Volvo overheating

[davewild]

I have a volvo 2002(model number not year). For the last 6 months or there-abouts it has been having over heating problems. Originaly had a blockage in intake - now fixed. It runs for maybe 15 minutes before alarm sounds. Impeller, thermostat, filter, intake and hoses all seam to be ok.
Engine is sea water cooled. Water comes in through stop valve to a heat exchanger to cool engine oil then to filter and into motor. When running I do get water coming out of exhaust. Any ideas would be welcome. I have always sailed with out an engine but this boat is a little to big and pen is difficult to enter with prevailing breeze. Thanks, Dave.

[Paul_L]

There is a fluid drain plug on the starboard side of the engine closer to the rear lower part of the block. Try opening this and seeing if water flows out properly. You can stick something into this hole to break up possible junk that is just near the outlet. If not, you may need to flush the system. Check the exhaust elbow. They crud-up and degrade after 20 years. Check the thermostat and make sure it is opening at close to the right temp for a raw water cooled engined.

Paul L

[davewild]

Thanks Paul,

I will have a look at drain hole and exhaust elbow next time I'm down at the boat. I did pull out the thermostat and it was working but looked old. While it was out I replaced it and housing as well. Do you think that it could be the sender giving a false signal? If so how would you check this?

Thanks for taking The time for your reply. I would call a mechanic but money is tight in the current economic climate and I really would like to become able to fix the motor myself( with a little help via forums such as this).

Thanks again,

Dave

[Paul_L]

You can purchase a cheap non-contact thermometer for $30-40. These are really handy for looking at the temps in different parts of the engine.

Paul L