tsawyer148

My Feedback: (8)

I have a Thunder Tiger Pro .46 that is starting to give me a little trouble. It has begun to leak a little more from the front bearing and is starting to hesitate a little in the air. In counting up the logged flights with this engine it is quickly approaching 135+ flights over the course of a year and a half in two different airplanes, which includes all my initial training and one serious crash, (stupid newbie mistake at the time).

My question is if anyone has a good feel for the life expectancy for these engines and whether this engine may have seen enough or if it may be another problem.

The engine has always had after run oil put in after every flight, has always had an aircleaner on it and doesn't really show alot of signs of being run too lean. It also still feels to have good compression, (I have another TT Pro .46 on another plane and the compression is pretty close to the same).

Just curious if anyone can answer.

Thanks,

T.

DBCherry

My Feedback: (4)

Not sure about Thunder Tiger, but I'd imagine life expectancy to be similar to any engine if treated properly.

From my experience and everything I've heard, you should get years and hundreds of flights from these engines. It may be that the TT bearings will wear prematurely however. I don't think that there's enough history available to really say. (Unlike some of the OS engines that have beena around for 20 years.)

This probably hasn't helped much, but....
Dennis-

tsawyer148

My Feedback: (8)

It has actually as I am seeing that you can find out just about anything you want about OS and other brands of engines. TT is another story however. It has been a great engine and I will admit, I have put it through hell..

T.

Gene Chernosky

My Feedback: (182)

...if you are mechanically inclined. It is a complete tear-down of the engine to do it. BOCA Bearings has the front bearing for ~$8 shipped.

Take off the head and backplate (notice that the backplate has an indention inside it, that MUST be towards the head on re-assembly)...set the screws in some light oil. Mark the back of the rod with a scribe or something so when you go back together you get the piston back where it should be. The sleeve might have to be 'encouraged' to come out by gently using a small screwdriver in one of the intake ports in the case and pry it out a bit to get it to move...DO NOT put the screwdriver inside the sleeve! Once the sleeve is out remove the rod from the crankpin...I have found that it will either come off at TDC or BDC...depends on the engine. The drive washer is a total PITA to get off unless you have a gear puller...if so proceed...if not, hmmm...you're up the creek Once the drive washer is off put the prop nut on the end of the threads to protect them and lightly tap the end of the crankshaft to get it to move out of the bearings....take off the prop nut and drive washer collet and totally remove the crankshaft. The front bearing can then be knocked out with an 1/4" extention with the appropriate sized socket on it to contact the bearing's inner race.

Now to go back together...use after-run oil on ALL parts while assembling!

Putting in a new front bearing can be a bit tricky, just take it slow to get it started in straight. I use a small ballpeen hammer and lightly tap it in all the way around the outer race until it is flush with the case front. Then take a socket that will contact the outer race of the bearing and tap it fully into place. Re-install the crankshaft...tap it in place. Re-install the rod/piston making sure the mark you put on it is facing the back of the engine. Bring the piston to TDC and VERY CAREFULLY slide the sleeve over the piston...DON'T force it, go slow to get it to slide in smoothly. Align the sleeve with the locator pin. Place the head back on and put in the screws. SLOWLY torque them down a little at a time by tightening them in stages...snug them down a little, then a little more, then the final tightening...all done by cross-tightening the screws to ensure even head tension. Put on the backplate and cross-tighten the screws on it...a little at a time, until they are snug. Remember, you're dealing with aluminum here, don't get gorilla handed!

Done

rogwabbit

Question about that engine break down/ re-build...

I found my engine to have a loose sleve.. Is this normal? When I pulled the head off, all I had to do was turn the motor and the piston pushed the sleeve up.. It's abc so I know it's tapered, but I didn't have to turn hard.. just with my hand, not even a prop attached.. Is that too loose?
If so how can I fix that?

tsawyer148

My Feedback: (8)

Thank you Gene,
I was kinda thinking it would be a pain, but I hate to just discard the motor. Like I said, I have put it through alot of abuse and considering the number of hard landings, prop strikes, (I used to buy props by the dozen), one really bad crash and the slow learning curve, I figure the engine has given me more than enough.

Could the bearing be the cause of it sagging off in the air as well? It is a real pain to tune and I have been having to add a little castor to my fuel, as well as running it a bit on the rich side. Doing so has helped immensly, but I guess I just want to be sure it is not something else I am doing wrong so I don't make the same mistake with my other engines.

T.

Strykaas

I've always thought gently heating the engine helped in taking away the bearings...
Don't u do it ?

FLYBOY

My Feedback: (11)

I have engines that are more than 20 years old and run great and don't have any problems. I have never had to change a bearing. All of my friends who start them and run the fuel out and use after run oil have to change bearings just like it sounds like you have to do. Thats why I tell people when they are done flying on any day, don't run the fuel out. There is pleanty of oil in it and you don't need after run oil.

Changing the bearing is pretty easy. I have helped others do it. Use the advice above and that engine will give you a lot more great service once you get the new one in.

Flypaper 2

I'm with flyboy. After my last flight I shut the motor off hot, with the motor hot, alcohol and nitro is vaporized so all you have left is oil. Never replaced a bearing yet and don't use afterun oil.

Strykaas

Quote
"Thats why I tell people when they are done flying on any day, don't run the fuel out. There is pleanty of oil in it and you don't need after run oil"

Great advice ! That's typically what I haven't been doing :bananahea ... I simply wanted to avoid having to remove the remaining fuel from the tank. Lazy man ... Thanks for the tip !

