All,
I am having a problem with an Enya .19-IV which I would like some advice about.
I recently attempted to bench run it, and found that while I could get it to run out prime bursts, it would not sustain a run. After a couple of attempted runs, I noticed that it had developed a tightness at the bottom of the stroke which wasn't apparent before trying to run it. (It had been stored with after-run oil in it, and appeared to be turning over freely).
On disassembly, I found :-
- spraybar & needlevalve in good condition. Initial thoughts were toward a spraybar blockage, but none was apparent.
- piston / liner fit seems very good. When removed, the piston will push through the liner with no tightness. With the head on, compression is superb - typical Enya, takes ages to leak away. There are no obvious scratches in the liner, no obvious distortion, and no varnish build up. Just a bit of carbon on the piston.
- conrod & gudgeon pin seem to be in good condition.
- after removing the front housing screws, there was no apparent damage to the bearings. The crankshaft spins very freely - if I give it a flick it will rotate maybe 10 times before stopping. There is very little slop or play - I can push the shaft back & forth only a fraction of a millimetre.
- gently tapping out the shaft to get the prop driver off, proved that the shaft & bearings are in good order. No scuffing or damage from siezing is apparent.
At this point, I was somewhat confused as to why the engine had seemed tight. Everything looked perfect. Then after a thorough clean & oiling I re-assembled.
On re-assembly, everyting went together smoothly until I tightened the four front housing screws. When fully tightened, the engine is 'grabby' at the bottom of stroke. If I loosen the screws off a fraction of a turn the engine is free & turns over readily. It is as if there is some sort of distortion of the crankcase, or perhaps the front housing gasket has over-compressed (or unevenly compressed?) resulting in the front of the crankshaft being slightly out of alignment, or the crankshaft being too far back and slightly fouling the conrod?
Is there any solution, or is this engine doomed to be a display piece? Possibly cut myself a much thicker gasket? I don't see how this formerly good running engine could just suddenly develop a distortion - certainly it wouldn't heat up enough to do so just running out a couple of primes of all-castor fuel.
Any ideas?
P.S. Its not the end of the world if its dead. It doesn't owe me anything, and I have another good Enya .19, an OS 20 and a PAW 19. I just wanted to use this old long-stroke Enya in one of the models I intend building over Christmas break.
cheers,
Colin
Re-learning control line in Brisbane, Australia.