Help with cooling (Gamefisher, Force, Mercury, 15 hp outboard)

Mattawoman301

Recruit
Joined
May 27, 2016
Messages
2
I am new to the forum. Been, lurking whenever in need info, but never posted.

My motor recently failed me on the river after a long day (about 10 miles) where it had been performing flawlessly. After some research I came to the conclusion that I thought I had a blown head gasket. So, I purchased a gasket and proceeded to change it. While I had the head off I cleaned everything up as nicely as I could and re-assembled.

It started right up, but I noticed right away that it wasn't pumping water. Probably what blew the head gasket in the first place. So, I shut it down and removed the lower to check the water pump. As it turns out the impeller was badly worn and melted. I could find no clogs or obstructions, so I don't know how this could happen. There was obviously some heat/friction involved. Anyway, I cleaned up the waterpump housing and installed a new impeller.

After re-installing the lower and testing... It started out with a pretty decent stream, so i decided to let it idle for a while and I noticed that as it went on the stream got smaller and eventually stopped. I pulled the lower off again and it seemed to be fine, so I re-assembled after lubricating with some 2 cycle oil and the stream was noticeably increased.

In general, after multiple reps at troubleshooting and testing I have noticed that the motor just seems to run well, but way too hot even when water is pumping (I think, although I have nothing to compare it too). Please take a look at the video below to try and show what I mean. From a cold start the head will sizzle water like grease in a frying pan after a minute or so.

https://www.youtube.com/watch?v=adjcH47o3w8

The only things that I know of (from the manual) that are not in proper order on this motor are that the thermostat is missing and the water jacket tube (deflector) is missing. From my research I don't think these things could cause my problems. I have a new water jacket tube, but have been hesitant to install it because I would have to remove the head again and install a new gasket.

But, I am an armature does anyone here have any advice or a similar experience with the cooling system? Can I re-use the head gasket if it is not damaged?

Thanks for any input!
 

Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,817
From the video, you may have a solid stream of cooling water but that is way too weak to indicate a good cooling is in place. Since the old impeller was tattered into pieces it would not be surprising that parts of it may have blocked water passages, thermostat or even partially the water tube. You will need to do a thorough inspection and even doing some blowbacks to clear the debris. And as for the head gasket, yes if it is not damaged you can reuse it. It is not recommended by others but I've done it before and it works perfectly. Make sure you follow the correct torque pattern for the head and at least a two step torquing procedure.
 
Last edited:

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,923
Welcome.
​Always include the year or serial #
Looks like it's a late 90's model.

The sizzle is NOT good.
When you removed the head was there any crud build up in the cooling passages??
The old impeller and pump housing, and what was in the thermos housing, post a video of that.
After 5 posts you can add pics to your posts.

Jiggz mentioned the pipe or pickup tube could be clogged with old impeller pieces??

Most of the exhaust exits from the snout on the bottom.

Without the thermo it should be really whizzing out the port.
You should replace it.
 

tommarvin

Ensign
Joined
Nov 22, 2015
Messages
999
If the old impeller didn't come out in one piece, the fins and pieces are blocking the water cooling passages.
Drop the lower unit, check the impeller, if this is your first impeller change,watch you-tube videos until you feel comfortable.
Push a wire up the water intake tube to clear any blockages, put t the hose where the stat was flush to clear any blockages, is water flowing out the intake copper tube.
What going on is pieces of your impeller are moving around your motor blocking the cooling passages.
If you can take a head gasket off check the cooling passages again you should check it.
I don't know what the water jacket tube is, I would install a new tube and stat so the motor will idle better at start up, after you fix this
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,923
Tom, did you read what he posted?
​Did you read what Jiggz posted?
Did you read anything anyone posted?

IF?? the pieces are moving around they probably would have gone through the system
IF??? they were still in there they would block the passages causing an overheat.

Mattawoman(as in creek??) forgot this on my other post. You can reuse the gasket if it hasn't melted the sealing rubber too much.
I use black sillycone to seal a gasket that's not working good.
 

Mattawoman301

Recruit
Joined
May 27, 2016
Messages
2
Thanks for the replies guys.

With the lower off, I have applied water pressure forward (waterline to pee hole) and backward (pee hole to waterline). I do not believe there is any loose pieces of debris.

There was a bit of crud built up in the water jacket, but I cleaned that up pretty good when I had the head off. I don't think the water line / pipe is obstructed, but I suppose it could have a lot of build-up.

I replaced the impeller (will post a pic soon), I didn't replace the pump housing, just spent some time cleaning it up. I never found any debris anything in the thermostat housing.

Yes, I have spent most of my fishing time on Mattawoman Creek since I was a little boy.
 
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