OMC 120hp - Left water intake cap off on lake and overheated bad

vanvalis

Cadet
Joined
Feb 4, 2012
Messages
22
Hello.

I have a 1972 Bell Boy with a 120 hp sterndrive omc. It has the water intake that you hook up the hose to for on land starting. It has a cap. Well I forgot to screw it back on before I headed out on the lake. Ran fine at first for about 5 minutes. Then massive overheat and loud engine operation. I shut it down and could figure out what was wrong. Had to get it started to get back to the dock. Loud engine and lots of exhaust coming out.

My questions about where to start troubleshooting.

Here is my plan.

1. Check the oil
2. Check the compression

What else to determine if I destroyed this thing?

Thanks,

Van
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Re: OMC 120hp - Left water intake cap off on lake and overheated bad

You probably burnt up the hose that connects to your riser.
 

vanvalis

Cadet
Joined
Feb 4, 2012
Messages
22
Re: OMC 120hp - Left water intake cap off on lake and overheated bad

You probably burnt up the hose that connects to your riser.
You totaly nailed it! I went out and checked and that is just what happened! Spot on. Thanks man!

I will replace that thing, check the compression and hope to get back out on the water.

Take care.

Van
 

Redrig

Master Chief Petty Officer
Joined
Oct 13, 2009
Messages
849
Re: OMC 120hp - Left water intake cap off on lake and overheated bad

I am suprised this happened, isnt that pivot point below the waterline ? I wonder if it was fine while the boat was stationary, but once you took off, it came out of the water.

I would think that if you left that off, the impeller would just suck water through that cap rather than the pick up tube.

either way, I hope you didnt do major damage. Good luck
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Re: OMC 120hp - Left water intake cap off on lake and overheated bad

That fitting that is covered by the cap is after the impeller. All the water that the impeller was pumping was going out that fitting.

I know that sounds counter intuitive but when you flush using that fitting, the water you are supplying goes to the engine but also is actually pushed down to the output of the impeller. Even though it is going to the output to the impeller, it keeps the impeller lubricated enough so it doesn't burn up.
 
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