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ASP prop driver stuck!

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Keith Miles 210/08/2019 01:08:24
170 forum posts
6 photos

In another thread about problems with air in the fuel line, I reported that, as the thread originator had done, I too managed to cure the issue by fitting a sintered bronze filter clunk.

I decided to then leave the cowl off until I had done a few test flights.

The engine is an ASP FS80. The cowl has been off on a number of occasions previously requiring, of course, removal and refitting of the prop and spinner.

Recently, having completed the test flights and with the engine nicely set up, I removed the spinner and prop, refitted the cowl, then refitted the prop and spinner following which I was unable to turn the engine over by hand!

It was quickly determined that the rear face of the prop driver was hard against the crankcase despite me having seemingly tightened the prop no more than I usually do.

To cut a long story short, despite my best efforts with releasing oil, puller and a heat gun, whilst I have thus far finally been able to restore rotation, I cannot get the prop driver off!

I note, from the parts diagram, that there appears to be no thrust washer between the front bearing face and the split tapered cone securing the prop driver to the crankshaft and am wondering if this has caused the prop driver to move further back, on this occasion, than normal leaving no clearance between it and the crankcase.

Purely out of curiousity, I was wondering if anyone else has had this experience?

My OS engines have thrust washers, albeit no tapered cone arrangement, similarly my Irvine two strokes, the former using woodruff keys and the latter having flats on the crankshaft.

I also have a brand new, yet to be run, Saito 62B which also has a split tapered cone and, notably, looking at the drawing, no thrust washer either.

Needless to say, I am now concerned about how best to judge tightening of the prop nut where a tapered cone is used in order to avoid a repeat of this experience!

Any bright ideas for getting the prop driver off would also be appreciated!

Braddock, VC10/08/2019 01:27:05
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1632 forum posts
82 photos

From machine mart, battery/windscreen wiper puller about £10puller on saito 82.jpg

cymaz10/08/2019 07:55:06
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8648 forum posts
1175 photos

I have one of THESE....essential in my workshop

Solly10/08/2019 09:23:27
241 forum posts
1 photos

I note you have already tried a puller. This happened to me also, The heat gun was not adequate so I carefully used a propane torch on the prop driver and that did the trick.

alex nicol10/08/2019 10:14:23
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285 forum posts
13 photos

I could be off the mark here, from memory I think the ASP also has a woodruff key that locates the prop driver?

I have something niggling in the back of my mind that if this key drops out jammed prop driver or slipping prop position can occur.

I tried to check the Just Engines Website for parts diagram before posting but its down for maintenance at the minute.

Agree with Solly, sounds like you might need to use a hotter heat source to get the driver off

Good Luck

Alex

Martin Harris10/08/2019 10:31:33
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8793 forum posts
215 photos

I don't know what sort of puller you've used but the most effective way to shift a stuck taper is to tighten the extractor and give the forcing screw a sharp tap with a hammer, assuming it is substantial enough to transmit the shock.

P.S. I've just checked my 180 and it definitely uses a Woodruff key AND a thrust washer between the bearing and driver.  Omitting this WILL lock the engine.

P.P.S. Just spotted that yours is an 80, not a 180...you can easily check whether yours has a key though as with the nuts and washer removed the keyway will be easily seen.

 

Edited By Martin Harris on 10/08/2019 10:46:58

Keith Miles 210/08/2019 14:40:01
170 forum posts
6 photos

Thanks for your responses, guys, much appreciated!

Taking points in order....

Might check out the windscren puller, (see puller comment below!) not seen one of those before! Ta!

Don’t have a propane torch but at least it’s somewhat comforting (if that’s an appropriate word) to know that my experience is, indeed, not unique! Will park that one for the time being but it certainly says something! Crikey!

Found my ASP parts diagram and, like the Saito, tapered split cone, no thrust washer.

Have tried two different pullers of the automotive variety, the first, a borrowed small three-leg one and a subsequently purchased larger two/three leg one (which just cost me £30 yesterday from Halfords!). In both cases because I couldn’t get the legs securely under the lip of the prop driver, I borrowed a purpose made “U” shaped piece of 4mm steel which slides into the driver groove. Both pullers, small three-leg and large two-leg, merely bend the plate upwards!

Had already tried the old “tapping the extractor screw with a hammer” trick. No joy.

So, to my second question regarding the tightening of the prop nut.....

