I haven't had this engine very long. Less than 1 gallon of fuel.

I broke it in as you should any ABC engine. I used a fuel with 10% nitro and 22% total oil content with an 80/20 blend of synthetic/castor oil. I burned that fuel for about 5/8 of a gallon.

Then I switched to Omega (pink) 25% nitro. 3 tanks of that as of today.

Engine deadsticked today on my second flight. I figured it was just out of gas; as I'd flown it around for almost 20 minutes. I deadsticked it in and set it on the table for about 30 minutes. When I went back to fly again, I decided to make sure that it was indeed out of fuel, but it wasn't. I figured- maybe the plug- but it was in good shape. So, I flipped the prop without the plug in the head and it wouldn't turn over smoothly. It turned over kinda stiff and it was obvious that something internally wasn't up to snuff. I only turned it over that 1 time and then decided to stop and go home for the day.

I took it completely apart and have discovered that the front bearing is hanging up and dragging pretty bad in one spot. I also discovered a gall mark or burr on the front of the crank- right on the front shoulder where the crank rides on the bearing.

Rod bushing and crank pin appear to be in fine shape. Nice and shiny with no indication of overheating there. Cylinder looks shiny and smooth throughout. Piston shows minimal tanning on the top and minor brown spot on the exhaust side.

I suspect that the front of the engine had a piece of metal or slag in it from the factory. I took the backplate off the engine and removed the cylinder/piston when I pulled it out of the box. I usually do a minor inspection of the back-half of the engine before I bolt it up and light it for the first time.

I guess- in the future- I'll have to completely dissassemble every engine right out of the box. When looking at the damage to this front bearing and the crank shoulder up front- it's pretty obvious that some foreign material got hung up in there and put the hurtin' on the front half.

Hopefully, this is just a fluke. It's possible for any engine to have a piece of foreign material somewhere inside when it gets shipped form the factory. I'll send it to TH and see what they can do with it.

I can honestly say that this is the first time in 5+ yrs of modeling that I've come across an engine that had problems. I've worn a few out after many hours and gallons of time; but never had one toss a bearing after 1 gallon of fuel. Guess it was just my turn.

There's not any room up around the front bearing for a metal filing or slag to be in there. The bearing itself must have been contaminated?

Enjoy,

Jim

Thats a good point. Crankshaft fits in the case very snuggly. Can't see where a piece of foreign matter could have gotten in there. Must have been a bad bearing.

I was thinking about just getting a new bearing from Boca and fixing it myself. I'm not the kind of guy to piss and whine about too many things. Might be easier to just pop the $7 or 8 bucks for a new one and fix it here at the house.

Bummer.... I would expect Tower to repair/replace if it is still under warranty, and since it is clearly a manufacturing defect, good customer service should move them to make it right if it is out of warranty...

Cheers!

Jim

Tower will probably send you a new bearing if you asked them, but
you could probably get a better bearing for 10-12 bucks at a bearing
house.

Dave.

I'm not saying that Tower won't take care of me. Not at all. I bet they'd send me a new engine if I pressed the issue about the galling on the front shoulder of the crank.

I just would rather take a bit of 1200-2400 grit emory cloth to the crank and put a new bearing in myself.

As Flyboy suggests, I could probably get a better bearing locally for the same cost as the shipping and headache involved with the warrenty.

I'll let you guys know what it costs to get the bearing locally. Too bad, I liked this engine up to this point. I've got it on a 46 size Chief Giles 3D. It hovers at 1/2 throttle with a Pro Zinger 13-5 prop.[sm=spinnyeyes.gif]

I'll have it up and running again before next weekend.

I called Tower today.

They are sending me a new crank and a new front bearing-- no questions asked. They were very friendly and willing to help out without hassling me in any way.

Parts expected to arrive by next week.

Thanks Tower Hobbies.

I busted a brand new Tower .75 crankcase in a bad crash, on a maiden flight.
I called Tower and ordered a new block, and the misc. bits to change it out.
Tower sent me a new muffler for free....just to help me out....

.... [sm=thumbup.gif]

This is the third different thread that I have read concerning front bearing failure on the Tower .75 engine. It makes me wonder if the company that Tower has manufacturing engines for them are using cheap bearings that aren't up to ABEC standards. For what Tower is charging for these engines they have to cut costs somehow! I am still going to take my chances and order an Tower hobbies .75 for a scratchbuilt F15 Eagle pusher prop jet that I am building.

