What thermostat

[skeffer]

I have a 1978 470 mercruiser and was wondering what temp the t-stat should be. I don't have my book yet to look it up.

 

[Wart T]

Re: What thermostat

140

 

[crazy charlie]

Re: What thermostat

OBFG,140 degrees is for a raw water cooled engine.If I am correct the 470 is fresh water cooled and that would make the thermostat 170.With that particular motor I would get the manual as fast as possible.Many things different than other marine engines.Charlie

 

[Wart T]

Re: What thermostat

170 works for me too.

 

[skeffer]

Re: What thermostat

It came in the mail but what is the differents between raw water colled and fresh water cooled. Mine has the coolant system and makes use of a heat exchanger where it brings in water for the stern pump if I understand it correctly. I am having a overheat problem at wot but at idle it seems to be okay. Was wondering about t stat and how much water flow should be at heat exchanger from stern pump. I changed out the impeller and it was worn thought maybe piece may be in exchanger. not sure how big the lines in the exchanger are and am I looking down the correct path.

 

[skeffer]

Re: What thermostat

It came in the mail but what is the differents between raw water colled and fresh water cooled. Mine has the coolant system and makes use of a heat exchanger where it brings in water for the stern pump if I understand it correctly. I am having a overheat problem at wot but at idle it seems to be okay. Was wondering about t stat and how much water flow should be at heat exchanger from stern pump. I changed out the impeller and it was worn thought maybe piece may be in exchanger. not sure how big the lines in the exchanger are and am I looking down the correct path.

 

[crazy charlie]

Re: What thermostat

If you have a heat exchanger ,then you are fresh water cooled like a car.Some boats without a heat exchanger take lake or bay water and run it through the block and manifolds.You should probably give your heat exchanger a good cleaning too..How old are the manifolds and risers.There are update kits for that engine that have larger manifolds and risers.Charlie

 

[skeffer]

Re: What thermostat

How old are the manifolds and risers<br />I do not know Tho I have only one exh man and where is the riser as I can not find it in the book

 

[rodbolt]

Re: What thermostat

if thisd rig is new to you then replace the riser and the seawater pump. the riser was a choke point and if water cannot exit it cannot keep the heat exchanger cool.<br /> I have a brand new riser for the cast iron manifold that was ran for 15 minutes. if ya need something like that let me know.<br /> good luck and keep posting.<br /> ps I think the operating range of that engine is 170 to 205 or there abouts.

 

[crazy charlie]

Re: What thermostat

The riser is bolted to the top side of the manifold.Charlie

 

[skeffer]

Re: What thermostat

This must be what the manual is calling the exhaust elbow. Rodbolt the pump (impeller has been changed) about a week ago. The manual shows a elbow and a reservoir on top of the manifold. the cold water from the heat exchanger goes to the elbow.

 

[skeffer]

Re: What thermostat

Is there a way to tell if the riser is bad. I hate to take it all apart and replace it for no reason. where it is is not exactly a easy place to get to.