Where a prop driver is secured by some form of key or machined flat on the crankshaft (e.g. my Irvine and OS engines) and a thrust washer sits between bearing and prop driver, it would seem impossible for the prop driver to jam against the crankcase, indeed, with prop removed, the prop driver is more likely to just fall off possibly together with the thrust washer and any woodruff key!

Conversely, it would seem that with a tapered cone, the situation is quite the reverse!

In the latter case, it would seem to me that the only thing preventing the prop driver moving too far back and fouling the crankcase is the nature of the initial machining tolerances and lack of wear over time in respect of both the tapered cone and the prop driver. It also seems to me that it wouldn’t be practical, whilst tightening a prop nut, to have to check crankcase/prop driver clearance with a feeler gauge although that might seem to me to be, at present, the only solution to avoid repeating the experience!

Oh, and I only use a standard size spanner and I’m not Charles Atlas! smiley

And if, or when, I manage to get the prop driver off, I am currently of a mind to replace both it and the tapered cone provided I can track down the apparently now elusive spares!

Edited By Keith Miles 2 on 10/08/2019 14:45:18

jrman10/08/2019 15:10:31
348 forum posts
3 photos

just "tapping" the puller may not be enough. It may need a hefty whack!

When you do get it apart check that there is nothing e.g. grit of similar dirt in the slot of the collet. This would prevent the collet closing up and gripping the crankshaft. I found this was the problem on a friends Saito (if I remember correctly) which was proving almost impossible to tighten up the prop.

Edited By jrman on 10/08/2019 15:11:30

Martin Harris10/08/2019 15:18:24
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8793 forum posts
215 photos

This is what I use (bearing separator) and no engine has ever given more than token resistance to its efforts:

20171001_115601.jpg

One day I might find a better piece of steel for the bridge piece but it's always worked so far.

It's difficult to see how enough wear would occur to close up the tolerances enough to lock the engine.  Are you sure there's no washer supposed to be there?  Although my keyed 180 has one, I didn't see one shown in the parts diagram when I checked earlier...

Another thought, if you have a "proper" motor engineer nearby, they could use a similar tool in a hydraulic press - or if desperation sets in, you could split the prop driver with little chance of damaging the crankshaft. Either use a "nut splitter" or hammer and chisel...

What part of the world are you in?  Someone might be able to assist...

Edited By Martin Harris on 10/08/2019 15:36:05

Keith Miles 210/08/2019 15:26:15
170 forum posts
6 photos
Posted by jrman on 10/08/2019 15:10:31:

just "tapping" the puller may not be enough. It may need a hefty whack!

When you do get it apart check that there is nothing e.g. grit of similar dirt in the slot of the collet. This would prevent the collet closing up and gripping the crankshaft. I found this was the problem on a friends Saito (if I remember correctly) which was proving almost impossible to tighten up the prop.

Edited By jrman on 10/08/2019 15:11:30

Rest assured, I gave it a decent, albeit judicious “whack” with a copper headed mallet, in fact, it has had several, spread out over several hours, gradually increasing the tension on the puller and with regular application of a heat gun.

Also, my problem is not one of tightening the prop but, if anything, one of perhaps having overtightened it and perhaps pushing the prop driver back too far, as has been previously fully explained in this thread.

jrman10/08/2019 15:31:58
348 forum posts
3 photos

If the collet had grit in the slot it would not have tightened up on the shaft and would have just moved towards the crankcase until it could go no further. Exactly the symptoms you have described.

Keith Miles 210/08/2019 15:48:48
170 forum posts
6 photos
Posted by Martin Harris on 10/08/2019 15:18:24:

This is what I use (bearing separator) and no engine has ever given more than token resistance to its efforts:

20171001_115601.jpg

One day I might find a better piece of steel for the bridge piece but it's always worked so far.

It's difficult to see how enough wear would occur to close up the tolerances enough to lock the engine. Are you sure there's no washer supposed to be there? Although my keyed 180 has one, I didn't see one shown in the parts diagram when I checked earlier...

Edited By Martin Harris on 10/08/2019 15:26:22

Thought about that method, but there is currently only a few thou gap between prop driver and crankcase so probably would not be able to get that in even if I had one.

I am also puzzled as to how this problem suddenly arose (having had the prop off on numerous occasions) as are a number of my fellow fliers and yes, according to the exploded parts diagrams for both the engine in question and the Saito I have, there is no thrust washer.

