New boat (for me) with a engine question OMC 120hp

[alkialki]

Hey, I picked up a 1974 Fiberform Bowrider a while ago and have a question about this motor that I can find in either of the manuals I have. Its a OMC 120hp 1974. I have the OG one, but its very general. I have had the engine running and it runs good just need to know some things.

1. On the port side of the engine there was a plug sitting on the floor. Im talking block plug here. I found the spot where is goes, Im just wondering why its out. I was thinking maybe the previous owner was using this place to stick a hose while running the engine, but its not the type of plug to be removed easily. I want to just put it in, but I would like someone to ease my mind before I hammer it back because I dont think its going to come out again. (It looks to me like it needs to stay in.)


You can see in these pics the engine, boat, and this plug and location that I am talking about.

Thanks for any help. Im ready to get this thing on the watwer already!!!

 

[bomar76]

Re: New boat (for me) with a engine question OMC 120hp

That's a casting core plug from the manufacturing process. They are often incorrectly called freeze plugs.
They sometimes will pop out when the water in the engine freezes due to lack of winterization.
You say you had it running....did you have water going through engine?
If not, you have FUBARED a number of things.
If so, water would have been POURING out of the missing core plug.

Please tell us.

 

[alkialki]

Re: New boat (for me) with a engine question OMC 120hp

I ran it out of the water to make sure it runs when I bought it. Less than a minute so it didnt overheat.

I later dropped it into the lake and ran it. I only had it in the water for a half hour or so, but I was running it and I didnt sink.

I thought that was what it was. I guess I am good to go hammer this back in???

I gotta say thats the ugliest mug Ive ever seen.

 

[bomar76]

Re: New boat (for me) with a engine question OMC 120hp

If that plug was missing when it had water running though the engine it would sink the boat in minutes.

And NEVER NEVER NEVER NEVER run a boat without it hooked up to water for ever a second. EVER.
The first thing to fry is the impeller that pumps cooling water to the engine - in seconds-, then water goes to exhaust manifold, and exhaust hoses. The hoses will burn up long before engine overheats dry.

 

[bomar76]

Re: New boat (for me) with a engine question OMC 120hp

I gotta say thats the ugliest mug Ive ever seen.

I was thinking the same thing about that boat!

 

[alkialki]

Re: New boat (for me) with a engine question OMC 120hp

If that plug was missing when it had water running though the engine it would sink the boat in minutes.

And NEVER NEVER NEVER NEVER run a boat without it hooked up to water for ever a second. EVER.
The first thing to fry is the impeller that pumps cooling water to the engine - in seconds-, then water goes to exhaust manifold, and exhaust hoses. The hoses will burn up long before engine overheats dry.

It definately had water running through and like I said I didnt sink. I do have good luck sometimes though

Yes I suppose thats a bad idea, but had to make sure it runs before I go to the trouble of towing it to my shop.

I saw the inlet thats behind the prop, but is there a better place to stick a hose if I ever have to run this again out of the water?

Thanks for your help btw. Ugly mug and all.

 

[bomar76]

Re: New boat (for me) with a engine question OMC 120hp

If it just fell out on it's own it would have had to have been on the trailer ride from the lake.
I would be seriously concerned about the condition of the other core plugs. As I said, if one falls out the boat will fill with water in no time at all.

Do not hammer that old junk one back in, go buy a new set of BRASS core plugs and replace all of them. Clean holes up well , use a socket of appropriate size, I personally use LOCTITE'S 's core plug sealant or LOCTITE 30512 Gasket Sealant #1 , goop them up and drive in.

 

[T-Bone Coug]

Re: New boat (for me) with a engine question OMC 120hp

Don will chime in soon with the graphic showing how fast the impeller gets toasted. Don't even bother starting it again until you've replaced it.

 

[alkialki]

Re: New boat (for me) with a engine question OMC 120hp

So anyone know how I can I run this with a hose or anything? I had trouble with the gear shifting mechanism (as In I got it in the water and it wouldnt stay in drive so I couldnt go anywhere)

But Im pretty sure I fixed the problem with a simple cable adjustment, but want to run it to make sure. I dont want to get stuck in the middle of the lake.

