84 OMC overheating still

J

jjbass24

Cadet
Joined
May 5, 2013
Messages
8
Just replaced the impellar and thermostat on my 84 OMC sterndrive not a fun job pulling the outdrive and the shift cables I must say! After working on it all day and putting all new fluids in it fired it up and the temp gauge goes to 240 degrees almost immediatly. I can grab the inlet and outlet hose on either side of the thermostat and hold onto them they do not feel that hot also have pressure on both hoses. Could it be a bad sending unit to the gauge or a bad gauge? It is a GM 2.5 liter
 
S

stang32

Chief Petty Officer
Joined
Jul 16, 2004
Messages
513
Re: 84 OMC overheating still

what does the exhaust riser feel like? is it untouchable? if so your engine is overheating.
check the thermostat, if it has not been changed in a while, change it. actually, first pull it, run the engine w/ no therm. it should run very cool. then work on other areas, if the gauge goes to hot right away, within minutes of start up, check the sending unit.
these usually dont go bad but its worth looking @.
 
J

jjbass24

Cadet
Joined
May 5, 2013
Messages
8
Re: 84 OMC overheating still

stang32 said:
what does the exhaust riser feel like? is it untouchable? if so your engine is overheating.
check the thermostat, if it has not been changed in a while, change it. actually, first pull it, run the engine w/ no therm. it should run very cool. then work on other areas, if the gauge goes to hot right away, within minutes of start up, check the sending unit.
these usually dont go bad but its worth looking @.
Click to expand...

I put a new 160degree thermostat in while I tore it apart for the impellor not knowing how old it was. I did not think to run it without the thermostat just got really frustrated after putting all the hours into it for the impellor. Thanks I will try pulling the thermostat and running without it and will also check how hot the exhaust riser gets before i do that.
 
Howard Sterndrive

Howard Sterndrive

Rear Admiral
Joined
Nov 5, 2008
Messages
4,603
Re: 84 OMC overheating still

is the overheating on muffs or in the lake?

first step would be to pull the hose at the thermostat housing and start the engine and see what comes out - water should shoot out almost a foot at idle
 
J

jjbass24

Cadet
Joined
May 5, 2013
Messages
8
Re: 84 OMC overheating still

over heating on the muffs. Can I check the line like you are saying on the muffs or should I have it in the water. This is my first I/O and trying to learn, its not like my old outboard I could drop in a bucket and run
 
Howard Sterndrive

Howard Sterndrive

Rear Admiral
Joined
Nov 5, 2008
Messages
4,603
Re: 84 OMC overheating still

do you have the garden hose on full blast? you should
does water pour through the prop (steady stream) and the anode grate at the bottom of the intermediate before you start it? it should be pouring out those 2 places pretty heavy
 
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