Volvo Penta I/O overheating?

Question

replaced the impeller and checked the thermostat and it is still over heating. Suggestions?

Answer 1

If this is the volvo 4 cyl or 6 cyl in line engine-there were many possibilities.

First- if it only overheats on plane but cools off when idling- you have an air leak at the water manifold right under the u-joint boot.(outside the boat) It is held on with 2 allen head bolts and sealed with a rubber gasket/"o" ring combination. They liked to get salty and swell-bending the casting -then the salt would wash away causing the air leak. You can check this by splicing a piece of clear hose into the water "in" line where it clamps to the incoming side of the pump on the front of the engine.(inside the boat) If it is full of air bubbles then it's leaking

Second- these had a full flow oil cooler near/under the starter. The incoming water flowed round tiny tubes of brass. If you grounded the boat in exactly the right size sand/gravel it would absolutely run hot. This is a bugger to disassemble and clean. It has tiny "o" rings and big skinny ones and you absolutely have to get the seal right between the oil and the water or you will think you have a bad head gasket.

Third- The 6 cyl had a long brass tube flowing coolant from the front of the cylinder head to the back- inside the cyl head water galley-If this got dislodged the back of the six ran rather hot.

If you have a v-8 all bets are off.

  

Answer 2

    More info would be nice! I would never give the mechanics that worked for me a new impeller, unless they could find all the pieces to the old one! They will cause blockage elsewhere unless found. There is a s shaped hose externally from drive to transom plate that could be bad; a lot of reasons. remove the hose after water pump, start and check for pump output. Realisticallylly take to dealer for proper diagnosis!

Answer 3

If you could edit your question and tell us which volvo engine you have would help!  It can be loose belts on circulation pump, or a bad pump.  It could also be cooling system issues.  I'd remove the thermostat and rum for a period with it out.  That tells you a lot.  Don't let it overheat but up to 200 is ok!