siezed up seahorse 18hp

ok so i have a 1959 johnston seahorse 18 hp i went to roll over and the pistons are seized up and a head bolt is broke im just wondering is it worth taking somewhere to get fixed there is some rust on the bottom cynlider

Re: siezed up seahorse 18hp

Is this a motor you have been using regularly or has it been sitting for many years? The approach is different.

Re: siezed up seahorse 18hp

It has set for like 5 to 6 yrs

Re: siezed up seahorse 18hp

Hi 00tjwrangler. Well, if you're a tinkerer at heart and aren't trying to get your money back out of the motor, then I'd say it's worth the effort. The '50s era 18 hp are some of the most desirable vintage motors to have, especially if they have the two-tone paint job. Parts are still available, and the motors themselves are very simple to rebuild. All that being said, you could probably find the same, or similar motor that is not seized, or is in running condition for about the cost of what it would take to bring the dead one back to life.

Re: siezed up seahorse 18hp

If you choose to resurrect it, start by pulling the plugs and spraying your choice of penetrating oil into the cylinders and let them soak for a good long while to loosen up the rings. Then gently try turning the flywheel while adding penetrating oil, eventually it should loosen up.

Re: siezed up seahorse 18hp

Ok thank u I've looked around a little and haven't found anything near my price range and Idk how much would cost to have someone rebuild it

Re: siezed up seahorse 18hp

Won't the head leak where the bolt broke off after it starts?

Re: siezed up seahorse 18hp

You can rebuild the whole thing yourself. There really aren't any special tools required. In fact, there have been several top to bottom vintage 18 hp rebuilds here in the forums lately. +1 on rockyrude's suggestion about trying to loosen up the current pistons. Deep Creep, Sea foam and/or Automatic Transmission Fluid mixed with Acetone all make good penetrating oils. It may take several day, but with some luck you can get the motor to turn over enough to check the compression. If the compression is ok, then the rest is easy. If the compression is not so great then you might have more to deal with. It may only need a head gasket ($20 + elbow grease), but if that doesn't do it you'll probably have to open up the power head to check things out.

It may not necessarily leak. Head bolts can/do break pretty often. You certainly don't want to leave it that way, but it should hold long enough for you to get an approximate compression reading.....hopefully.

Re: siezed up seahorse 18hp

To have some one else do all the work, way more than replacing the motor. The only way to do it on the cheap is to do it yourself if you can. The broken bolt will also need to be fixed.

Re: siezed up seahorse 18hp

ok well i have never rebuilt a motor but i do like to tinker so im going to try so maybe how much would this run me

Re: siezed up seahorse 18hp

Start by trying to get the motor to rotate. If you can't get that, the rest doesn't matter.

Re: siezed up seahorse 18hp

A normal top to bottom tune up for one of these guys is about $150, which includes a new carb kit, lower unit reseal kit, and ignition rebuild (w/new coils) and more. If your motor does not already have a fuel pump and you want to add on so you can run a modern, single line fuel pump set up, which most folks tend to do, that will be another $50-$60, less if you don't mind it looking less than stock, but that's an optional modification. As far as the internals of the engine go, that will depend on what it needs. You can get replacement cylinders and rings for about $100-$120 from places like ebay, but if you check vintage OMC enthusiast sites like aomci.org, one of the folks there may be able to hook you up rings, pistons and a fuel pump for quite a bit less. As far as paint jobs and cosmetics, that depends. If you want a showroom restoration, you'll probably need to have all of the components soda blasted down to raw metal (it's like sand blasting, but less harsh to the aluminum parts). It's probably about $100 to have everything taken down to bare metal, but it will save you TONS of work and give you a perfect finish surface to start with. Nymarine.com has factory correct colors and decals for you motor, but they ain't cheap. However, you can get colors that are very similar to stock from most autoparts stores for much less.
If you can get the motor to turn over and the internals are ok, it should only cost about $150-$200 to get her running again, including a decent paint job, but if you want to go all out and make it better than show room, you're looking at more like $400-$500, but it'll be the best lookin', best running motor on the water and will literally out live you. Hope that helps. Keep us posted. We love pics

Re: siezed up seahorse 18hp

It the bottom cylinder is rusted, the bearing, crank, rods, etc... are rusted as well. The powerhead will need to be opened up so might as well do it now, it will aid in getting the piston moving again.

Re: siezed up seahorse 18hp

At the very least, you've got a good parts motor for another Johnnyrude 18 or 20 of the 1950s & 1960s era. Great motors and worth salvaging to some degree. There are lots of them out there - you may find another one with a busted lower unit for cheap. Combine, and voila! Cheap runner! Gotta take the motor apart in either case, whether you save it or use it for parts...