Irvine 53 Issues

[Scruffmeister]

Hi All,

I recently acquired a brand new Irvine 53 Mk2 (Japanese version, silver cowl). Ran it in on bench with about 1L of fuel per instructions, got the ABC lining nice and warm for short periods etc. All absolutely flawless. After run in would turn over nicely and freely with a finger and had a nice compression.

I put it in a model and tried to start it, it popped and looked to start but I noticed the prop was slipping a little so obviously stopped to tighten the lock nut. Issue was that the prop was locking against the spinner backplate but not the prop hub on the engine allowing the latter to rotate slightly. (I ran it in without a spinner on my bench).

So, the issue... I tightened the prop nut until the spinner backplate and prop hub actually locked. This required more torque than I would normally expect but done by only a small 6" spanner so I didn't think excessive. However, now when I go to turn over the engine it is stiff through the entire cycle to the point you can hardly detect it going over TDC. In no way does it feel like it would be safe to start.

I've check it without spinner, e.g. just prop on hub + nut and exactly same stiffness so something has changed mechanically in the engine. I've check there was no contact with the cowl inducing friction and I've checked the engine wasn't flooded (it wasn't and did turn over, just suddenly very stiffly).

So, I've broken it - but exactly what have I done!?

Edited By Scruffmeister on 16/09/2017 15:50:34

[Jonathan W]

It is possible that you have over-tightened it and forced the prop driver back on the crankshaft far enough that it is now in contact with the front bearing housing of the crankcase, hence the extra friction you now experience. Is the prop driver on a taper collet? if you are really unlucky, the forcing it back too hard on the taper might even have split the prop driver.

Solution? Undo it and try to examine the prop driver. See if it split or is sitting hard up onto the front of the crankcase.

[Denis Watkins]

It is easy to say that there should not be enough room inside the crankcase to compress the assembly, but something has moved.

I can only think that the front bearing has come out a smidgeon and allowed the rear crank to make contact inside the crankcase. Have a look see if the front bearing is level with the front housing.

Hopefully, one of the bearings has not collapsed.

I would use a suitable drift on the end of the crankshaft, where you screw the prop on

And give it a sharp smack to send the crank the other way.

If it did free off, I would be tempted to fit a thrust washer, available from Modelfixings, between the large rear crank and its bearing

Keep us informed

[Steve Hargreaves - Moderator]

Agree with Jonathon here Scruff...you might have forced the prop driver into contact with the crankcase....if you take the prop off entirely is it still stiff to turn?

[Scruffmeister]

OK, did some more investigation - with the prop off, I can push the prop shaft back/forward approx 1mm. When pushed right back I scan hear a scraping noise which sounds to be coming from the back of the engine. When pulled forward the noise is gone, but I can't tell how freely it rotates since my fingers can't turn the engine over with only the prop shaft to grip. When the propeller is put back on, no play is noticeable and the issue remains per my original post.

I tried a couple of sharp tap with a hammer as suggested but it had no effect, positive or negative!

So, how much work are we talking to dismantle and engine like this, get to the bottom of the issue and fix it? Although I've got experience of running glow engines I've never tried to fix one that was in a sorry state. This was meant to be a quick Winter hack for my local field as I don't tend fly glow models normally - with other build issues on the model itself I won't bore you with, it's turning into the project from hell!

Edited By Scruffmeister on 16/09/2017 16:53:35

[Mike White 3]

I had the exact same problem a couple of years ago with an SC46, turned out that during move from bench to aircraft I had dropped the very thin trust washer that sits between prop driver and bearing, without this clearance is nil. Just a thought.

[Steve Hargreaves - Moderator]

With the prop shaft pushed back it is possible that the crank pin (the bit the conrod big end is connected to) can rub on the back plate & this is probably the cause of the scraping noise. In use the prop tends to pull the crankshaft forwards so no contact between crank pin & back plate in normal operation.

Ooooo...no tapping with hammers please....always apply equal amounts of intelligence & brute force...in other words...if you're going to apply a lot of force to something....think really really hard about it first..

If you take the plug out you should be able to turn it over no problem.....you will feel a bit of tightness as the piston reaches TDC due to the ABC set up. If it feels tight all the time something is definitely wrong.

