over-heating issues

[chalvata]

I just purchased my first boat and need some help. Mercruiser 470 engine. Over heats after about half an hour at high rpm. Did all the common things.... new thermostat, flushed system, removed and cleaned heat exchanger, new raw water pump, inspected engine water pump and installed repair sleeve and new seal, replaced a couple of bad hoses. Cleaned alot of crud out of lower half of out drive when installing raw water pump, now when test running it water comes out of hole in bottom of outdrive. Is this normal? Hole was plugged with crud. It appears normal to me being that theres a hole in the raw pump housing that puts water into lower unit. I am unexperienced when it comes to boats. Any help would be highly appreciated. Don't know if it still overheats as I just finished the work today. Going to lake Thursday. Also the speedometer dont work....any suggestions what to look for there? Thanks!!

 

[Bondo]

Re: over-heating issues

Ayuh,... What Vintage is it,..?? Does it have the 3" heat exchanger,..??

 

[chalvata]

Re: over-heating issues

It is a 1979 Steury deep v open bow 18'. With the 3" heat exchanger. Do you know if the water out of the hole on bottom of outdrive is normal? When i bought this boat the previous owner had the heat exchanger out of it and had it set up for raw water cooling by connecting the raw water hoses to the fresh water hoses. Is this a wise idea to cure an over heating problem? he said it was becuase the heat exchanger leaked, but new end seals fixed that. Thanks

 

[sdoomaha]

Re: over-heating issues

Yes that is normal. No it is not a good wise cure....it was set up with the heat exchanger for a reason.

Good Luck....hope your overheat is cured.

 

[chalvata]

Re: over-heating issues

thanks for the info on the water. I figured bypassing the heat exchanger wasnt a good idea, thats why i put it back in when i got it. will know soon if problem is fixed or not.

 

[chalvata]

Re: over-heating issues

Well nothing to update on overheating issues....I ended up having to work Thursday so didnt make it to the lake. Should be going tomorrow(Sunday).... will post what it does after i get back. If anyone knows where i may be able to get a 4" heat exchanger for this boat please let me know. Thanks.

 

[Bondo]

Re: over-heating issues

If anyone knows where i may be able to get a 4" heat exchanger for this boat please let me know.

Ayuh,... ebay or craigslist,...
There are No New parts available for those motors... Used is your Only option...

 

[b_ry]

Re: over-heating issues

he is right check ebay, a couple of weeks the had a 4" conversion kit from 3"to4". it was new and it would fit a 79 470 like mine and yours. the only problem was that the kit was 5 bills. but maybe a used one would work fine. good luck. and water doesnt come out that hole in the bottom of the outdrive on mine. if it still overheats check those elbows damn things plug up with rust. good luck