Crank appears to be seized on a forty plus model??

[MorrisMan]

Hello, new to the forum. I have just purchased my first seagull for £15 at a car boot sale. From the website ID tool it is a forty plus model from April 1966. It is fitted with the Bing carburetor.

Initially it appeared to have a seized piston, as it is not possible to turn it, even with a big spanner on the dome nut. However having separated the cast iron block from the main alloy housing, I can pull the block away from the housing about 1/2", and the piston moves up and down in the bore. It appears that the crank itself will not rotate. The dome nut looks at a slight angle, I wonder if it has been dropped and the crank is bent. The propshaft wiggles very slightly so I do not think it is seized at that end.

It has the Bing carburetor, with a plastic float chamber, does this tend to run well or should I consider swapping it for the villiers? The air filter and choke flap is missing.

A few bolts will not come free so I am soaking it for a few days and will try some gentle heat from a blow torch. The head bolts came out very easily as they appear to have been replaced with stainless ones.

The head gasket appears to be four layers of copper, is this normal??

SeagullOutboard 2.jpg (181.88 KiB) Viewed 729 times

Thanks for your advice. As you can see from the photos I have a few parts to source. I have a little experience with classic cars restoring SU carburettors, so I am hoping I can get this seagull up and running.

[chris]

I don't think the bing carb is standard for that model, they were used for a short time in th 70's model,
does the gearbox turn at all as it could be siezed and that could be the problem

[MorrisMan]

I have removed the lid of the gearbox, and I can rotate the prop shaft slightly, sounds like just the clearance in the gears. I can also push the pro shaft back and forwards slightly along its length. There was sludge in the gearbox, but it was quite soft so do not think that end is seized. I have not been able to undo the countersunk screw that holds the gearbox on yet. If the gearbox was seized would the dome nut rotate a little bit? It seems completely solid.

[Hugz]

If it is the gearbox you would be able to rock the flywheel. Does sound as though it is seized at the crankshaft. Unusual.

[MorrisMan]

OK I took another look at it today, I slackened the bolts that clamp the two halves of the crankcasing together, and hey presto the crank will now rotate. As it rotates, a gap opens and closes inbetween the two crankcasing halves, up to about 3mm at the widest point, and then closes completely. The flywheel sounds like it is catching slightly at one point as it is rotated. To me this all suggests the crank itself is bent significantly.

What material is the crank likely to be on a 40+ model? I may have a go at trying to straighten it, what are my chances of straightening it to within suitable tolerances? I fear it may be a lost cause and I will have to find a replacement. Always a shame when you have to throw away a genuine part.

I am going to remove the propshaft to clean out the gearbox, I can see a brass collar with a pin through it behind where the prop would be. Is this a straight pin that I can tap through from either end or is it tapered?

Thanks for your time.

[Horsley-Anarak]

Bent crank, replacements are readily available, and cheap.

Or you can have a go at straightening it.

Post some more pictures, we all like a few pictures.

You will need to do a total strip down to see what else is damaged, in the power head.

It sounds like it may have been for a swim.

They can be straighten easily if not twisted.

H-A

[MorrisMan]

Yes I think a complete strip down would be wise. The dome nut looks like it was hit hard, the thread is bent as it exists the dome nut. I think this will require straightening aswell.

What level of runout can I get away with? and to straighten it, tap it with a soft mallet? any heat? I have yet to remove the crank. If I can get it out over the next few days, I am visiting someone with a nice lathe and a dial gauge which would be useful.

[Horsley-Anarak]

What level of runout can I get away with? and to straighten it, tap it with a soft mallet? any heat? I have yet to remove the crank. If I can get it out over the next few days, I am visiting someone with a nice lathe and a dial gauge which would be useful.

You will not need heat, give it a bash with a mallet, I managed about 1.0 thou, you will know when it is near enough when you get it back in the crankcase.

If the crankshaft is twisted or crankcase is distorted it may be harder to sort out.

Good luck, I have straightened a few and they work perfectly.

You can always pop a 5/8" reamer through the assembled crankcases if you think it is a bit distorted. Worth trying before looking for a new crankcase.

H-A

[Hugz]

I've been wacking a flywheel with a lump hammer which has about a 2mm discrepancy (the flywheel/crankshaft that is). So far no improvement. I do know that the shaft bent after the motor took a tumble, even landing on carpet. Leaning motors and drunken women don't mix.

I do have many spare flywheels

[MorrisMan]

I hope I do not need to get as close as 1 thou. Also as you have pointed out, if my casings are distorted it will not run true even if straightened.

I am struggling to remove the chrome plated exhaust tube, it has one small screw that attaches it to the block, it does not appear to have any other fixings. Is it only the one screw holding it on?

[bikerboyfife]

Yip one screw then move from side to side it will come,,,,

[Keith.P]

You do also have a copper water pipe that is running down the inside of the exhaust and that will sometimes not pull apart from the base, soft hammer time.

[MorrisMan]

I have given the exhaust tube a bit more grief but only grazed knuckles to show for it. It is difficult to grip well. I have yet to undo the countersunk screw securing the gearbox either.

I will try some heat on the tube and the gearbox screw next. Is the brass pin in the prop shaft spindle a straight one or tapered?

[Hugz]

Jon made a good suggestion a while back. Bolt a drive tube back on and use that to hold block steady while rocking the tube. Or could you re bolt on existing driveshaft/gearbox 180degrees ie so exhaust tube is unencumbered. Haven't tried myself but sounds good in theory.

A little later: Yep driveshaft and gear box fits backwards.... Mmmmm, getting crazy ideas

Pin is straight.

[headdownarseup]

Sounds to me as though the bottom of the exhaust tube has corroded to the pump housing. No wonder your having trouble getting it to move? (bruised/grazed knuckles are not to be taken lightly either)

Dont try and remove the gearbox/pump housing just yet. Concentrate on the exhaust tube first of all. (it will make sense later on)
Firstly remove the little screw that holds the tube to the block.(dont loose the screw) Next arm yourself with a blowtorch and CAREFULLY heat the tube at the bottom just enough to get it rotate a little bit. (this is where you'll curse and swear at it) If the tube is aluminium try not to melt it, a brass tube will take a bit more abuse but it will tarnish the chrome a bit, but you need to take it apart to see what's going on inside the crankcase.
Next is the difficult part of trying to get it to move downwards(whilst it's still hot/warm) over the outlet of the pumphousing.The reason for this is so you can undo and remove the water feed pipe that goes into the base of the block.(it sits almost at the top of the exhaust tube)
With the exhaust and waterpipe detached the powerhead should seperate from the lower unit fairly easy (famous last words!) It might get a bit sticky on the square drive shaft inside the torque tube.

Some of these seagulls will be quite well corroded if they havn't been apart in many a decade, especially if they've been sat in a damp shed or garage for years?
Keep at it, i'm sure it will come apart eventually.

A rubber hammer and a lump of wood will sometimes work but be carefull where you place the force of the impact. Cast iron can sometimes crack and cast aluminium will break quite easy if you're careless.

Then you can play with rusty nuts and bolts in the gearbox? (heat is your best buddy and sometimes more than you think when it comes to seagulls)

best of luck

jon