2.5 litre Mercruiser 120 not pulling water through pump or prop spinning

[Thunder-pat]

I have an 84 thundercraft with a 2.5 liter mercruiser 120 engine. It is not pulling water through the newly changed impeller and housing. The prop seems to not spin when engine on and throttle engaged. Took of the hoses and no water coming up. Is it possible the drive shaft is not turning? Or is the lower or upper unit the problem since the prop isn't spinning. Lower unit splines looked good. Please help, my wife is already not happy that I bought the boat!!! Lol!!!

 

[GA_Boater]

Welcome aboard.

Lets back up a bit. You just bought the boat, so how was it during the lake test? Did it cool OK before changing the water pump parts?

Run the motor but for a few seconds until the water issue is repaired or more things will end up burning up. The Admiral will be even more upset.

 

[Thunder-pat]

I bought the boat without a water test. Rolled the dice. He said the impeller needed to be changed and that it was not a good idea to start up without it. Since it was a good deal, I went forward. I put the muffs on when I started it up and no water came out the exhaust. So shut it down. Also noticed the prop was not spinning at all

 

[GA_Boater]

The coupler may be shot. Do you smell any burnt rubber sniffing around the back of the motor?

 

[Thunder-pat]

I was thinking that could be a possibility. No I didn't smell anything burned. Although I didn't let it run long when I started it. Is there a test i can do to figure it out?

 

[Old Ironmaker]

The money you saved by buying a 40 year old boat without a test in the water might be best going towards a divorce lawyer. Man I hate being the bearer of bad news but I don't even know where to start. I've been accused of being a pessimist but I would say more of a realist. At least we know the engine runs. There is a lag period before the thermostat opens on most outboards. The time depends on how cold the water is running from the hose. Sometimes the overflow can get plugged, run a stiff piece of weed wacker line down the tube then start it up again. Let it run for 45 seconds, it will seem like hours. If nothing coming out of the discharge port shut her off. Lets start there and let us know.

 

[Chris1956]

Gee, take the prop off. Put the motor in gear with ign off. Turn prop nut tight and continue to turn, and see if engine turns.

If engine doesn't turn then outdrive or coupler are suspect. Pull outdrive and inspect splines on upper gearcase, U joints etc.

See if coupler looks bad.