Logo
FULL SITE MENU

My 1986 470 is also overheating

P

pop pop

New member
I have a 1986 470 that is over heating at wot but not at idle . I changed the impeller checked the exchanger for blockage none found; checked thermastat it was bad so I removed it . Still overheats checked compression it is good.Pulled exhaust elbow it is rusty in side. also the flapper is totaly gone ; could this be my problem? HELP!!!!!
 
Re: My 470 is also overheating

pop pop said:
I have a 1986 470 that is over heating at wot but not at idle . I changed the impeller checked the exchanger for blockage none found; checked thermastat it was bad so I removed it . Still overheats checked compression it is good.Pulled exhaust elbow it is rusty in side. also the flapper is totaly gone ; could this be my problem? HELP!!!!!
Click to expand...

I would replace the exhaust elbow ..I had to do this ..the rust blocks flow/exhaust then leaks..

I drain this out after I run the engine so it keeps the elbow from rusting faster ..
 
Re: My 470 is also overheating

speaking of 470.....is there somewhere I can go to find out the step by step instructions on replacing the impeller? Also, the engine is a 470...but the sterndrive also has 470 on it....how do I know what the sterndrive model is? or is it 470 as well?

My 470 overheated....I'm guessing impeller first..anything else I should change at the same time?
 
Re: My 470 is also overheating

Well, for anyone that was reading...had the impeller changed. Maximum temperature is 160 and holds steady.

The impeller that came out only had one fin left intact.
 
Re: My 470 is also overheating

pop pop said:
I have a 1986 470 that is over heating at wot but not at idle . I changed the impeller checked the exchanger for blockage none found; checked thermastat it was bad so I removed it . Still overheats checked compression it is good.Pulled exhaust elbow it is rusty in side. also the flapper is totaly gone ; could this be my problem? HELP!!!!!
Click to expand...

sorry I didn't see you removed the thermostat to see if it will run cooler...that is a NO NO >>>the thermostat must be installed to properly route the coolant through the heat exchanger properly , to regulate the temp..removing this thermostat will cause overheating as well as a defective one ..you must use the OEM spec thermostat it must be the same design !
 
Re: My 470 is also overheating

Did you ever look for the flapper, if it;s not there in it's spot then it fell down and is blocking the exhaust.

And the pieces of the impeller where are they, usually they are in the hose that enter the transom or the t-stat housing and yes the exchanger.
 
Re: My 470 is also overheating

hello anyone that can help please- I am a first time boat owner and i bought a 1987 470 merc with an alpha one sterndrive. since the first time i had it in the water this year(my first time behind the wheel) I have been having an over heating problem. with a 160deg thermostat, she will run fine for awhile and then start to steam around the engine and blow coolant out the overflow tube into the bilge. then i took the thermostat out and went to the lake and tried that, it was a bigger mistake, the temp shot to 280 and stayed there, I shut her off and got an embarressing tow back to the dock, but i didnt blow her up at least. My oil is nice and clean, and my pressure is good. Can anyone help me without going to an expensive dealer, that i cant afford to do??? thank you very much.....cal
 
Re: My 470 is also overheating

extra to my 470 problem- I have also tried a 180deg thermostat with the samed results. thanks.....cal ps- where are the bellows???
 
Re: My 470 is also overheating

papabear.....

put the 160 tstat back in.....check your impeller in your out drive....and you may have to change the exhaust elbow...other than while apart check voltage reg. power steering cooler and bellows for flapper it may be broken and causing flow problems....but I would, elbow you can find for about 200$ IMPELLER kit about 30$ the rest you can clean yourself.....and one more thing check that your heat exchager is clear.....
 
Back
Top