Force 50, a question I havent seen answered

1990 Force 50 508F90D

I have seen a lot of questions regarding over heating of outboards, now I have question that I have never seen before. In aquiring a 1990 Force 50 motor that had been over heated, I removed the cyl head. there was a plastic fitting right in front of the thermostat housing that went to a rubber hose, that went up to a water pressure gauge, this had melted, and part of the hose that was close to the head melted also, and the thermostat had melted the wax plug that actuates it. but I noticed on the left side of the thermostat, in the water jacket that surrounds the upper cylinder wall, there is a little rubber seal? that extends parallel to the cylinder axis from the head gasket, to the bottom of the water jacket. this looks as if it effectively forms a dam so that the water has to travel all the way to the bottom of the water jacket channel, and back to the top before it can go out the discharge galley. this little rubber seal, about as big around as a pencil and 3" long fit into a little u channel that was molded into the aluminum? block/water galley. this rubber piece had melted and deformed. Now I have not been able to find this rubber part in any of the pics or diagrams I have looked at, the model no is Force 508F90D. I suppose that this is a very important part, and probably partly why so many people have cooling problems with these outboards.

So my question is, do I really need it, and where can I get it? if it cannot be found could I use a little piece of heater hose and cram it in there to do the job?

thank you in advance for your time

Re: Force 50, a question I havent seen answered

Look at the picture below of a 4 cylinder block. Is this what you are talking about (circled in yellow)? If so....

Yes that rubber piece is important. It is used on many other models, 3, 4 and 5 cylinder motors to divert the water down and around all the cylinders. The parts listings and diagrams do not show it. I use some automotive vacuum line as a replacement when necessary. Don't remember the exact diameter off hand but you can take a piece of it to someplace like NAPA and try and match it up. Doesn't have to be exactly the same just as long as it stays in place and seals good enough to divert the water. Cut it off so that about 1/32nd of an inch is sticking up above the block. This way it will get a good seal against the head gasket when you bolt the head on.

Re: Force 50, a question I havent seen answered

Yes, that is probably what it looked like before it melted, and that is great to know that a piece of heater or vacuum hose will work. I didn't know if it go too hot for standard hose material. I guess if the T-stat opens at 130 degrees, that means that the cyl wall shouldn't be allowed to get much hotter than that, maybe 150?

Yours is in a different place, and that reminds me to check to see if there is/should be one between the cyl walls in a 2 cyl.

I wonder how many people that have heating problems with these engines are missing that piece? in which case the water would just circulate out without properly cooling the cyl walls.

I have purchased a 12v buzzer with a light that I will mount in the dash beside the water pressure gauge that should warn me if the temp switch gets too hot. - the old one did not function when connected to 12V, probably would have saved the problem if the buzzer would have been working.

one more question, what is the chance that I need a new temperature switch (the one in the head) if the head got hot enough to smoke?

Re: Force 50, a question I havent seen answered

njsmail said:

Yes, that is probably what it looked like before it melted, and that is great to know that a piece of heater or vacuum hose will work. I didn't know if it go too hot for standard hose material. I guess if the T-stat opens at 130 degrees, that means that the cyl wall shouldn't be allowed to get much hotter than that, maybe 150?
The vacuum line has worked well so far. Not sure how hot the cylinder walls are, but as long as there is an adequate supply of water flowing through the water jacket, it should be OK

Yours is in a different place, and that reminds me to check to see if there is/should be one between the cyl walls in a 2 cyl.
You can tell by the casting in the cylinder walls in the water jacket. You see the two lips that hold the rubber piece in place.

I wonder how many people that have heating problems with these engines are missing that piece? in which case the water would just circulate out without properly cooling the cyl walls.
Not sure what would happen if the piece was missing. One thing for sure, you wouldn't get very even cooling of the cylinders.

I have purchased a 12v buzzer with a light that I will mount in the dash beside the water pressure gauge that should warn me if the temp switch gets too hot. - the old one did not function when connected to 12V, probably would have saved the problem if the buzzer would have been working.
Yes a buzzer would have saved the day.

one more question, what is the chance that I need a new temperature switch (the one in the head) if the head got hot enough to smoke?

Click to expand...

It's hard to say. You may be able to test it by heating it up with a blow drier and testing for continuity with an OHM meter. The switch is available for $30 - $40. I've seen some heads for various motors on E-Bay with the switch for around $20.