but the bearings start making noise after about 2 gallons or so. At one point, I thought maybe the crank was spinning inside the rear bearing, so I used the red locktite to stick the bearing to the crank. That engine did the same thing. TT replaced the most recent engine and pointed out all of the rust. K.C. weather is pretty humid, but why don't my other engines do the same thing? Weird :roll:

Oh, one other thing, I store them in my basement and always run a dehumidifier down there.

JW

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Spaz

· #10 · Oct 13, 2004

Ask cooper what he thinks i be he has an opinion on this

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