They are easy enough to take apart....about 10 screws that's all but there are a few traps for the unwary...try Uchoob for some "How To" videos or if you don't fancy it maybe a clubmate could show you how to dismantle it or failing that I'd be very happy to take a look at it for you....

[Denis Watkins]

Right, you started with, and still have a brand new motor.

Look on YouTube for a bearing change.

This is how far the motor needs opening up.

The bearings may be damaged, but you will see.

Work with what we have, and hide the 6" spanner

[Denis Watkins]

You beat me to it Steve

[Scruffmeister]

OK, thanks all - let me do some research! Won't hurt to learn...

[Stevo]

Stripping a 2S really is no issue at all... There will be resources on You tube etc. Not sure where you are (i'm in Kent) but happy to take a look if you are local

[Keith Berriman]

Reading in depth I am unable to confirm the prop driver to the shaft. Mark 1s had the tapering brass collet to the prop driver not sure if the later models went with the thin still shim behind the prop driver which is critical part of the engine set up. Can you advise us so we can suggest the way to go ?

[Martin Harris - Moderator]

I can't see you doing any damage with a 6" spanner. Assuming the design hasn't changed dramatically, the split taper collet tightens between it and the front of the crankshaft across the inner part of the bearing so you can't damage that with any conventional spanner - and it doesn't put any load on the rear bearing!

Two things could cause binding - an undersized taper or oversize driver (caused by prolonged slipping?) or far more likely, as has been mentioned, a missing shim washer between the face of the bearing and the inside of the prop driver. This will allow the driver to foul the front of the crankcase and give exactly the symptoms you describe.

[Scruffmeister]

As foolish as it makes me feel, it looks like the thrust washer is missing!

I've ordered a new one from Just Engines... just hoping that no damage has been done to the engine now by tapping the crankshaft with a hammer and generally turning it over a few dozen times while this symptom persisted.

Just need to wait for the postman now...

[Rick Tee]

This engine is prone to breaking prop drivers, the old version had a tapered crank this one has a D type crank but the prop drivers have a little too much clearance leaving enough slack for a kick back to break the prop driver. I still have 2 spare prop drivers in my flight box from when I owned one. After breaking 2 I shimmed mine with a bit of beer can which seemed to solve the problem. I suggest you check the D in the prop driver for a crack in the corner.

[Denis Watkins]

Looking back and finding the absence of a thrust washer, with overtightening, the crank will have come forward

Making its rotation tight, and tapping with an hammer will have pushed the crank back hopefully to loosen things off.

Tapping will not have damaged the motor.

All should be well with the bits back in place as the motor is virtually run in now ready for flight.

[Martin Harris - Moderator]

Worst case scenario unless you used a sledge hammer is that there could be some microscopic flat spots on the bearings which could reduce their life a little.

[Scruffmeister]

Happily I found the thrust washer while getting the kids bikes out today. Test ran the engine in the garden - all good!

Thanks all - I'll hold my hand up to some first class muppetry

[Keith Berriman]

Well at least you found the washer and got the engine running smoothly. I find with my Irvine engines is to make sure you run them dry of fuel after a days flying. At home open throttle 10 drops after run oil close throttle and turn engine backwards 6 turns whilst nose up. Simple prime next time out and fires up first time (NB Use MT Formula Irvine 5% )

[cymaz]

Posted by RC Plane Flyer on 17/09/2017 20:33:12:

Well at least you found the washer and got the engine running smoothly. I find with my Irvine engines is to make sure you run them dry of fuel after a days flying. At home open throttle 10 drops after run oil close throttle and turn engine backwards 6 turns whilst nose up. Simple prime next time out and fires up first time (NB Use MT Formula Irvine 5% )

I always run my glow engines out of fuel until dry (2 and 4 strokes). A cc or two of MT after run and turn it over a few times. Not had any bearing issues for several years now. It's now just habit and is not a chore..think of it as good mechanical husbandry

[onetenor]

I'm glad it's sorted and need to say two things .First ! Next time you need to hit a threaded shaft bring the nut up level with the end of the thread so the blow does not damage the thread.Second! same occasion and need .Use a brass or ali drift between hammer and shaft to cushion the blow. Still with the nut at end of thread..Many an apprentice got clipped for forgetting this practice. Oh yes a third thing Keep the spare washer you should now have in a safe place.