As a side note, I once paid over $300.00 for an MVVS .77 rear exhaust engine equipped with a tuned pipe for a Great planes F4 Phantom and I was totally disappointed in the performance of the engine and Morris hobbies who is the distributor of MVVS and is who I bought the engine from. I had nothing but problems with this engine and never got it to run properly. After burning out numerous glow plugs and having problems getting peak performance out of this supposed powerhouse .77 I removed the rear plate and was horrified to find huge pieces of molding slag and flash (pieces of metal that are hanging off of the rough edges of moldings and castings) rattling around in the crankcase and occasionally making there way through the intake port and into the combustion chamber where they would cause the glow plug to fry and fail! I called the owner of morris hobbies and was rudely told that I would have to "make it quick" because he was at a flying meet and was answering his cell phone! He casually explained to me that there must have been "small shavings from the drilling and tapping process to custom fit the tuned pipe header". WHAT A BUNCH OF CRAP! I wasn't born yesterday and I know molding flash and slag when I see it! He refused to fix the engine and wouldn't even authorize paying the shipping to have the engine repaired and only got ruder as our conversation went on! The engine was trash and I was so pissed off at the whole ordeal that I ended up selling the beautiful F4 phantom that I had taken almost a year top build in the colors of the Blue Angels, of course I did the right thing and sold it for a good price and informed the buyer of what had happened with the engine and my bad experience with Morris hobbies!

Other people I have flown with have had great success with their MVVS engines and swear by them for performance, so it just goes to show that it all depends on whether or not you get the luck of the draw when a company pulls an engine off of the shelf and ships it to you!

I have had nothing but good experiences with Tower hobbies customer service and I will gladly take a chance on buying their .75 knowing that if anything goes wrong I have the best hobby shop in the world to stand behind their products!

I see this thread is over a year old. This Tower .75 ran in the F-20 for many
flights over a two year period....always wide open. I pulled the engine down
to change out the mains....just as a matter of periodic maintenance in an
engine that had been run to the max....and also to pull a shim out of the
head gask for a little more steam.

I never pulled the bearings out....I checked them thoroughly....no play, no
pits....no nothing. I left them them in there....and trust me, I would have
changed them out at the slightest provocation....but they were perfect.

I happened to tach the engine before the last run. It was turning the 11-7 1/2
MAS at 14,000 even....the same as it did two years previous when it was new.

What a great engine for under a hundred bucks. [sm=thumbup.gif]

FBD.

There are two Tower 75's at my field and I've never seen or heard of any problem with them.

Enjoy,

Jim

The only problem I had with two of them, was the rear muffler oulet would
turn when the engine got hot in flight. I quickly cured that with a couple short
fat pop rivets....one in each seam.

FBD.

From what I hear, the tower engines are using the tooling for the old Super Tiger S series of engines. They obviously changed the Carb and Muffler design. But based on the way they run, I am sold on this "Old Technology" LOL

I read that somewhere too. I don't recall ever seeing a S.T. that looked like
a Tower .75, I've been using the Towers since they first came out, and couldn't
be more pleased. They make the same exact power as my old OS .60 FSR's
with the special pipe....which is very stout.

The cylinders and the machining on the ports in the Tower is as good as anything
on the market.... IMO.

FBD.

The Tower 75 was alive and well long before the same company started making the Super Tigers in China.

Enjoy,

Jim

I know they came out before ST was moved to China, but the S series of engines was 2 generations of engines ago. So the tooling for those could have been moved long before that. This also explains why Tower can sell them so cheap. These engines do strongly resemble the ST's from the early to mid 80's. My Tower 60 crank case is almost Identical to the ST S60 I have from 1982. All the porting and timing look about the same too. In the late 70's to early 80's ST was known as a hot engine, especially the Series X motors with the PDP porting in them.

1. No R&D costs.
2. Made in China where labor is 10 cents a week.

Maybe the Hobico rep can give us some insight on this, Tower does fall under the same corporate banner, even if they won't acknowledge it publicly. LOL (Area 51) LOL

You are getting a little far fetched now? Why don't you call Tower and tell them that the Tower is just a Super Tiger?

The sleeve and piston assemblies are interchangeable between the Super Tiger S-61 the S-61K and the current G-61 series and the Super Tiger 75's are all interchangeable with each other.

Enjoy,

Jim

I can't say....the olny two Tigers I had were purchased in about '74. a .46
and a .60. The .60 didn't look like a Tower....the head on it stuck way up
in the air, and if you look up "ugly" in the dictionary....

....you will see a picture of the muffler.

FBD.