Hello!
I am repairing my boat after it overheated, and have it to the point that the engine runs at normal temperature when running under 3000 RPM, but it heated back up to 225+ after 2 minutes when run at higher RPM.
This was my first maintenance outing after the first set of repairs, so I only did this once before coming back in. The engine cooled quickly when running at low speed.
Disclaimer: I'm new to boats, but now have enough knowledge to fully understand how silly I was to get myself into this position in the first place. Thanks for any replies!
Engine is a 1985 Mercruiser 120hp 2.5L.
History-
-Boat overheated and broke a belt.
-Overheat was caused by old impellar and water pump, belt broke becasue the water recirculating pump was corroded and dragging.
-Overheat destroyed said water pump and impellar, and the flapper in the exhaust elbow. The rubber exhaust bellows was also cooked enough to create a slow water leak.
-When working on engine, found timing gear cover corroded through, and t-stat housing fairly corroded as well.
Work performed
-Replaced water recirculating pump, belt, and timing gear cover.
-Cleaned corrosion off of t-stat housing.
-Replaced Water Pump and Impellar. (This was professionally done, as I was unable to separate the upper and lower gear house covers in the sterndrive due to corrosion.)
-changed the oil/filter
Work still to be done
-Replace the exhaust bellows.
-Replace the flapper in water exhaust elbow.
I am waiting for parts to arrive to complete the work to be done, but I am concerned that I still have an undiagnosed overheating problem after yesterday's maintenance run.
I've read posts that indicate cracked header or blown head gasket that only presents at higher RPMs, or the possibility that the water pump was not correctly sealed when replaced.
Can the small leak in the water rubber exhaust bellows cause an overheat at higher RPM? the lack of pressure, maybe?
The water exits through the propeller, there could be debris inside of the lower gear case, but I'd expect a water flow issue to present an overheat at any running speed, not just higher RPMs... right?
Thanks for any help!
-
I am repairing my boat after it overheated, and have it to the point that the engine runs at normal temperature when running under 3000 RPM, but it heated back up to 225+ after 2 minutes when run at higher RPM.
This was my first maintenance outing after the first set of repairs, so I only did this once before coming back in. The engine cooled quickly when running at low speed.
Disclaimer: I'm new to boats, but now have enough knowledge to fully understand how silly I was to get myself into this position in the first place. Thanks for any replies!
Engine is a 1985 Mercruiser 120hp 2.5L.
History-
-Boat overheated and broke a belt.
-Overheat was caused by old impellar and water pump, belt broke becasue the water recirculating pump was corroded and dragging.
-Overheat destroyed said water pump and impellar, and the flapper in the exhaust elbow. The rubber exhaust bellows was also cooked enough to create a slow water leak.
-When working on engine, found timing gear cover corroded through, and t-stat housing fairly corroded as well.
Work performed
-Replaced water recirculating pump, belt, and timing gear cover.
-Cleaned corrosion off of t-stat housing.
-Replaced Water Pump and Impellar. (This was professionally done, as I was unable to separate the upper and lower gear house covers in the sterndrive due to corrosion.)
-changed the oil/filter
Work still to be done
-Replace the exhaust bellows.
-Replace the flapper in water exhaust elbow.
I am waiting for parts to arrive to complete the work to be done, but I am concerned that I still have an undiagnosed overheating problem after yesterday's maintenance run.
I've read posts that indicate cracked header or blown head gasket that only presents at higher RPMs, or the possibility that the water pump was not correctly sealed when replaced.
Can the small leak in the water rubber exhaust bellows cause an overheat at higher RPM? the lack of pressure, maybe?
The water exits through the propeller, there could be debris inside of the lower gear case, but I'd expect a water flow issue to present an overheat at any running speed, not just higher RPMs... right?
Thanks for any help!
-