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Author Topic: Petter PH Flywheel (not a gib key problem!)  (Read 9526 times)

Rxe

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Petter PH Flywheel (not a gib key problem!)
« on: February 20, 2012, 09:08:12 PM »
As I wrote the title of the thread, I had to add the comment about the gib key as I imagined most people would groan "not another stuck key".   This time it isn't a stuck key!

The engine is a PH1, pretty unmolested, down on compression and needing an overhaul.  I got it for not much more than scrap value on the 'bay, and I'm going to ovehaul the bits that need doing before it goes in my dump truck.   The dump truck engine is also down on compression, and is pretty unwilling to start on a cold morning. 

Anyway, I got a gib key puller, and with loads of WD40 and about a week of tension, it popped out.  Perfect. 

Except it isn't.  The flywheel is completely stuck solid.   I've tried walloping it with a leather mallet, I've tried jacking it off with a one of the big bolts on that side of the engine.    I've even warmed it with an oxy blow torch (warm is an appropriate word, that thing can absorb a lot of heat), and it isn't budging. 

So, what is the trick to getting a keyless flywheel off the crank?!?!

millman56

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Re: Petter PH Flywheel (not a gib key problem!)
« Reply #1 on: February 21, 2012, 07:27:06 AM »
Take off the cyl head, place a piece of wood 1" thick on the piston , replace the head and bolt up, rock the cranshaft back and forth, not too violently, the flywheel should move as the crankshaft comes to a dead stop, once the flywheel moves its all downhill from there.

Mark.

Rxe

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Re: Petter PH Flywheel (not a gib key problem!)
« Reply #2 on: February 21, 2012, 08:36:03 AM »
Ah, cunning.   Use the mass of the flywheel to help not hinder.   I need to take the head off anyway to work out why the compression is so poor.  And yes, I'll take the valves out first!

Thanks very much, will give it a try as soon as I have an hour with the engine!


listard-jp2

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Re: Petter PH Flywheel (not a gib key problem!)
« Reply #3 on: February 21, 2012, 09:56:58 AM »
Take off the cyl head, place a piece of wood 1" thick on the piston , replace the head and bolt up, rock the cranshaft back and forth, not too violently, the flywheel should move as the crankshaft comes to a dead stop.

That is one approach that could work, but if the flywheel does not show signs of moving and as millman56 points out don't get too violent with it, you could run the risk of bending the connecting rod.

If you still cannot get it to move after using the above method, then remove the the whole flywheel and crank assy from the crankcase, by undoing the ring of bolts holding the flywheel end main bearing housing to the crankcase. Once removed either use a large press to separate the crank from the flywheel.
If you don't have access to a large press then provide support to the flywheel, and using a suitable soft drift, and large hammer strike the end the of the crank to persuade it off.

Rxe

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Re: Petter PH Flywheel (not a gib key problem!)
« Reply #4 on: February 22, 2012, 08:40:41 AM »
I have a press, so if it comes to it, I can press the crank out.  I don't fancy stripping the engine with the flywheel attached though!

listard-jp2

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Re: Petter PH Flywheel (not a gib key problem!)
« Reply #5 on: February 22, 2012, 09:38:04 AM »
I don't fancy stripping the engine with the flywheel attached though!

Its not that bad, as all the nuts and bolts are reasonably easy to get to, you will however need to remove the crankshaft timing gear from the other end of the crank, so as to be able to withdraw the crank assy from the crankcase.

Rxe

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Re: Petter PH Flywheel (not a gib key problem!)
« Reply #6 on: February 27, 2012, 08:50:22 AM »
Update.  The block of wood between the piston and the head worked.  With the head off, I ran a suitable branch through the table saw, cutting off a 1" section.   Popped it between the head and piston and started gently swinging.  After about 2 minutes of swinging, I noticed that the gib key slots were out of alignment, and gradually it started to move more easily - loads of oil helped.  When it did come off, the mounting surface was not corroded, but it was huge  - there was no way that was coming off by conventional methods.

One thing I have noticed is that the small end bearing is loose in the conrod.  I have no idea whether it was loose before the flywheel swinging, or whether it was caused by the flywheel swinging, but it is worth checking.   I would imagine that the impact of flywheel swinging is not a lot compared to thousands of diesel explosions.

The low compression was due to a blown head gasket, and the rings were a bit sticky.  The bore is within tolerance and in good condition, so I will re-ring and deglaze.   Judging by the inch of sludge in the crank case, the oil was never changed from new.  Given that, the bearings are in remarkable condition, the big end is a bit scuffed, but the mains are clean.

One question: does anyone know how the main bearing at the flywheel end gets its oil?   The bearing has an oil hole in it, but there is no corresponding hole in the cover, and even if there was a hole in the cover, I can't see an obvious feed route for the oil.   The back (gear end) one is as expected, with bearing and feed holes aligned.

Edit: looking carefully at the cleaned up parts, I see an oil drilling in the flywheel bearing housing, and someone appears to have put the bearing in without considering this.   There is an oil flow to the bearing, but it is partial.   Pretty amazing that it is in such good order!
« Last Edit: February 27, 2012, 10:20:23 AM by Rxe »

listard-jp2

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Re: Petter PH Flywheel (not a gib key problem!)
« Reply #7 on: February 27, 2012, 11:49:03 AM »
One thing I have noticed is that the small end bearing is loose in the conrod.  I have no idea whether it was loose before the flywheel swinging, or whether it was caused by the flywheel swinging, but it is worth checking.   I would imagine that the impact of flywheel swinging is not a lot compared to thousands of diesel explosions.

It might be easier to fit a good condition s/h connecting rod, rather than try to repair what you have. Why not contact this ebay seller, as he is selling numerous parts from a PH2 engine: http://www.ebay.co.uk/itm/Petter-PH-cylinder-head-/170789948515?pt=UK_BOI_FarmingEquipment_RL&hash=item27c3dfcc63

Rxe

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Re: Petter PH Flywheel (not a gib key problem!)
« Reply #8 on: February 27, 2012, 04:16:54 PM »
I was thinking of putting a new bush in it?  I'll measure and see if it is actually out of spec.  If it is, as you say, a second hand part will be easier and cheaper - I already have one in a very dead PH.

Rxe

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Re: Petter PH Flywheel (not a gib key problem!)
« Reply #9 on: February 27, 2012, 05:34:07 PM »
Having checked the small end of the rod, it is 0.3mm out of round.  The book doesn't mention a spec for the rod itself.    There is no apparent damage to the rod, and I can't see how the flywheel whacking would have elongated the hole - as all the force would be directed to the base of the rod.  
« Last Edit: February 28, 2012, 07:26:36 AM by Rxe »