Needless to say, I am not persuaded to try to remove the prop driver on my, as yet, un-run brand new Saito as well to see if the drawing is correct!

Then again, it seems to me that if both taper and prop driver are correctly machined to prevent the prop driver moving too far back on the crankshaft and, as you say, wear would be unlikely to be sufficient to create a problem, then a thrust washer would not be necessary.

CARPERFECT10/08/2019 15:53:58
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483 forum posts
7 photos

There is no woodruff key on the fs80

Martin Harris10/08/2019 16:01:04
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8793 forum posts
215 photos

Agreed - I've just pulled the driver off a spare 90 and there is also no washer involved behind the taper collet.

Keith, is there any clearance between the back of the driver and the crankcase? Checking the 90 driver with the collet removed showed that it goes all the way back flush so if there is any gap, it probably isn't the driver binding against the casing - maybe some foreign object has got trapped in there?

P.S. Just noticed you'd answered these questions while I was pulling drivers!

Edited By Martin Harris on 10/08/2019 16:06:34

Martin Harris10/08/2019 16:05:20
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8793 forum posts
215 photos
Posted by Keith Miles 2 on 10/08/2019 15:48:48:
Posted by Martin Harris on 10/08/2019 15:18:24:

This is what I use (bearing separator) and no engine has ever given more than token resistance to its efforts:

20171001_115601.jpg

One day I might find a better piece of steel for the bridge piece but it's always worked so far.

It's difficult to see how enough wear would occur to close up the tolerances enough to lock the engine. Are you sure there's no washer supposed to be there? Although my keyed 180 has one, I didn't see one shown in the parts diagram when I checked earlier...

Edited By Martin Harris on 10/08/2019 15:26:22

Thought about that method, but there is currently only a few thou gap between prop driver and crankcase so probably would not be able to get that in even if I had one.

No no no! Please don't think I was suggesting levering it off!

It fits into the machined groove in the middle of the driver.  Tighten the bolts and if it doesn't pop off easily, strike the bar smartly over the prop nut...

Edited By Martin Harris on 10/08/2019 16:08:35

bert baker10/08/2019 16:22:27
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1423 forum posts
303 photos

Have you tried knocking it on further with a deep socket or bit of tube

Martin Harris10/08/2019 16:54:24
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8793 forum posts
215 photos

Re-reading the OP it has just struck me that there was no mention of removing the driver at any time. This deepens the mystery a little and leads me to start wondering about a bearing or crankshaft failure...but I'm struggling to work out quite what could have happened?

Keith Miles 210/08/2019 17:07:48
170 forum posts
6 photos
smileyPosted by jrman on 10/08/2019 15:31:58:

If the collet had grit in the slot it would not have tightened up on the shaft and would have just moved towards the crankcase until it could go no further. Exactly the symptoms you have described.

No, not what I described at all if you read my posts.

I am not talking about the cone/collet being too far back but the prop driver (the shiny serrated round silver coloured thing) that fits onto the collet/cone.

Grit in the collet slot would create the opposite problem to the one I have described because it would (a) prevent full compression of the cone/collet preventing it from tightening fully onto the crankshaft and (b) it would consequently prevent the prop driver from being fully drawn onto the taper.

So grit in the slot would, of course, result in a loose propellor/prop driver/ tapered collet assembly that you wouldn’t be able to tighten sufficiently resulting in loss of drive between crankshaft and prop and totally contrary to my scenario you would have no difficulty at all turning the prop by hand even if the piston didn’t go up and down!

So, to recap, my engine jammed solid and could not be turned by hand because, on inspection, it was found that the rear face of the prop driver was hard against the front bearing housing so that I was unable to turn the prop by hand by even a degree.

If you read my posts, you will note that I have been describing a jammed engine and its aftermath and never a loose prop assembly!

Good to know that everybody else got it, though.

smiley

Keith Miles 210/08/2019 17:10:45
170 forum posts
6 photos

How does one delete a post?

Do I need Specsavers?

Edited By Keith Miles 2 on 10/08/2019 17:17:22

Alan Gorham_10/08/2019 17:14:05
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940 forum posts
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Posted by alex nicol on 10/08/2019 10:14:23:

I could be off the mark here, from memory I think the ASP also has a woodruff key that locates the prop driver?

Alex

Someone did....

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