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ST2 Crankshaft Extension & Flywheel Removal


Lee Crook

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Hi All,

 

I've removed the LH150 gearbox and the drive gear from the extension but after hours of looking through the manual and parts booklet cannot figure out what I need to do next to remove the extension, fan, flywheel and casing. Here's a pic of where I'm at. Thanks in advance.

20221215_205523.jpg

Edited by Lee Crook
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The extension drive gear unbolts from the flywheel if I remember, its been a long time since I had a Lister ST3.  Then the crankshaft bolt  is revealed. The flywheel has timing balance marks that must be lined up on reassembly. The bolt is torqued to 300 ft/lbs, damn tight.

Slacken the bolt a bit only, then you need the special puller to pull the flywheel off the crankshaft taper.  Good luck.

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5 hours ago, matty40s said:

It might help to know what you are doing and why you think it all needs doing??

Hi, I'm doing a complete strip down, painting and rebuild of the engine. The boat had been sat in the marina for five years before I got it and water had got into one of the cylinders via the exhaust pipe and seized it up with rust. I've already removed and stripped down the cylinder heads and removed the cylinders, etc. The engine is forty years old and was in quite a state.

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3 hours ago, Tracy D'arth said:

The extension drive gear unbolts from the flywheel if I remember, its been a long time since I had a Lister ST3.  Then the crankshaft bolt  is revealed. The flywheel has timing balance marks that must be lined up on reassembly. The bolt is torqued to 300 ft/lbs, damn tight.

Slacken the bolt a bit only, then you need the special puller to pull the flywheel off the crankshaft taper.  Good luck.

Thanks, I'll give it a go later.

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5 minutes ago, Lee Crook said:

Thanks, I'll give it a go later.

Make sure you find the marks on the flywheel and I think on the casing, probably with one or the other pistons at TDC. Do line it all up before undoing the bolt, mark everything and be sure you can put it all back in the same place as the flywheel will fit on the crankshaft taper in any position and balance is critical on this engine, the flywheel is an off  center balance adjuster I think.

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The flywheel will only fit in one location, there's a Woodruff key in the taper. Td'A may be remembering SABB flywheels

 

The bolt that holds the flywheel on will be incredibly tight, you'll probably find it has been undone and done up with a large hammer and chisel in the past. Although crude, this works in the absence of a large socket. There's also a tab washer

 

Free the bolt off and unscrew it about a quarter of an inch (6mm). Then put the gearbox shaft back on - you'll find it won't go all the way home because it sits against the head of the bolt. Tighten the three bolts up and eventually there will be a bang and the flywheel will come off the taper

 

We have new flywheel bolts and tab washers if you want to replace them

 

Richard

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2 hours ago, RLWP said:

The flywheel will only fit in one location, there's a Woodruff key in the taper. Td'A may be remembering SABB flywheels

 

The bolt that holds the flywheel on will be incredibly tight, you'll probably find it has been undone and done up with a large hammer and chisel in the past. Although crude, this works in the absence of a large socket. There's also a tab washer

 

Free the bolt off and unscrew it about a quarter of an inch (6mm). Then put the gearbox shaft back on - you'll find it won't go all the way home because it sits against the head of the bolt. Tighten the three bolts up and eventually there will be a bang and the flywheel will come off the taper

 

We have new flywheel bolts and tab washers if you want to replace them

 

Richard

Thanks Richard, confusing my tapers! Its about 25 years since I played with a ST.

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Hi All,

 

Thanks for the replies, especially to Richard whose instructions were spot on!

 

Had to find a 2.5" socket with 3/4" drive. Got one off the shelf from a company just down the road in Chorley called Impact Socket Supplies UK. Then had to pop over to Machine Mart in Preston for a 900mm long 3/4" drive breaking bar. So now £105 lighter, fingers crossed it would work.

 

Got home and rushed straight out to check the socket would fit and it didn't despite it being shown on the bolt.

 

20221216_205128.jpg.ae6da4857e262ce1a9eb57c5418109ec.jpg

 

Upon closer inspection it was clear that the bolt didn't have parallel faces and the faces all sloped inwards towards the flywheel so I got out the gauge and checked the dimensions. I then decided to use the 90 degree die grinder with a scotchbrite pad attachment to gently square up all the faces of the bolt.

20221216_203148.jpg.e7e54757f58e57c6edcf3723e3cbd597.jpg

 

Eventually, after about an hour of fettling the socket went on with a little gentle persuasion! Prior to this I had flattened the washer with a chisel. I used a 6" block of wood to stop the shaft rotating and with decent amount of pressure on the 3ft breaker bar the bolt came loose but was stuck tight in the socket.

 

20221216_203734.jpg.46677d2243963da8ef2abc8e3c8a503d.jpg

 

So I sat the socket on two blocks on wood and used some round bar to tap out the bolt.

 

I then put the bolt back in to the shaft until is about 6mm shy. I then took the shaft extension and nipped up the three bolts evenly.

 

20221216_204230.jpg.41c022ae7633fb76c1c56ec636417b82.jpg

 

I moved from bolt to bolt and just added 1/4 turn to each until the flywheel came free and I was able to remove it.

 

20221216_204434.jpg.b475622232f7a113b4eb6e0bc3f0cb0c.jpg

 

 

Edited by Lee Crook
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Oh, probably. That end can be a mystery because it often has non-standard pulleys fitted. As yours has

 

The little one looks like it is for a bilge pump, check to see if it has an Allen grub screw somewhere in the side.

 

As an example of 'customisation', you engine has had the camshaft cut short

 

Richard

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