1969 55hp flyweel very hot after 20 minutes

I have done lot of thing on this motor to be able to start it and have it running:

Redo some old wiring, change the waterpump, adjust points, clean the advance timing handle and lube it, it move well now when the engine is cold.

Now I am still stuck with this problem, after 20 minutes on the lake the flyweel become very hot and then the timing advance handle under it became very difficult to move and the motor stop to work until it cools down. The case of the motor is not hot only the flyweel area.

I have even remove the thermostat same result after 20 minute flyweel too hot I will not burn my hand on it but I feel it is very hot.

With the ears on I could see water pouring of the propeller when the engine running, also I have remove the thermostat cover and start the engine lot of water pouring from the thermostat ole.

Engine is working very fine when cold ... I can't figure out why is the advance handle area become so hot and stiff to a point that the timing handle is not following the trottle and the engine dies. The rest of the engine is not hot, only warm.

By the way I am still searching the site ...

Any ideas, Thanks

Re: 1969 55hp flyweel very hot after 20 minutes

I am only guessing here but you might pull the flywheel and visually inspect what is rubbing up there if your engine case is cool. My '83 had the same problem but I had a blockage in a water jacket that cleared it up.

Re: 1969 55hp flyweel very hot after 20 minutes

fireman57 said:

I am only guessing here but you might pull the flywheel and visually inspect what is rubbing up there if your engine case is cool. My '83 had the same problem but I had a blockage in a water jacket that cleared it up.

Click to expand...

Thanks Fireman, I have removed the flyweel and nothing seems to rub everything is clean under the flyweel, I am wondering how much hot is too hot on the flyweel, after a ride of 20 minute the flyweel is very hot but I could put my hand on it without burning my fingers maybe it is normal and my overheating diagnostic is not good?


Something that I am sure of is that after 20 minute the timer base is sticking and is not folowing the trottle, but it is free when the flyweel get cold again?

I have read on this board that some guys are prying the little L braquet that hold timer base so that it is more loose, I will try that too this weekend, maybe with the heat the metal is expanding and the timer base braket are too tight and it is jamming?

Weird problem ...:'(

Re: 1969 55hp flyweel very hot after 20 minutes

Check the thread a little below you that says Aramature Plate? (25hp) and see if it helps.

Re: 1969 55hp flyweel very hot after 20 minutes

I had a similar problem with a '70 3 cyl 75 hp. It would start and run great then after about 20 min it would run rough and finally the engine froze at WOT.

In short the thermostat was going bad and finally did freeze shut. I know you removed your stat but that is what caused my problem.

Water is supposed to come out the hub when on muffs and engine running.

Are you in salt water?

When is the last time you changed your impeller in your water pump?

The reason why the linkage binds when hot is the dimensions changed, because of the heat, and it is jamming.

HTH

Mark

Re: 1969 55hp flyweel very hot after 20 minutes

I still think that you have an overheat problem as Texasmark says. Remove your lower unit and your thermostat cover and use a 1/2" garden hose clamped to your water pipe from your lower unit and turn on the water. Let the pressure flush your system and you might be surprised to see what comes out. Make sure you remove the tstat so you get a good flow. If you can find a 3/8" nipple then you can flush the head too by inserting it in the water jacket after where the tstat goes..

Re: 1969 55hp flyweel very hot after 20 minutes


All good information thanks, I think I need to work a little more on the overheating problem ...

To answer your question, it is used in fresh water only, I have changed the complete water pump a week ago I was lucky to find and OMC complete kit, and I have done the flushing thing on the tubes from the base unit when I have replaced the pump, but at that time my thermostat was still installed.

I will flush also the powerhead as you suggested Fireman57, could not hurt and maybe I have a blocage in the top end of the engine and it is why removing the thermostat did not fix it ?

Maybe I will figure out when I will be infront of the engine but if you could be more precise about where to put the 3/8 nipple to flush from top, is it in inside the engine where the thermostat goes ?

Re: 1969 55hp flyweel very hot after 20 minutes

Yes, when you remove the tstat you will see where the water would flow once it opens. You can then insert the nipple in there to flush the rest of the powerhead. Make sure that when you run it you have a known good tstat in there as it provides the proper pressure to assure that all the water passages are filled. If you run without it your pee stream will be weaker, your passages might not be filled all the way, you will be running a "cold" engine all the time, and you could have a cylinder that is hotter or cooler than the other one and it will definitely lead to a problem you don't want.

Re: 1969 55hp flyweel very hot after 20 minutes

If it continues, bite the bullet and pull off your water jacket cover, over the head, and have a look. With that off, you can do the hose thing and insure that the lower end is working. If you are careful and don't break off any screws, all you're out is a gasket and some time; but who knows you might find your problem.


It's pretty straight forward; the pump sucks up water, pushes it into and through the block and out the exhaust manifold and downand around the exhaust tube. Anything that prevents this from happening is suspect.

Then once you have done that, eliminated cooling as the source, you may have a different kind of problem like running too lean or improper load (lugging).

Mark

Re: 1969 55hp flyweel very hot after 20 minutes

Thanks for the help, here is the resolution of this problem, if it could help somebody else, I am happy to share with you.

I have verified the motor this weekend and flush again the powerhead with water from the top, and I have verify the water path it seems to be clear, no restriction.

However I have found my problem, during my testing I realised that my timer base was starting to stick a bit even when only warm and getting worst when at normal working temperature.

I remove the flyweel and the time base and I realised that the distributor cap was causing the problem, I can't figure out why but it is rubbing on the timer base , anyway, I was luky that I was still having an old distribution cap to test and with the other one the timer base is easier to move it is completely free even when the engine is hot.

Got this old engine to the lake for an hour and it is running perfectly now.

Thanks again,

Re: 1969 55hp flyweel very hot after 20 minutes

I hope that you found this from when I ask you to check the thread of armature base. I just assumed that you had. Anyhoo, I'm glad that you found the problem and got it resolved. Even happier that you posted the solution as a lot of people don't. i hope that you get to enjoy the rest of the season trouble free.

Re: 1969 55hp flyweel very hot after 20 minutes

Me too on both counts. Wish more folks were that thoughtful/thankful. Besides making you day, it gives you confidence that you know what you are talking about when you try helping out. 8)

Mark

Re: 1969 55hp flyweel very hot after 20 minutes

Fireman57,

Yes I have checked the tread on the armature base, while it was not exactly the same symptoms, I was curious and it gives me another good reason to remove the flyweel and check everything again, and that is how I have discovered that the cap distributor was the problem ...

I am impressed by the dedication and experience of the members of this board.

8)8)8)8)

Re: 1969 55hp flyweel very hot after 20 minutes

I know it wasn't exactly the same symptoms but if your timer base was sticking or loose it could have caused the problem. Thanks for hanging with us. Make sure you stick around and post for others.