Enya 35 4C open rocker lubrication

[Fin 35]

I'm refurbishing a fascinating old Enya 35 4C open rocker engine for a friend. It doesn't look like it's had much running but it's gummed up with old castor oil and the bearings are rusty, so I'm replacing them. My question is about lubrication of the rear timing gears. There doesn't appear to be a vapour path to them from the crankcase, other than through the sliding fit of the timing shaft at the rear of the crankcase. So I assume I should partially fill the rear "gearbox" casing with oil via the tappet holes. This would serve to lubricate the gears, cams and timing shaft rear ball race. Any thoughts?

 

I've also noticed that the crankcase breather was blocked (!) and that the hole is only 0.9mm, which seems small compared to modern engines. The rear crankshaft bearing is unshielded and the front one is shielded on its front face only. Again, the only path I can see for oil vapour to reach the front bearing is via the sliding fit of the crankshaft through the front bearing housing. It seems odd that there isn't hole, or am I missing something?

 

Presumably the rockers need a squirt of oil before each flight?

[Jon H]

I think the oil finds its way into the cam chest through the open races of the pinion drive bearing. Its been a while since i opened up one of my enya's but if memory serves that is how it works. I would give it a good glug of oil on reassembly but it should sort itself out after that. 

 

The arrangement of the seals on the bearings also seems perfectly sensible and i would just leave it all as it is once the castor is removed. Ultimately the engine has been running well for more than 40 years so the core design is clearly just fine. 

[Engine Doctor]

The later bigger Enyas have, I believe  a small hole drilled through the timing drive mounting plate to allow oil ingress / egress. You could modify it ? It's near the bottom so could be for the oil to circulate rather than pool .

Most modern four strokes have similar arrangements for crank bearings and it seems to work OK.  The open valve Enyas were early days for fourstrokes any possibly not many users around to advise if there were any failure . Specter engine tests might shed some light ? I left mine as it was  designed as had no intention of using it other than sitting in my collection. 

Any good quality oil to lube the bearings and timing gear on reassembly will do. I use either mineral based two-stroke oil or air tool oil for assembly. Never had any problems other than a smokey first start.

Rear tappets should be oiled lightly prior to every run and wiped over after each session. 

Edited October 27, 2022 by Engine Doctor

[Jon H]

The small breather hole could be deliberate to increase crankcase pressure and force oil/air into the cam chest. As the cam followers do their thing there will naturally be some weeping round them

[J D 8]

             I have an Enya 40 4c which is in 110" span 10lb motor glider [ old Robbe kit flown now and then] While the Enya may have just enough power pull the skin of a rice pudding a long enough take off run gets it up if strips grass is short.  Mine is standard and although run on the castor stuff in the past it goes well on synthetic oil fuel today.

   One of my Enya 90's had the small hole in breather and after trying just about everything possible to discover why it would slow/stop after 5/6 minuets in the air. It was the build up of oil in the crankcase found to be causing the problem.  When back on the ground oil would drain [upright engine] in a couple of mins, engine would go again for a repeat performance.

      A swap to a larger nipple fixed it. The 90 was purchased S/H as little used and looking brand new. My 40 has the small hole nipple so I guess the 90 had the wrong one from new. 

  A nice dollop of car engine oil over the rockers is what mine gets before flying.

 

 

[Jon H]

Were you running 20% oil JD? Its possible more modern 15% would have helped with your hydraulic crankcase issue but obviously opening the breather had the same effect. I run my 53 enya on the current 5/15 fuel and it works really well. I have some other enya's not currently in service but i hope to get them into something eventually as i like them a lot. 

 

 

[J D 8]

 No, I been running all my glow motors 2 and 4 stroke [ except Cox ] on 5/15 fuel. The 90 problem was a few years ago before I swapped from 20% oil after reading your post's on the subject. I have two 90's in regular use as well as the 40, now and then. I just like them.      Cheers, John.

[Fin 35]

Many thanks for the replies and suggestions. I'll leave the engine as-is for now and see how it goes. If there are issues, I'll try a larger breather nipple first. Bearings are on order and I've even turned some fitting plugs, so the process will be nice and easy. My friend was thinking about putting it in a scale model but I think I've persuaded him to build a Super 60 with the aileron update - at least until he gets his 'A'. Instructors will be queuing up to buddy that one. Can't wait to test it on the bench!

[Jon H]

JD8. I have the 120 4c which is a bored 90. Flew it for years in a H9 pulse 60 on SMC 5/15+2 castor fuel and it performed very well. The model eventually fell apart and the 120 is currently sleeping under the bed. I also have the 53 in my Tomahawk, a 155 in a pulse 125 and an 80 (rare beast) in a box also waiting for an assignment. 

 

My 155 was a dog. Ebay job, 'runs perfect' etc. I have replaced most of the engine and its got a laser carb on it. Runs very well on the 5/15 fuel but i need to have a word with it as it destroys every exhaust i fit! 

 

Fin, a super 60 with that engine would be sedate but lovely. One day i will build one, i just need to buy one of those old hangars they used for airships as my list of models to build is quite long and i need somewhere to put them 

[J D 8]

     Jon. The 90 in the pic above was also an exhaust buster, hence the remote muffler. My other 90 in my Major Mannock is as standard and has given no exhaust problems.

[Jon H]

2 minutes ago, J D 8 said:

     Jon. The 90 in the pic above was also an exhaust buster, hence the remote muffler. My other 90 in my Major Mannock is as standard and has given no exhaust problems.

 

I made an exhaust out of a modified laser silencer grafted onto an old ASP 91 muffler. It worked fine but was loud so i made a new baffle and fitted it. Flew for a bit, nice and quiet...then it went too quiet and i lost all power. The reason? my aluminium baffle was melted by the exhaust gasses and it plugged up most of the holes in the original laser baffle leaving me with no power. I was also left with molten splatters all over the wing leading edge. Madness, the enya 155 is a beast. 

[Fin 35]

Just finished rebuilding the engine and ran it on the test stand. Started on the 2nd backward flick and ran beautifully. The forward facing glow plug is a bit exciting with a glow stick - fingers very near the prop! Now I have to give it back to its owner 🥲

 

 

 

[Jon H]

I saw .MOV and got excited for a video. Alas, computer says no 😞

 

 

[Paul De Tourtoulon]

On 27/10/2022 at 22:21, J D 8 said:

     Jon. The 90 in the pic above was also an exhaust buster, hence the remote muffler. My other 90 in my Major Mannock is as standard and has given no exhaust problems.

Mine too, a Rossi metal exhaust ring with washer,,,

 

http://sceptreflight.com/Model Engine Tests/ROSSI 61 RE.html