How hot is too hot ?

TBW

Recruit
Joined
Jul 12, 2003
Messages
2
I think I might be having a problem with my motor and perhaps there's a knowledgable mech in the crowd that can give me some ideas or help. <br />I have a 1993 Mariner 40 H.P., 4 cyl., 2 stroke Magnum motor on my fishing boat and while I was on the river today, I noticed that it seemed to be running hot. By hot I mean the water coming out of the engine was actually steaming ! It was too hot to touch. I was trolling for 20 minutes before I noticed it. I took it out and ran it wide open for 5 minutes thinking it might cool off, by it really didn't get much cooler. It was still steaming. Also, it seems to take 15 or 20 seconds before the stream starts after I start the motor. I took the hose off where it connects to the motor, and I can blow easily thru the intake below, so It's not an obstruction. <br />Is this normal ? I've never paid too much attention to it, but don't recall it ever steaming like that. <br /><br />What should I do or look for ? I was gonna check the hose inside and pull the guards off the intake to have a look. <br /><br />Any ideas ? <br /><br />Thanks folks !
 

paulgp6022

Petty Officer 1st Class
Joined
Jul 27, 2002
Messages
288
Re: How hot is too hot ?

If you have a thermostat, it could be sticking. If not ,you could have an obstruction of sorts.
 

roscoe

Supreme Mariner
Joined
Oct 30, 2002
Messages
21,819
Re: How hot is too hot ?

This is typical of a bad impeller, that is about to fail.<br /><br />Replace the impeller, or entire water pump, NOW. Don't wait till it fails or it could cost you your entire engine. Also replace thermostat.<br /><br />Telltale should show water stream within 2-3 seconds, and water should should start out cool, then increase to about 140 degrees maximum.<br /><br />The job is easy to do with a manual and a little time.
 

millerpdt

Seaman Apprentice
Joined
Apr 13, 2002
Messages
46
Re: How hot is too hot ?

roscoe is correct! do the impeller and the thermostat. if one needs replacing do them both!! the stream should never be so hot that you cannot hold your hand under it for extended time. if it is there is trouble.
 

TBW

Recruit
Joined
Jul 12, 2003
Messages
2
Re: How hot is too hot ?

Thanks guys !<br /><br />I don't think it's an obstruction, because I can blow air easily through the engine (if I remove the tube from where the water comes out of the exterior)but the worn impeller sounds logical. Anyone have a clue what the damages typically are for a impeller/thermostat combo or a water pump ?
 
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