SmokinJoe

I trashed my TT46 engine yesterday when the glo plug element dropped out and went through the engine. There is no trace of the element left in the OS No8 plug that I was using.

The engine had been running normally for about a minute in the air when the engine died. When I pulled the engine apart last night, there was a fine grit in the combustion chamber and in the crankcase. The bearing cage was also coming apart with loose clips in the crankcase.

Has anyone else had a similar experience?

HighPlains

My Feedback: (1)

Most likely is the ball bearing failed and passed metal through the engine. It happens.

SCPYLONRACER

Hi Joe,
The rear bearing cage failure is common on the TT 40/46. When I get a new engine, I replace the rear bearing with a Boca Polymite plastic cage bearing.
http://www.bocabearings.com/
The standard steel cage rear bearing that comes in the TT 40/46 doesn’t hold up in a racing application.

The blown glow plug is a consequential damage from the cage failure.

Bill

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agree with all the words/replies............trevor h[>:]

SmokinJoe

Bill & Trev,

Were your engines write offs when the rear cage let go? I can't see any scoring in the piston and liner at this stage - but I haven't disassembled the engine yet.

HighPlains

My Feedback: (1)

Yeah, usually if a glow plug element breaks out, it bounces around the combustion area for a while before it gets kicked out the exhaust (if you're lucky). When not lucky, you will usually see some verticle scoring on the piston in one or more locations.

Bearing failure is not all that uncommon, an early sign is having the glow plug knocked out, as very small particles of metal will kill them.

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I'm just doing bearings as we speak on a friends TT46- he was lucky nothing has broken, except the front race. One of my own TT engines had the element go down the side of the piston- we call the end result 'railway lines'................I think you will understand what that means!
My own TT46 engine had been run 'quite hard' on a 9x6 APC prop so the maintenance factor had to be naturally quite high............I've learnt change the rod and bearings at 80 runs and hopefully you'll extend the life of the engine substantially. Hope this helps, trevor h

SmokinJoe

I had incredible difficulty removing the liner from the crankcase. I could get it about 1/2" quite easily, but no more. I tried heating the crankcase in an over for 30 minutes to no avail. I tried freezing it and then heating the outside crankcase - no go. In the end, I tried the popsicle stick on top of the piston trick - and finished up damaging the piston in the process. If it was not knackered before I started, it certainly was by the time I'd finished.

Has anyone ever encountred a similar experience trying to remove liners from TT40/46 engines before? How did you eventually get it out?

Has anyone ever tried using a gear puller with a block on top of the piston?

crasharama

HI Smoking Joe,

I have a TT61 pro that I have to change the bearings in twice a year. It normally runs about 15-20 hours before you can feel sideways play in the front bearing. The liner in this 1 usually comes out faily easily.

I only changed mine last week, & have found some differencs in tolerances between new & old bearings, even from the same manufacturer. This set, I had to leave the case in the oven for at least an hour, & freeze the crank to get it to drop in. Last set i could just drop the bearing in & the crank fell in place driving the bearing onto the face.

Another guy that flys in our club has just changed the bearings in his 46, & had alsorts trying to get the liner out of his. Wound up holding it in a vise & pulling it out that way.

Tony.

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never had a problem with liner removal- suspect though that something is now deformed, or the lost gloplug element is jamming the liner in the crankcase....it could be sticking on one of the ports. Sounds as though your engine is knackered( buggered). kiond regards trevorh

SmokinJoe

I measured the case and liner with a Vernier. The liner appears to be maybe half a thou out of round. The bottom OD of the liner and the case ID where it goes in are the same. I'd have to heat that case and freeze the liner to get it back in.

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hey Joe, suggest you buy a new one on the basis that:
a. the bearings are shot
B. the shaft could and more than likely is worn
C. the liner is out of round
sorry to be of the money spending attitude-as my wife say its time to replace with a new one- whatever she is talking about I wwish not to know
regards trevorh[:-]