mach2

My Feedback: (5)

Hey guys, I think i need to replace my bearing. Lemme know if you think my issue is something different from the pic i attached. The amount of black oil pictured is after flying 4 flights.

I DO have my thrust washer in. And I've got lessthan .005" of play for and aft.

Are there any "how to" links or videos on how to fix this issue, and where can i find the parts? I couldnt find anything at tower.....

The engine is a Thunder Tiger GP-42

thanks guys,
Jeremy

Campgems

Jeremy, your photo didn't attach. where is the oil coming from?

Don

mach2

My Feedback: (5)

Okay, the pic is up now. its coming from where the shaft comes out of the crank case. Where the thrust washer is.

thanks,
Jeremy

Crash Campbell

Hi,

Is there play from side to side? Is there a "grumbling" type noise when the motor is running? With the plug removed does the motor turn over smoothly without any noise or catching? If the answer to any of these is yes then it is a good idea to replace the bearings. It is a fairly simple matter to replace the bearings. Remove the barrel and piston then heat the crankcase, wear heavy leather gloves, and tap the crankshaft, (with the nut in place to ensure the thread isn't damaged) on a piece of hardwood to remove the rear bearing. Reheat and use a wooden drift, (piece of hardwood dowel) to remove the front bearing.
Take the bearings to your local bearing service and they will match them. Remove the seals that face into the motor before re-installing.

Cheers,

bingo field

http://www.bocabearings.com/faq.aspx#help-rc3

"Place your engine housing in an oven at 325°-350° for 5 to 10 minutes. When you remove it from the oven your old bearings should fall right out, if not heat the engine a little longer. We also suggest you place your bearings inside a ziploc bag and keep them in the freezer overnight. Then slip the bearings into the engine while it is still slightly warm."
These instructional videos show how to remove and install RC Nitro Engine Bearings Part 1, http://www.youtube.com/watch?v=WhpwsjYoxM0

Part 2 video http://www.youtube.com/watch?v=Q3xIW...eature=related

Campgems

OKGuys. the Thunder Tigre GP-42 doesn't have a nose bearing, and I'm not sure about the main. It is a bushed crank, not a ball beraring one. Given that, get some good cleaner and clean your plane after every couple flights and don't worry about it. What you are seeing is blow by out the front bushing. Not much you can do about it. short of some serious machine work.

Here is a photo of the crank case http://www3.towerhobbies.com/cgi-bin...?&I=LXAJKM&P=Z

Here is the total parts breakdown http://www3.towerhobbies.com/cgi-bin...I=TTRG1041&P=Z

And here is the manual. Notice that there are no bearings to be replaced on the break down drawing.
http://manuals.hobbico.com/ttr/gp-series-manual.pdf

Don

PS now I'm sure about the main being bushed also.

rcjetflyer0718-RCU

My Feedback: (1)

If you purchased the engine within the past 3 years and have the receipt you can send it to hobby services at Postal Address:
Thunder Tiger
3002 N. Apollo Drive, Suite #1
Champaign, IL 61822

and they will repair or replace it for free unless the damage was caused by a crash or misuse.

mach2

My Feedback: (5)

Its a thunder tiger MKII trainer that was purchased about 5-6 years ago and has been in the box up until about 2 months ago.

there is no play side to side and it sounds good and runs well. Its only got a gallon and a half through it, and I've made sure my props are properly balanced.

Campgems - I forgot that it's a bushing motor. Thanks for the reminder. I suppose it is what it is, as you pointed out. If it gets super bad ill just get a new crankcase and a gasket set.

Do you think it would help reduce the blow-by if I used a thrust washer that is .001"-.002" thicker?

Thanks,
Jeremy

Campgems

The thrust washer has nothing to do with it. It is the clearance between the bushing and the crank. With no more time than you have on hte motor, it isn't worn. Just get some good cleaner and just fly it.

Most two stroke glow engines dump a bunch of oil anyways. Even the glow four stroke can make a mess of things, but for the most part, that doesn't mean that they need repair. If it ain't broke, don't fix it.

Don

mike109

G'day

The GP series of engines are like the FP and LA series from OS. They are bushed or plain bearing engines. They do not have ball bearing races and so the bearings cannot wear out. There are none. the "bearings" are replaced by a bronze bush.

These engines like fuel with plenty of castor oil in the mix. The more the better. They do not need a lot of nitro either and will run fine on FAI fuel (20% castor oil and 80% methanol). If you run the engine on fuel with a large proportion of synthetic, oil you can damage the bush and if the bush wears, the engine is effectively worn out and cannot be replaced.

So .....

I'd suggest you find some fuel with 5 or 10% nitro and as much castor oil as you can find. At least use a fuel with some castor in it. This will really help the bush to last.

If you are getting black oil from the engine, this is either wearing alumimium and or wearing bronze. Check the tightness of the muffler as this is often the cause of black oil.

Hope this helps a bit. The GP engines are great sport engines and with the standard, are very quiet and work well in trainers and small scale models.

Cheers

Mike in Oz

pimmnz

Yes, it looks like there is ally wearing. Two things suggest themselves, either the steel washer behind the prop driver is rubbing on the crankcase nose, (it shouldn't while the engine is running as the prop should pull the shaft forward) or the prop driver is rubbing on the cowling, the photo shows that the cowl is pretty close to the prop driver, the muck is coming from the front, and you can't tell if anything touches until the thing is flying, and it can be hard to see. There will be witness marks on the driver or the washer if there is any rubbing.
Evan, WB #12.

mach2

My Feedback: (5)

Its flying well, so im just gonna do like Campgems and fly it, and clean off the soot.