Remove flywheel

[lustyd]

Hi all, can anyone tell me how to remove the flywheel on a mariner 4hp? Here is the diagram. I removed the bolt but couldn't get the flywheel off. I didn't try much force just in case
Thanks
Dave

 

[30boat]

You probably need a flywheel puller that screws into the flywheel and has a bolt that once screwed in pushes it out.Is there a thread on the flywheel central hole?

 

[lustyd]

No idea I haven't looked but will this weekend. Where do I get a flywheel puller?
Thanks
Dave

 

[PaulJS]

There's most likely a locating key in the morse taper to ensure correct positioning when re-assembling, and to reduce the remote chance of the flywheel slipping relative to the crankshaft, but it's ALWAYS a good idea to mark its position on the crankshaft BEFORE disassembly!

That is assuming the engine is, or has been a runner recently...

 

[VicS]

The puller you need is called a "harmonic balancer puller"

Google will show you what they are

It bolts to the flywheel using the three tapped holes you can see and high tensile bolts.

The central bolt bears on the end of the crankshaft.
Tighten it down and then give it a smart knock with a decent sized hammer.

If possible leave the retaining nut #6 on but slackened

Yes there will be a Woodruff key ( see the cylinder block/crankshaft diagram) It locates the flywheel when refitting


Note the key fits with its straight side parallel with the axis of the shaft, not with the taper.

Be sure to tighten the retaining nut to the correct torque If you leave it too loose the key can shear off It is not designed to transmit the drive, only to locate the flywheel correctly.

 

[lustyd]

Thanks guys, is This sufficient? There are alternatives going all the way up to £80 but I'd prefer the cheaper option if it'll be OK.

I've looked in the owners manual and the only mention of torque was for the skark plug. Does this mean I need the workshop manual or is the info available elsewhere?
Thanks again
Dave

 

[VicS]

That ought to do it.

You might need to source bolts with the correct thread though. They might be an American thread ( UNF)

cant help with the torque. It's 40lbsft for my Evinrude IIRC.

You could try asking on the Mercury Mariner board of the iboats forums what the correct torque is.

 

[lustyd]

Thanks Vic I'll order one of those. It's just occurred to me that I could ask the man at the Emsworth marina shop who I suspect will know the number too

 

[VicS]

out of interest why are you removing the flywheel?

 

[smonard]

There's most likely a locating key in the morse taper to ensure correct positioning when re-assembling, and to reduce the remote chance of the flywheel slipping relative to the crankshaft, but it's ALWAYS a good idea to mark its position on the crankshaft BEFORE disassembly!

That is assuming the engine is, or has been a runner recently...

There is the bodger route, loosen the nut a few turns then get someone to hold the motor by the flywheel then give the top of the nut a sharp rap with a hammer. It'll probably just pop off. It would be prudent to use a brass hammer or a bit of hardwood on top of the nut.

 

[lustyd]

out of interest why are you removing the flywheel?

Mainly because I never have before. I have no experience of the magneto and various electrical parts and would like to learn before I need to so I figured I should have a go.

I tried previously and failed at pulling it off, hopefully I've not done any damage by getting the torque wrong on the nut.

 

[vyv_cox]

What torque? Overtightening a taper joint can make it extremely difficult to release. It's normally not necessary to give it much more than a nip.

 

[VicS]

Mainly because I never have before. I have no experience of the magneto and various electrical parts and would like to learn before I need to so I figured I should have a go.

I tried previously and failed at pulling it off, hopefully I've not done any damage by getting the torque wrong on the nut.

Dont bother then! There are only a couple of coils under there which are not likely to need any attention.

It would be different if there were points under there that need an occasional clean and reset.

As Vyv says dont overtighten the nut but at the same time it must be tight enough so that it cannot slip.

Find out the correct figure .
I may have remembered the figure for my Evinrude wrongly. I have never taken the flywheel off and have no intention of doing so, least ways not without good reason.


The removal method suggested by smonard may work if there is sufficient flywheel exposed to get a good grip on.
It is the method by which flywheels are removed from Seagulls.

 

[peteK]

Mainly because I never have before. I have no experience of the magneto and various electrical parts and would like to learn before I need to so I figured I should have a go.

I tried previously and failed at pulling it off, hopefully I've not done any damage by getting the torque wrong on the nut.

I removed mine on a mariner 5 with a home made puller,to fit a lighting coil to charge the battery .The holes on the flywheel are metric thread,I wouldnt remove for the sake of it as most of workings can be seen through the slots.If you do remove it place keeper bars across the magnets if you dont replace it straight away.

 

[Lakesailor]

I made a lash-up puller from a 3 legged puller to take my Tohatsu/Mariner/Mercury/Nissan flywheel off.
Only because I was replacing a main bearing.
I wouldn't bother unless there is work to do under there.

(The large black bracket was a chassis bracket from a 4x4 removed when fitting a tow bar. Nothing significant in the shape)

 

[lustyd]

It would be different if there were points under there that need an occasional clean and reset.

Thanks Vic, useful as always! I wasn't aware there were no points to clean and had read somewhere that was sometimes necessary. Does that mean therefore that there is less to go wrong with the electrics on this one?

 

[Jim@sea]

Pour boiling water on it, metal expands, the centre wont expand. Its worth a couple kettle fulls to try it. Could try and carefully use a blowlamp. You could also hang the outboard upside down and start tapping the flywheel. Perhaps when I was an apprentice in a Garage in the late 50's people used cruder methods than today but they work. Its not unknown for people to use a welding torch on outboards as I saw when I went to one of these well known Outboard Motor dealers recently and they were using a welding torch on the bottom end of an Outboard. What suprised me is that they were doing it alongside the path where customers would walk to get into the showroom. Anyway good luck

 

[VicS]

Thanks Vic, useful as always! I wasn't aware there were no points to clean and had read somewhere that was sometimes necessary. Does that mean therefore that there is less to go wrong with the electrics on this one?

You have not said exactly what (age) model but you posted a link to parts diagram at the start of the thread.

It shows an an electronic ( CD) ignition system ........ no points !

 

[lustyd]

You have not said exactly what (age) model but you posted a link to parts diagram at the start of the thread.

It shows an an electronic ( CD) ignition system ........ no points !

Hehe these things must be so obvious when you know what you're looking at I take it that the electronic system is fairly maintenance free then? It's a Mariner 4HP Sailmate 1996.

 

[VicS]

Hehe these things must be so obvious when you know what you're looking at I take it that the electronic system is fairly maintenance free then? It's a Mariner 4HP Sailmate 1996.

If any part fails is most likely to be the CD unit or perhaps the HT coil. Failure of the parts under the flywheel is not very likely.