Help!! OMC 350 overheating -UPDATED-

[Chevy13s]

I just put a new crate motor in my 78 sunrunner. I started it for the first time yesterday and everything worked great and the temp stayed right at 160 the whole time.

Today I fired it up again and it started to get hot so i shut it down. I disconnected the hose from the outdrive and with the garden hose turned on nothing came out. I can blow through the hose with no resistance even with the garden hose turned on. Please help, I was hoping to put it in the water this weekend but Im fearing a water pump. Do water pumps go bad just like that? Good one day not the other? Shouldnt the garden hose push through the pump to the motor even if it is bad?

It is an omc 800 outdrive and I was using muffs.

Thanks,

Ken

 

[KaGee]

Re: Help!! OMC 350 overheating

Re: Help!! OMC 350 overheating

Maybe the water pressure in the hose was too low? That, or you may have a bad impeller in the drive water pump. Does your drive have the pee hole near the ball bear on the intermediate housing? I always look for the stream there as a sign my impeller is OK.

Another check is to pull the inlet hose off of the thermostat housing and inspect the water stream there.

 

[Chevy13s]

Re: Help!! OMC 350 overheating

Re: Help!! OMC 350 overheating

that is the hose i pulled off and no water was coming out of it.

 

[KaGee]

Re: Help!! OMC 350 overheating

Re: Help!! OMC 350 overheating

that is the hose i pulled off and no water was coming out of it.

Your troubles are in the drive.
Will the drive go in gear and spin the propeller?

 

[Chevy13s]

Re: Help!! OMC 350 overheating

Re: Help!! OMC 350 overheating

yes it does

 

[95yj]

Re: Help!! OMC 350 overheating

Re: Help!! OMC 350 overheating

How long was it sitting? The impeller can get brittle sitting especially if the drive is in the sun. It's pretty common to start up a boat that's sat and have it cool OK and then later during the same outing or the next time it's started have it overheat due to the impeller coming apart during the first outing.

If you don't know when the impeller was last changed or if the boat has sat for a while or run at all without a water source, change the impeller. This is normal maintenance and the last thing you want to do is gernade a new motor for $150 worth of parts.

I've noticed that water doesn't normally blow through the impeller when it isn't turning, so putting the hose on when the motor is off probably won't show water flowing. Once you start the motor, that's when you'll see the flow. Also hose pressure can mask an impeller that isn't pumping up to snuff. (The boat cools fine on the hose but slowly overheats on the lake.)

 

[KaGee]

Re: Help!! OMC 350 overheating

Re: Help!! OMC 350 overheating

that is the hose i pulled off and no water was coming out of it.

Was the engine running when you pulled the hose? If so, you will probably find that the water pump impeller is shot. If the engine was not running, you need to repeat the test with it running.

The drive going into gear is a good thing, it means the splines on the waterpump drive shaft are OK.

Personally, having gone to the time and trouble to load a crate motor up into your project, I would have put a waterpump kit in it from the get go.

 

[Chevy13s]

Re: Help!! OMC 350 overheating

Re: Help!! OMC 350 overheating

yes it was running while i pulled the hose. This is my first boat. I got a Selec repair manual for the stern drive but it didnt say how often to change the impeller. It just told me to do this big long test of filling buckets out of the hoses. If it was good it was good in the book. The boat was sitting for at least a year until I got my hands on it about a month ago.

Does it matter if the drive is up or down on the 800? I noticed the exhaust is not connected to the prop anymore as soon as I trim up a little. Just wondering if the water line would do something like that?

 

[lilsinker]

Re: Help!! OMC 350 overheating

Re: Help!! OMC 350 overheating

The water will still flow when the outdrive is tilted up, but you will quickly destroy the ball gears if you run it with the outdrive up. Also try looking at the muffs when you are trying to run it. See if a substantial amount of water is leaking out around the cups. If so, get new muffs.

 

[Chevy13s]

Re: Help!! OMC 350 overheating

Re: Help!! OMC 350 overheating

Ok so I pulled the water pump out and it looks great like it was replaced soon before the boat sat. A little dryrot if you bend it but it should have been working(before you say anything a new one is going in anyway).

So now I dont know what to do. I guess a seal blew out somewhere? When I had it hooked up to water I had it trimmed up a little bit for ground clearance issues and the water was all coming out somewhere around the exhaust on the PROP side, maybe a little higher. It was hard to tell. I was thinking maybe the water pump gasket would let it leak right into the exhaust chamber?

Any Ideas?

Thanks guys.

 

[MikDee]

Re: Help!! OMC 350 overheating -UPDATED-

Are you sure your garden hose was flowing water? I had a dollar store nozzle one time, that shut itself off when you put it on full, and I was unaware of it, and thought my impeller was bad too.

 

[wire2]

Re: Help!! OMC 350 overheating -UPDATED-

There will be water running out of the mid drive if you have it tilted up even slightly, as the exhaust passage is not coupled any more. If tilt is down and you have it trimmed up you should still see water running out of several places but not as much.
I'd try pulling a trunnion cap off 1 side, put the muffs on, turn tap on & start it. Water flowing from cap spot?

If yes;
from there it goes through mid drive, then a hose to power steering heat exchanger, another hose to thermostat housing. Open those connections 1 at a time to see where the flow ceases.
If no;
problem is between water intake and trunnion cap

 

[Chevy13s]

Re: Help!! OMC 350 overheating -UPDATED-

Ok so I just replaced the waterpump. Still Nothing! I pulled off a trunion cap and with the hose on, engine running, nothing came out. However, there WAS water coming out of the weep hole by the balll gears if that helps. The boat goes in and out of gear fine. Any Ideas? Im really frustrated.

Thanks, Ken