How to get the dog clutch off the crankshaft nose

[Anonymous]

Just an update: today we took the old engine out of the boat, and started swapping the marine bits on to the new engine. But we hit a snag...

How do i get the dog clutch off the crankshaft nose on my marine engine?
We heated it with a soldering blowtorch for 10 minutes, but that didn't help. Any ideas?

joel510 said all i need to do is heat it:

I think you'll find the cranks are the same. Most of the long motors in ski boats were unmodifed car engines with marine kits.
I have an EFI X-flow in my boat that also drives from the front of the engine with a dog clutch.
It uses a dog gear which is grub screwed to the crank. You'll have to heat it up to remove it though as they're heated up to fit. I know both the Tawco and Rolco marine kits use this method with their dog clutches.
Your best bet would be to replace the short engine. It'd be the cheapest and most hassell free IMO.

 

[xdee]

Maybe a stupid question but did you remove (or loosen) the grub screw?


.

 

[joel510]

Hmmm... Yeah they are a real pain to get off. I haven't removed one for a while. They are designed to be sort of an interference fit so it will have to be heated evenly and quite hot. You may need an oxy to do it.
When you refit it, heat it in the oven to around 200C then fit it really quick to the crank or it'll get stuck half way.
Have fun, Joel.

 

[L6]

How do i get the dog clutch off the crankshaft nose on my marine engine?
We heated it with a soldering blowtorch for 10 minutes, but that didn't help. Any ideas?

These are interference fit on the crank. During installation the clutch is heated in an oven so it expands then is slid over the cold crank and shrinks on tight. The problem during removal is that heat applied to the coupler transfers through to the crank so they both expand together.

I am assuming you have removed the crank from the block. Buy a couple of bags of crushed ice, pack the ice around the crank close to the coupler and leave it until the whole assembly cools down. Apply heat rapidly to the clutch using an oxy torch with a large tip and soft flame. As soon as the crank starts to warm up stop applying heat because it will not help and restart the operation.

There is a good chance you will not get the clutch off by yourself and will have to take the crank to an engineering shop with a large press. It will take them about a minute to pop it off.

 

[addo]

Would a decent sized puller work? The ones with hinged arms, like a gear puller.

You could probably chill the crank a little by squirting liquid gas down the bolt hole if it's accessible.

Of course, that would evaporate pretty smartly when you lit the oxy. You're not in the West are you? I could send you to a mate in Merrylands, or another guy in Toongabbie; both with presses.

 

[Anonymous]

Yes, i took the grub screws out.
No, i haven't removed the crankshaft.
I'll give it more of a go today, i bought a gear puller with the hinged arms so i'll see if that helps, with a bit of help from a torch.
If i can't get it off, i'll take the crank out and take it to an engineering shop. I'm in the castle hill area, so i'll ask around down in the industrial estate.

 

[Anonymous]

Well, just an update, all the marine mounts are repainted and bolted on to the new block. And FYI, it ALL fits, bolt-for-bolt, which is quite nice considering this is a crossflow and the old one was a 250 2v

 

[Anonymous]

I'm also toying with NOT running a water-cooled manifold. Is this such a huge sin? Its not like i'm racing - i'm only wakeboarding at 2000 rpm.
Whats your opinions - do you think i could get away with it?

Here are some of the quotes for a lousy watercooled exhaust manifold i got:
Moby: $630
Luxfords: $544
Cassell: $648

 

[joel510]

Here you go chubs. One attached to this motor on Ebay.
http://cgi.ebay.com.au/ford-250-cro...80021033QQcategoryZ26451QQrdZ1QQcmdZViewItem
I think the main issue with the manifold is for safety. Keeping temperatures low.
Joel

 

[L6]

Here you go chubs. One attached to this motor on Ebay.
http://cgi.ebay.com.au/ford-250-cro...580021033QQcategoryZ26451QQrdZ1QQcmdZViewItem
I think the main issue with the manifold is for safety. Keeping temperatures low.
Joel

That one is for a flywheel drive, chubs has a snout drive. Unless the manifold bolt holes are symetrical allowing the manifold to be installed upside down it will discharge into the boat.

If you want to run an engine cover, the manifold must be water cooled. The amount of heat given off is enough to start fires.

The only way to avoid a water cooled manifold is to run the engine completely open and have the pipes pointing upwards racing style. It will be very economic to run --the noise will be so bad you won't use for more than ten minutes at a time.

 

[joel510]

It's the same as mine. Mines snout drive too.
They're designed to be mounted either way.
Joel

 

[Anonymous]

It's the same as mine. Mines snout drive too.
They're designed to be mounted either way.
Joel

Oh crap. I saw that auction before but deliberately didn't bid on it because it's mounted the wrong way around - and now i check the forum and you tell me "they're designed to be mounted either way"... are you serious? they can go either forwards or backwards?
DAMN! missed out. :x

Oh well - UPDATE:
Took the old crank to a mechanic who popped the dog gear off for me, for the grand sum of $40.
I'll have to ring around and see if i can find someone to bash/weld the old (watercooled) sump back into shape for me. Its got a couple of conrod-shaped holes in it - have a look



Also, any tips for putting the dog gear on to the new crank? My idea (As suggested before) is to chuck it in the oven for half an hour, take it out, spray the crank nose with WD-40, slip it onto the keyway a tiny bit, then put a bit of wood up against it and BANG whack it on quick with a sledgehammer. Ouch my poor thrust bearings!

 

[L6]

It's the same as mine. Mines snout drive too.
They're designed to be mounted either way.
Joel

Oh crap. I saw that auction before but deliberately didn't bid on it because it's mounted the wrong way around - and now i check the forum and you tell me "they're designed to be mounted either way"... are you serious? they can go either forwards or backwards?
DAMN! missed out. :x

Most of the 6 cyl manifolds are designed to go either way, and most of the V8 manifolds are designed to go on either side by moving the blanking plate.

Also, any tips for putting the dog gear on to the new crank? My idea (As suggested before) is to chuck it in the oven for half an hour, take it out, spray the crank nose with WD-40, slip it onto the keyway a tiny bit, then put a bit of wood up against it and BANG whack it on quick with a sledgehammer. Ouch my poor thrust bearings!

The main thing is to be fully organised before starting.

Check the mating surfaces of the crank and dog are free of any burrs.
Turn the crank so the key is facing upwards.
Mark the outside of the dog in line with the keyway to assist starting it on the crank.
Heat the dog in the oven
While the dog is heating pack crushed dry-ice around the crank nose

When ready, quickly take the dog from the oven and turn it so the key mark is upwards then slip it onto the nose of the crank.

It should slide on without much drama and certainly should not require a sledgehammer IF YOU ARE QUICK. If it becomes difficult to move then you have to keep it going with brute force or go through the drama of removing it and starting again. So have a heavy persuader close by just in case it is required because speed is all important.

I have seen people place big G clamps against the face of the flywheel and the mounts on rear housing to squeeze the crank forward supposedly to take the impact of any hammering and save punishing the thrust bearings. My guess is that there is enough spring in the G clamps they have little effect.

As indicated above, plan it out, get organised, and once you start be quick.

 

[Anonymous]

Thanks, i'll let you know how i go.