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Early 80's BF75 flywheel won't turn

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FishyBC

Contributing Member
Hello,
I acquired I believe a 1983 BF75 7.5 hp that had a ton of work done on it. The owner gave up on it.
I spent a few mins last night and saw that I could not pull the pull start. I popped the plugs out and still cannot move the flywheel.
I had a look and see clean oil on the dipstick.
Is this a boat anchor or is there anything someone can recommend that might help me get it moving again ?
My first 4 stroke and I'd love to give it a try if I can get it going.
Thanks
 
Water in the lower unit ?-----Frozen perhaps ?-----Picked up a like new 15 HP Suzuki 4 stroke last week.---Stuck from sitting perhaps.-----Will find out once I take it all apart for a look see.---Dealers are not interested in this type of work.
 
racerone said:
Water in the lower unit ?-----Frozen perhaps ?-----Picked up a like new 15 HP Suzuki 4 stroke last week.---Stuck from sitting perhaps.-----Will find out once I take it all apart for a look see.---Dealers are not interested in this type of work.
Click to expand...

Thanks Racerone, I will check this when I get home but while freezing here currently, it's right around the freezing mark and my garage I don't think is quite below freezing.
I'm going to pull the starter off it tonight to insure that isn't the issue but I'm so hoping it's something simple. It is a super clean motor and one I would keep if I can get it going.
 
I am suggested it might be ice in the lower unit.----I am not there to know what the motor looks like or to judge the local atmospheric conditions !!
 
Last edited:
Well, you may find that it is, indeed, the starter mechanism. So I agree with taking it off and seeing if you can move the flywheel.

If it's still stuck and it's not the lower end frozen or bound up, you can pull the valve cover and the flywheel to investigate further.

But if you have one of those little flex cameras that plug into a smart phone ($20 on Amazon), you can take a look at the cylinder walls with that. If it's a bent rod there will be bad scores in there.

These little outboards are pretty prolific and there are many, many parts motors out there. Easy to work on and usually worth the trouble if you can get one going.

Good luck!
 
Update:
So I was FINALLY able to get back out to the garage today and I removed e starter and was unable to turn it by hand. However..... I put a socket on the nut with a bar and indeed it does turn. It's just quite tight. I'm thinking that's very good thing !! I tried it in forward and in neutral. The prop turns when I turn the flywheel in forward and doesn't move when it's in neutral as expected.

Now my question is, why is it so stiff ? I'm guessing the next thing I want to do is take the leg off ?
Any thoughts on what it might be ? I have hope that there is hope !
 
Well, it may not be such a good thing at all. My first suspicion about how an engine got that tight would be that it was overheated to the point that the pistons and cylinders deformed.

Although, it could also be because a lack of lubrication could have caused the crankshaft bearings to begin to seize on the journals.

Another thing that can occur when it starves for oil is that the oil pump could seize. This would be a very repairable situation if nothing else was damaged. The pump is bolted to the cylinder head and driven by the camshaft. It pulls oil up from the sump through a screen type filter on the end of the pickup tube. That screen can get clogged with sludge because it is inaccessible for cleaning unless you take the power head out of the oil case.

Or, it may have ingested liquid into the cylinders or jumped time and caused one or more valves to be bent.

Yes, you can remove the extension case and see if it frees up. You need to remove it anyway if you're going to work on the power head.

I'm sorry to be the bearer of bad news but, at this point, it doesn't sound good to me. I hope you can prove me wrong.
 
Me again.
You can remove the timing belt and see if the camshaft and pump is bound up. And you can try turning the crankshaft to see if the binding is in the lower end. If you find that the valve train or oil pump is the cause then that will likely be an easier, less costly repair.

Good luck.
 
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