Rising temp

[CARMINE326]

I have a 302 Volvo Penta with a external raw water pump and a sx outdrive. Just put a new Volvo Penta thermastat in it with a new impeller in the pump and a new temp switch. When I am above 3800 rmp the temp will increase until I lower the rpm to under 3600. I have new risers and wonder if the lower unit is sucking air or I have a bad thermastat. Need help on this matter please.

 

[Walt T]

Re: Rising temp

The typical place for a Volvo to draw air is at the nipple on the drive where the hose connects to it. As a general rule overheating at idle is an impeller problem, overheating at speed is a restriction problem, or in your case, drawing in air. The nipple and hose are submerged below planing and raise up out of the water at speed. Worth checking first.

 

[CARMINE326]

Re: Rising temp

Thank you for the insight. I have removed the lower unit and replaced the 2 o-rings that are on the nipple. It might be that the seal between the lower unit and the transom unit is not right. I did buy new seals and pipe that goes between the upper and lower unit but have not installed them yet. Could this be a cause for air?

 

[vinney]

Re: Rising temp

Sx drive right. If the belt driven water pump has been over heated (run dry) copper a blue color. There is an internal seal(behind the impeller in the pump) that will suck air and over heat on the higher rpms. The seal is not shown on the newer sx drives. If you go back to older models of sx drives you will find that seal. If you dont want to replace the seal you can replace the pump as an assemble. The new pump is larger than the first pumps put on sx drives. Install a new impeller if you replace the seal.

 

[CARMINE326]

Re: Rising temp

It is a 95 sx-c 1:66 ratio drive. I would have never thought to look there. Thank you for you help.