502 Overheating
 

I have a 1999 271 with a 502 MPI. Lately after putting the boat in the water I get a high temperature after about a minute or two. If I take the outlet hose off of the seawater pump and restart the motor it will pump water. I then put the hose back on and it will then pump water through the motor and the temp is normal. If I leave the boat in the water at the dock, it will start and run fine. Anybody got any ideas as to what is causing this to happen? Thanks for any input.:confused:

formulafastech,
After I put the outlet hose back on (after starting the motor with it off for a few seconds) the temp. comes right back down to normal. After that the boat runs fine for the rest of the time out that day.

Did you replace the T-stat recently? If so make sure it has a hole in it. If not drill about a 1/8" hole in it. If you do not have that you will see this problem as water is not flowing throught the entire block as you warm up. Is water coming out the exhaust as you are running it at first?

Jon

Audiofn,
I didn't change the thermostat. I only see a very small amount of water coming out of the exhaust at first then nothing. Like I said, I pull the water pump outlet hose off, start the motor and water will pump, put the hose back on and temperature comes right back down to normal.:confused:

Have you run aground recently maybe causeing you to suck up sand? If so then I would check the oil coolers and so on. I would also just in case take a look at your raw water pump. When is the last time you changed it?

Jon

271, just my .02 but could it be a bad impeller(sp) I have seen this once before,

Good luck

Do you have a sea strainer?

masi242,

I checked the impeller and it's like new, it was a new one last year. I took the boat out yesterday and it started and ran fine with no temperature problems at all. I also took most of the hoses off and flushed water through them.:confused:

cuda,
No I don't have a sea strainer, would one help with sucking up sand?

Do you have a freshwater flush system on it. If so check the unit out it could be stuck. It has a checkvalve type mechanism.