FLYBOY

My Feedback: (11)

Strykaas, If you don't want to remove the fuel, pull the line off the carb, and the line off the muffler, and put a piece of brass tube in the one from the carb, and plug the tank line into the other end. Then you don't have fuel filling the muff and dumping out every time you pick it up.

bsindel

if you leave fuel in the tank for very long the alchahol and nitro will evaporate and leave your tank full of .... ah .... yucky stuff.

Bill

Strykaas

Yep, that's precisely why i 'used to' empty my tank during my last flight ! No other choice than doing it manually now.

tsawyer148

My Feedback: (8)

Thanks for all the help. I have a new engine I am about to start using in a different plane, maybe I will forego the running of the fuel out and after run oil with this one. See what happens I guess...

T.

FLYBOY

My Feedback: (11)

I think it will last longer. I use marvel mystery oil if I am going to store them for long periods of time. Keeps them from gumming up.

Gene Chernosky

My Feedback: (182)

If you buy the 2RS sealed bearing from BOCA you are getting ripped-off...it is a pittiful excuse for a true sealed bearing...the Ultra Seal bearing might be better. Their standard bearing is fine as well as their high heat and ceramic (big bucks for the ceramic). If you want a 'for real' front sealed bearing for your TT PRO .46 go to your local auto parts store and ask them to get you a sealed bearing that is 3/8" ID x 7/8" OD x 9/32" width...the bearing is listed as an R6. It WILL be more expensive than BOCA's...but it will end the 'runny nose' and bad run characteristics on your engine.

I use 10% nitro/20% lube (1/2 castor/1/2 synth) fuel and OS #8 plugs in ALL of my two-stroke engines. Typically I will point the plane straight up at full throttle and adjust it to full lean. I have found this to be a good starting point to get proper in flight running...some tweaking might be necessary.

Rear bearings DO require heat to get OUT...most of the time. Sometimes they stay on the crank...not very often though. I NEVER use heat to put either of them back in. I put the front bearing in first then put the rear bearing on the crank and slowly tap it in place. YES, you do have to be very careful and not everyone can do it...so be forwarned.

Some engines do have a looser sleeve than others. I have had the same thing happen on some myself. I have had others that were a PITA to get the sleeve out of the case. Unless the sleeve is just about rattling in the case it is just fine.

I've only changed bearings in used engines that I have bought. Usually they are rusted and pitted so they don't turn smoothly. This typically happens because methanol is hygroscopic (attracts water...which then forms rust) and if your fuel has ANY synthetic lube in it that also causes rust. NO, I don't run the fuel out of my engines, but I empty the tank and use after-run oil EVERY time I'm through running an engine for the day. I have NEVER had to change a bearing on any engine under my care...no matter how hard I have ran it.

Spaceclam

the front bearing isn't sealed i don't think, and if it isn't, the leaking is normal. two strokes always have a lot of oil inside, so the dripping is normal. just put a paper towel underneath it and you will be fine. you may want to change the glow plug though. also, taking the glow plug out, bringing the piston to the bottom of it's stroke, and pouring rubbing alcohol in there. then, flip it over a bit and see if anytrhing happens after you let it sit until it has all evaporated. (note, it will take some oil along with it, becaue rubbing alcohol thins oil.) i don't think they are ringed either. but i think what you are beginning to experiance now is considered normal

Azcat59

Good advice from Gene, but while you are at it I would think about putting in a new rear bearing as well. In my experience, running engines hard in patter "back when" it was usually the rear bearing that went first.

And I firmly believe in running the engine dry after the last flight of the day, and after-oiling. Even in areas with low humidity as we have here in Phoenix most of the time.

Clair Sieverling
AMA 15654

spyder0069

You can leave fuel in your tank. Just screw in the needle valve which cuts off air from the engine line and then put hemostats on the muffler line or pull the muffler line and push in a plastic fuel stop (or fine thread screw of same size). Cuts off all air to tank and fuel stays as fresh as if it were in the fuel bottle. I usually take a paint marker and once the engine is tuned I make a small stripe on the needle valve so I always know where to start once its time to fly again.

Spaceclam

the nitro will soften the silicone tubing if it is left in there for long periods of time.

Strykaas

What does it cost to empty your tank ? A few seconds, so why take any risk ?

Azcat59

Fuel will eventually corrode and "eat up" the brass that is in the tank. It eventually ate all but the nylon shell of the filter that comes with the DuBro fuel can lid assembly. Better to drain it and leave the needle valve alone.

Clair

ssr70

I would not send your engine back to ace. You and your freinds will do a better repair.Take a look at my bad service thread.

ballgunner

My Feedback: (1)

The average time per flight is usually from 10 to 15 minutes. Assuming the 15 minute time per flight you only have about 35 hrs on your engine. According to Duke Fox if a model engine lasts 200 hours actual running time it is almost surely worn out. I know there will be lots of pilots who will say they've been using their engine anywhere between 10 and 25 years. Probably fly it two or three flights a week and not every week at that. Assuming they are lucky enough to fly 40 weeks a year at 45 minutes a week that still adds up to about 18 hours a year. That may account for the extended period of ownership but it still doesn't add up to a lot of hours of running time. The above should generate a bunch of controversy and doubts as to both my math and sanity. Oh well !!

Spaceclam

i know a guy with an old os .40 fp that has flown it every weekend (both saturdays and sundays) for 15 years. i asked him. he used after run oil, (just in case some of you in that after run oil thread are involved here) and he has never replaced the bearings. he is using the same prop as he did back then (10x6) cranking out a good 13,000