Logo
FULL SITE MENU

Volvo Penta 3.0 overheating!!

M

MNHOG

New member
The impeller went last fall and it overheated (smoke) before shutting down. I've replaced the impeller, thermostat, water pump and exhaust/water connection off the manifold. Also found the backwash flapper stuck down in the out tube and removed that. It's moving some water at low speed/rpm. But overheats when I open it up. What next???
 
Check for corrosion/leaks @ the water elbow, i.e., the point at which the water line to the drive attaches to the drive ( and the gasket)... a leak (air) at this point will cause overheating ... could also cause water pump failure if bad enough... air in the water line instead of water.
 
sandkicker said:
Check for corrosion/leaks @ the water elbow, i.e., the point at which the water line to the drive attaches to the drive ( and the gasket)... a leak (air) at this point will cause overheating ... could also cause water pump failure if bad enough... air in the water line instead of water.
Click to expand...

Thanks. I'll check that. I also found the raw water tests in the repair manual. For flow and air intake.
. I'll try that first.
 
OK. Did the air test with the clear hose. No air at at least 12" of water stream off the impeller outlet. Boat ran very well at low speed at for 10 mins at high speed. Saw the gage drop just over 180, so the thermostat was working. Then we saw another black chunk pass through the clear hose. About nickel size. Then the temp started to rise at leveled off about 220. So I took the thermostat housing apart thinking the chunk was lodged in the thermostat. But no sign of it. It passed through at least there. My question is, when I was a kid we ran without a thermostat sometimes. Seemed to work fine. Could I do that with this motor?
 
Well, if the piece isn't stuck in the t'stat you need to find it. I'd look to see if it was blocking the flow of water out the exhaust elbow. re: "seemed to work fine".... yep on any given day no t'stat is better than a stuck one, however, removing the tstat will result in the engine notoperating at it's design temperature. Most noticeable result will be a loss in fuel economy.... ugly things eventually happen to the engine oil as well.
 
sandkicker said:
Well, if the piece isn't stuck in the t'stat you need to find it. I'd look to see if it was blocking the flow of water out the exhaust elbow. re: "seemed to work fine".... yep on any given day no t'stat is better than a stuck one, however, removing the tstat will result in the engine notoperating at it's design temperature. Most noticeable result will be a loss in fuel economy.... ugly things eventually happen to the engine oil as well.
Click to expand...

Couldn't find any piece of impeller. I have good flow through all hoses and through the exhaust manifold and elbow. Put in a new thermostat and put it back together. As usual, it runs fine in the driveway using the muffs. I'll need to get it on the water for another real test one night this week. Grandkids want to go tubing for the fourth. If its still overheating, I'm about done. I won't know what else to do except take it someone. I hate that.
 
Back
Top