How hot is too hot ?

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 !

Have you ever noticed it before?

The reason I ask is that my 88 Mariner 50 was doing the same thing yesterday. Normally I wouldn’t have noticed, but I was out innertubing with the kids and when I was on the tube pulling myself toward the boat I noticed a similar thing.

My personal belief (prayer) is that the weather was just that darned nice. The low humidity meant that it didn’t take much to generate steam… there was even steam rolling off my arms after I got out of the water. Mine has a warning bell that sounds when the engine overheats, so I assume everything was both hunky and dory.

No, I never noticed it. When I put the muffs on it to winterize it, it never used to get that hot, but that was running in the driveway. I’m wondering if my inpeller(s) are just getting worn down on the water pump or something ?

At least you can be reasonably sure it is getting water. Have you ever had the water pump impeller replaced? I have a new one put in my motor about every 3 years. do you start the motor out of the water? I read somewhere that running my motor out of the water (dry) for anything over 45 seconds would pretty much destroy the impeller! A question back at you? Would a leaky head gasket cause the water to get hotter? Does the tell tale stream spit air in the stream or is it continuous? Hopefully it is not serious. At least consider replacing the impeller during the winterizing process if it has not been done for some time.

Check your impeller, with that kind of delay it probably needs replacing.

I had a ding-a-ling moment on a ramp in N WI.

The ramp was very bad and sloped to one side. I was having a hard tiime getting it on straight. I was trying to take out at a very busy time. I would crank it up, pull it out and it was crooked. I would pull it back out, wait for a couple of boats to get going and try again. 3rd time I drove it on and forgot I had the motor running. I pulled it out of the water, looked at it, remembered the motor was running and immediately truned it off. It was out of the water no more than 30 seconds. I’m wondering now if I did damage since reading this thread. It’s an ’01 Merc. 90 ELPTO. What are the chances that it damaged? I haven’t run it since.

TBW,

WOW, you asked this question about 2 mins before me. I have a 1995 Merc 40 hp 4cyld. 2 cycle. The water takes about 20 seconds to come out and the water is hot. I can touch it but man it is hot, can see steam as well.

I have only had the boat for about 1 month so it came this way. My next move was to check and replace the impeller. Perhaps this is just how it is?

Moss Boss said his dad has a similar motor and has the same reaction.

Now on my evinrude 60hp it takes about 2 seconds for the water to appear and is about the temp of the river?

I guess this may not be apples to apples?

WEIRD? Perhaps not?

If you do find anything out will you let me know.

Thanks

I may be wrong ,but I think Mariner is made by Mercury . If its like my two Mercurys they have a thermostat in them to work that way . I still would check it out with a mechanic .

Quote:

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I pulled it out of the water, looked at it, remembered the motor was running and immediately truned it off. It was out of the water no more than 30 seconds. I’m wondering now if I did damage since reading this thread. It’s an ’01 Merc. 90 ELPTO. What are the chances that it damaged? I haven’t run it since.

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I think you are probably OK. There was hopefully enough water in the lower unit to lubricate the impeller for the 30 seconds. If it were bone dry, I would be a bit worried.

Since it is an 2001 motor, it likely is at or near to 100 hour mark and time for a impeller and water pump change. The kit is less that $60 and it’s and easier job than disc brakes on a car! If you need help, let me know.

Jon J.

Jon,

Whew!

After I got the boat to the tie-down area I lowered the motor. There seemed to be plenty of water running out.

I don’t get out as much as I would like with my travel schedule. I bought the boat in the Spring of ’02. It was a carry over from the previous year. It’s really only had a year and a half of very average use. I’ll probably have the dealership I bought it from do the kit for me when I put it away for the winter. I really appreciate the advice and knowledge you bring to the board.

Thank You!

SteveO

TBW,
Have you noticed one other thing about the motor is it a gas HOG? Mine seems to be. I thought the 4 cylinder would be EZ on the fule but that does not seem to be the case. Just a side note question.

You most likely need a new impeller in the water pump. They will wear, and like a prior post said, you should replace them about every 3 years. Only one way to verify before purchase. Check a maintenance book on your motor and find out how much water press that that motor is supposed to have at idle, and at lets say 2000rpm. (The book should tell you what rpm to measure at.)You also could try to pry the info from a dealer/service outfit. If it is lower than spec., then you need a new impeller. You need to do this on the water, and not your driveway. The water pressure in your hose will overtake what the impeller will do. That’s probably why you didn’t notice it last fall when you put it away. The rubber impeller is a cheap part, (normally less than $20.), and with “middle of the road” mechanic skills, this is a easy part to replace. Good luck!