Motor locked up

oldthang

Cadet
Joined
Apr 22, 2012
Messages
6
I have a 1957 Johson 18 hp seahorse thats be setting for years. I don't know very much about out boards. I have always had i/o's. The motor is locked up tight. I have the head of and wd40 sitting on top of the pistons for the last week . they don't look bad, but still locked. should I be able to turn the motor over with the prop with the head off. Ihave the side cover off also and I can see the pistons through two ports in there. Can any one give me some advice
 

nwcove

Admiral
Joined
May 16, 2011
Messages
6,293
Re: Motor locked up

keep soaking it with penetrating oil, dont try to turn it at the prop, work from the flywheel end. what do the cyl walls look like? does the prop turn freely in neutral ( if it will shift).
 

JDusza

Ensign
Joined
Apr 21, 2009
Messages
934
Re: Motor locked up

Welcome. There is a lot of great advice here.
Yes, You should be able to spin the crank with the head off the engine.
I would avoid trying to turn the crank via the propeller. Can you get the flywheel back on and use it to apply torque?
There are a couple ways to go. You can try to unfreeze the pistons from the outside, not really ever intending to split the engine block or you can sign up for a block tear down.
Although not popular, I have been successful in the past inserting a wooden dowel into the spark plug hole and tapping the piston while applying torque to spin the crank. Not popular, but it has saved me a few tear downs. If you have the head off, you may tap the pistons with a wooden or plastic mallet; tap not bang The pistons rings and / or bearings are frozen. Can you get anything like PB Blaster behind the piston into the crankshaft bearings? Maybe you can snake one of those red spray straws behind the pistons. Do you have the inspection plate and exhaust plate off?
There may be a lot of torque required to break the crank free. I wouldn't recommend trying to get that much from the prop.
J
 

busted-bayliner

Petty Officer 1st Class
Joined
Jun 6, 2010
Messages
228
Re: Motor locked up

i had a bayliner and i thought the motor was locked up turned out to be the lower unit was locked took it off and the motor was free to spin
 

oldthang

Cadet
Joined
Apr 22, 2012
Messages
6
Re: Motor locked up

The cyc. wall look real good I see no damage on them. I have pb blaster sitting on top of the pistons now. I have one cover plate off it's a large one on the tiller side . there are two more small covers on the other side I don't know what they cover. tomorrow I will take them off. I tried taping with a hammer and a block of wood, didn't help. I can see the pistons through the ports behind the large cover plate and they look good also. I really don't want to have to tear this down compleaty if I don't have to I'll keep you posted
 

tx1961whaler

Vice Admiral
Joined
May 31, 2008
Messages
5,197
Re: Motor locked up

Try taking the lower unit off first. It may be that the power head is not locked up at all.......
 
Joined
Dec 3, 2011
Messages
70
Re: Motor locked up

if the lower unit shifts out of gear i wouldnt take it off, just more bolts to loose!!!! if it shifts into neutral i would put the flywheel back on and use that to turn the crank over.
 

lindy46

Captain
Joined
Nov 27, 2008
Messages
3,886
Re: Motor locked up

Try taking the lower unit off first. It may be that the power head is not locked up at all.......

X2 - I've seen a lower unit full of water and bearings totally rusted so nothing would move. At first I thought it was the powerhead, but when I removed the lower unit, the powerhead turned freely.
 

oldthang

Cadet
Joined
Apr 22, 2012
Messages
6
Re: Motor locked up

I am trying to take off the lower unit , it seems to be stuck on the shifting rod. Is the something that has to be disconnected there. If so how do you get to it.
 

oldthang

Cadet
Joined
Apr 22, 2012
Messages
6
Re: Motor locked up

Well I have the lower unit off ,I pulled the power head to disconnect the shifting rod only to learn that on the down tube there is a cover plate to disconnect it there. I guess you learn by doing . the lower unit had to come off any way to change water pump . But It is the power head that is locked up. I have the head and the carb and valve plate off so I can see the connecting rods. I have put plenty of bp blaster (good stuff) In there hopefully in a couple of days things will loosen up.
 

lindy46

Captain
Joined
Nov 27, 2008
Messages
3,886
Re: Motor locked up

PATIENCE! This is not a chat room. If you would have waited a little while, someone would have told you about the shift coupler under the little oval plate on the leg. Would have saved you a lot of time in the long run.
 

oldthang

Cadet
Joined
Apr 22, 2012
Messages
6
Re: Motor locked up

Well I have all the cover plates off and have had PB Blaster sitting on top of the frozen piston which I found when I took off the intake covers . The bottom piston is frozen solid Sounds like hitting an anvil when tapping on it . the top one sounds kinda hollow I have have had BP sitting on top of the piston for over a week now and still frozen . I am ready to bang the **** out of it until something breaks loose. Any body have any suggestions. This motor is really plucking my last nerv
 

nwcove

Admiral
Joined
May 16, 2011
Messages
6,293
Re: Motor locked up

i suggest not banging it too hard, or you will do more damage than you want! how much pressure have you put on the flywheel nut trying to break it free?
 

oldthang

Cadet
Joined
Apr 22, 2012
Messages
6
Re: Motor locked up

enough to bow my bar. I tried striking the bar with a hammer also. I don't know how much more that nut would take.
 

nwcove

Admiral
Joined
May 16, 2011
Messages
6,293
Re: Motor locked up

yikes! it is stuck hard! id try the the acetone and atf, some say its better than anything off the shelf.
 

ultra353

Petty Officer 1st Class
Joined
Jun 21, 2009
Messages
387
Re: Motor locked up

Let the oil do its thing, hopefully it will break free. If it won`t it could be the crank/rod bearing rust and the case will have to be split to really see whats going on.
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: Motor locked up

As suggested, mix ATF and acetone 50/50 and try that. Hope you didn't have the flywheel on when you were cranking on that nut.
 

kodibass

Master Chief Petty Officer
Joined
Apr 10, 2010
Messages
864
Re: Motor locked up

Maybe a small bit of heat from a propane torch, with all the PB blaster she will smoke' so outside operation, heat let cool repeat, soak heat repeat............
 

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
Re: Motor locked up

Pull it apart. If it is stuck that hard, it needs to come ALL the way apart. Open up the crankcase, pull the crankshaft and see what is actually stuck. It will save you much time, frustration and skinned knuckles in the long run to pull it all the way down...
 

BobnTed

Cadet
Joined
Mar 19, 2012
Messages
21
Re: Motor locked up

For what it's worth, a lot of times with old powerheads in that condition the cost of time and parts to repair it warrent a replacement powerhead. One can be purchased from Ebay or put a wanted ad on craigslist.
 
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