motor getting very hot very fast

jayrider · Apr 12, 2010

i have a 1973 switzercraft with a mercury 120 hp i/o i took it out the other day for the first time the temp gauge went to the red within a couple of minutes i felt the hoses and they were hot so i took it back in to shore. ive been racing dirt bikes since i was 10 im 27 now so i know my way around the garage but im not all that experienced with boats. is there any way to tell if its the impeller could it be the outlet for the used water is clogged the motor has water in it but it wasnt flowing in and out as it should any suggestions or ideas would be greatly appreciated

Don S · Apr 12, 2010

Re: motor getting very hot very fast

Did you ever run the engine on land without water going to the outdrive?

crazy charlie · Apr 13, 2010

Re: motor getting very hot very fast

Sounds like no cooling water getting to the motor.Start with a new impeller and a new tstat and go from there.Charlie

jayrider · Apr 13, 2010

Re: motor getting very hot very fast

yes i ran the motor out of water for a minute it fired right up and sounded great so i didnt give it much thought today im gonna mess with it the only thing im having trouble with is why the water wont leave the motor from what i undrestand the water should come out around the exhaust could the outlet be clogged or does the impeller work like a vacume where it has to push fresh water in for it to flow out?

jayrider · Apr 13, 2010

Re: motor getting very hot very fast

the thermostat opened up at about 150 degrees that seems ok i think so is it the impeller then im gonna pull it and look

Lodgepole · Apr 13, 2010

Re: motor getting very hot very fast

Do not run engine with boat out of the water unless you have water connected. You will fry the impeller in no time.

Don S · Apr 13, 2010

Re: motor getting very hot very fast

jayrider · Apr 13, 2010

Re: motor getting very hot very fast

Lodgepole said:
Do not run engine with boat out of the water unless you have water connected. You will fry the impeller in no time.

oh i would never do that

jayrider · Apr 13, 2010

Re: motor getting very hot very fast

Don S said:

yea its the impeller it looks all ate up ill change that and i hope thats it thanks guys

jayrider · Apr 13, 2010

Re: motor getting very hot very fast

i think im going to order the whole kit new pump housing gaskets etc. how would i go about finding out what the numbers are for the one i need?

cr2k · Apr 13, 2010

Re: motor getting very hot very fast

Make sure you have EVERY piece of the old impeller or you will have blockage.
The small pieces will travel thru your cooling system and block flow.

Start at the heat exchanger and pull the hose that comes from the transom and check for any debris. Then the thermostat.

Should be done any time the impeller is found to be ANY amount less then complete.

jayrider · Apr 13, 2010

Re: motor getting very hot very fast

yea i pulled out all the pieces and blew everything out including the hose so i should be good on that

motor getting very hot very fast

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