Any advice? I have 2 manuals and neither say anything about this.

 

[T-Bone Coug]

Re: New boat (for me) with a engine question OMC 120hp

Did you ever replace the impeller? If not the chances of you getting stuck in the middle go up exponentially. Someone else will have to inform you about hooking the hose up, but like I said: Your impeller's toast.

 

[alkialki]

Re: New boat (for me) with a engine question OMC 120hp

No not yet. I am going to take the sterndrive apart to get a look at it today.

At least thats the plan.

 

[T-Bone Coug]

Re: New boat (for me) with a engine question OMC 120hp

Just as an FYI, here is a link to a description of what happens to an impeller when it is run dry. It is a merc manual, but is also pretty much universal when it come to the damage. Keep in mind, the impeller should be soft and flexible, with the vanes straight. No curves. If there are curves then it has cooked. See page 2.

http://www.boatfix.com/merc/Bullet/87/87_14.pdf

Like I said, once you've done that, I'm not certain how a hose hooks up to your drive. Mine is an Alpha1 and uses standard muffs over the water intake ports on the drive.

Good luck!

 

[alkialki]

Re: New boat (for me) with a engine question OMC 120hp

Took it apart and the vanes are definitely curved. Ordering a new one now. Unless I can find a place local in Seattle to get one from.


So anyone know where I can hook up a hose to this engine to run out of water? I would really like to do this as I can really work on my boat at a public boat launch.

 

[madurodave]

Re: New boat (for me) with a engine question OMC 120hp

buy some muffs, screw on water hose, put on outdrive, turn on water

 

[boat127]

Re: New boat (for me) with a engine question OMC 120hp

to bomar

man thats the sweetest mug i ever seen

 

[Howard Sterndrive]

Re: New boat (for me) with a engine question OMC 120hp

buy some muffs, screw on water hose, put on outdrive, turn on water

not on the type of drive being discussed here

 

[alkialki]

Re: New boat (for me) with a engine question OMC 120hp

Just as an FYI, here is a link to a description of what happens to an impeller when it is run dry. It is a merc manual, but is also pretty much universal when it come to the damage. Keep in mind, the impeller should be soft and flexible, with the vanes straight. No curves. If there are curves then it has cooked. See page 2.

http://www.boatfix.com/merc/Bullet/87/87_14.pdf

Like I said, once you've done that, I'm not certain how a hose hooks up to your drive. Mine is an Alpha1 and uses standard muffs over the water intake ports on the drive.

Good luck!

Ok so I went ahead and ordered a new one one your advice that the vanes should not be curved, but the vanes dont fit into the pump without them being curved. After taking this apart twice it seems there is no damage to the impeller at all.

 

[alkialki]

Re: New boat (for me) with a engine question OMC 120hp

Soo great. Putting it back together this time I dropped the lower and pulled out the shift cable about 6"

I will see tomorrow if I am f'd.

 

[T-Bone Coug]

Re: New boat (for me) with a engine question OMC 120hp

Soo great. Putting it back together this time I dropped the lower and pulled out the shift cable about 6"

I will see tomorrow if I am f'd.

Hope it works out ok.

FYI- The vanes will always be curved in the housing. It's when they stay curved upon removal, or lose flexibility that you are at risk.

 

[superbenk]

Re: New boat (for me) with a engine question OMC 120hp

Speaking of running the engine out of the water, make sure you have the trunion cap with the garden hose adapter & ALWAYS run a hose to the outdrive BEFORE starting the engine (as said previously). See this thread:

http://forums.iboats.com/showthread.php?t=336474

Also, for the fun of it, I found this on Google Books Funny to see OMC in popular publications from when I was a kid (my boat is so old ):

http://books.google.com/books?id=kY...se flush adapter&pg=PA189#v=onepage&q&f=false