How hot is too hot ?

[Guest]

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.
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.

Is this normal ? I've never paid too much attention to it, but don't recall it ever steaming like that.

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.

Any ideas ?

Thanks folks !

[pengy]

Sounds like a water pump problem to me. I was told they should be changed on a regular basis (every 3-5 years depending upon many things) to be on the safe side.

[musky hunter]

It's too hot! I just had the same problem with my 120 Force. This engine has a thermostat, and it stuck shut. It got so hot that the motor quit in the middle of a run and scored one of the cylinders. I am facing a rebuild because of it. If it's the water pump, you will have a test plug on the top of the motor. You should get a good stream out of it. You may not have a thermostat at all, but something else to check.

[ScoutII]

I was told Mariners run too warm with a thermostat. I was told to take the thermostat out and leave it out. Had to put in a water pump impeler, top side was chewed up pretty bad. Seems to be doing fine now. Good luck.

[huskminn]

This is all I know about Mariners....my dad has one and after he started it once on a cool day, I notice there was no water coming out of it. Of course, I found this quite concerning, but he laughed and said it has a thermostat and it's not warm enough to run water through yet.

So, the 15-20 seconds of no water is at times common, I think, but it does sound like your thermostat isn't functioning properly. No way should you be able to make a cup of tea from your cooling water stream.

[fishingdad]

I had a 28hp mariner that the same thing happened to me and after I replaced the impeller it was night and day difference or hot and cold in this case.I would definently replace the impeller and I'm sure your problem will be resolved Good Luck

[Chris Haley]

It needs a new impeller for sure, maybe even a pump. You shouldn't be able to make tea with your cooling system. A 40 hp shouldn't have a thermo so you should have water right from the start.

[Guest]

Update !

Had the shop put in a new impeller. I gguess the old one was toast. I haven't had it on the water yet but hopefully we got the problem taken care of.

Thanks for all your relpies !

Happy fishin' !