ThePinkPanther
21-09-2011, 01:20 PM
OK, briefly I have an OMC Cobra 5.8 L stern drive (Volvo leg) that was recently overhauled with a new bellows and standard maintenance completed.
On the trip home from the Marina, it's temperature shot up from the usual 160/170 to well over 200 degrees C.
Over the following days, I replaced the thermostat, put in a new impeller and checked/replaced a couple of hoses but all to no avail.
One crazy aspect is that when I trim UP the leg, the temperature INCREASES immediately by about 20 - 30 degrees, trim DOWN and temp drops to normal.
If I trim UP to the point of cavitation, the temp will climb by 30-40 degrees.
Now, here is the kicker!
When I throttle back to idle, the temp will DROP back to normal in less than FIVE SECONDS!
This seems weird to me as I would have thought it would have stayed hot for quite a while and dropped back slowly. The needle virtually falls straight back as you watch ..........
The gauge has never played up before and I doubt it is suddenly malfunctioning.
So, what cooling pipes live inside the leg that could have been pinched or cut during servicing? I am assuming that UP/DOWN moment of the leg is somehow reducing the salt water intake flow - somehow?
Got me beaten this one!
Any ideas appreciated.
On the trip home from the Marina, it's temperature shot up from the usual 160/170 to well over 200 degrees C.
Over the following days, I replaced the thermostat, put in a new impeller and checked/replaced a couple of hoses but all to no avail.
One crazy aspect is that when I trim UP the leg, the temperature INCREASES immediately by about 20 - 30 degrees, trim DOWN and temp drops to normal.
If I trim UP to the point of cavitation, the temp will climb by 30-40 degrees.
Now, here is the kicker!
When I throttle back to idle, the temp will DROP back to normal in less than FIVE SECONDS!
This seems weird to me as I would have thought it would have stayed hot for quite a while and dropped back slowly. The needle virtually falls straight back as you watch ..........
The gauge has never played up before and I doubt it is suddenly malfunctioning.
So, what cooling pipes live inside the leg that could have been pinched or cut during servicing? I am assuming that UP/DOWN moment of the leg is somehow reducing the salt water intake flow - somehow?
Got me beaten this one!
Any ideas appreciated.