Logo
FULL SITE MENU

mercruiser 228 cooling query

J

jackman

Contributing Member
Boat has been out of the for last 18 months and soon due to go back in the water. On occasion I've run the engine using ears(rectangular shape which covers all the inlet holes) connected to the stern drive with good water pressure. A small amount of the water escapes where the ears latch onto the stern drive but I assume this is normal. Correct me if I'm wrong. Anyway the engine starts immediately runs at 900rpm but after 10 minutes the temperature guage needle suddenly rises from normal towards red and the rocker covers become too hot to put a hand on so I immediately switch off and the needle drops back. Would this normally be the case when using ears or perhaps the impeller may need replacing. Thanks for any info.
 
jackman said:
Boat has been out of the for last 18 months and soon due to go back in the water. On occasion I've run the engine using ears(rectangular shape which covers all the inlet holes) connected to the stern drive with good water pressure. A small amount of the water escapes where the ears latch onto the stern drive but I assume this is normal. Correct me if I'm wrong. Anyway the engine starts immediately runs at 900rpm but after 10 minutes the temperature guage needle suddenly rises from normal towards red and the rocker covers become too hot to put a hand on so I immediately switch off and the needle drops back. Would this normally be the case when using ears or perhaps the impeller may need replacing. Thanks for any info.
Click to expand...

Nope,... Not normal,... replace the impeller...
 
18 months with the impeller sitting at rest within the pump body is not good.

Merc uses an eccentrically positioned impeller (in lieu of a cam used in many other sea water pumps).

Whether eccentrically positoned, or a cam style sea water pump, three or four impeller vanes are folded against the eccentric area or cam area.
This causes the impeller material to take a "set".
Seldom will an impeller recover from this, and in particular 18 months of it.


Ditto..... change the impeller, and examine the pump body.


Furthermore..... and just an FYI..... winter lay-up is NOT the time to install a new impeller.
Hold off on this until re-commissioning in the Spring time.


.
 
Last edited:
Back
Top