over heating 470

[fishanator]

I am at wicks end with this motor!!! I tried everything- the heat exchanger, manifold and thermostat. I had the water pump on the out drive changed this past winter. Water flows through every hose I take off. Over heats when moving and idle. Cools down when I bring it up in rpm's not in gear. Checked plugs and oil, no water or signs of water. Seems to be a slight knock in front end of motor. Could this be a timing matter. This is a 1981, and it's in a 20' grady white w/a. Please any input will help. thank-you.

 

[Don S]

Re: over heating 470

Could this be a timing matter.

Check it and find out!

Have you checked the exhaust riser to see if it's pluged up?

 

[fishanator]

Re: over heating 470

Yes, took it off yesterday and no blockage.

 

[fishanator]

Re: over heating 470

bump to the top

 

[bomar76]

Re: over heating 470

Could this be a timing matter. QUOTE]


Could be, ever give any thought to checking the timing?????????????

 

[fishanator]

Re: over heating 470

Yes, I have to find someone with a timing light. How does the timing effect the temp?

 

[bomar76]

Re: over heating 470

With retarded timing, the exhaust valve opens while the flame is still burning. The piston, on it's upstroke, pushes these burning gasses out the exhaust valve into the head. This tremedous extra heat in the head ovewhelms the cooling capablity of the engine, and thus it overheats.

Retarded timing will also result in a low power output as the expanding burning gasses are chasing the piston down, instead of pushing it.

 

[fishanator]

Re: over heating 470

thank you for your replies. It cools down when I rev it out of gear?

 

[Mobiletek]

Re: over heating 470

I would check your impeller again. If it is not cooling at idle it might be missing a fin and not constructing enough pressure for your HEX. I assume you have a 3" HEX? Maybe your water intake grates are clogged/corroded just enough that they don't get enough flow under low pressure. Have you found anything parts or pieces in the sides of the HEX?