Sanibel Life
New Member
I have a 2006 290 SLX with twin 350 mag MPI motors with Bravo 1 drives. I recently developed an overheating issue that I cannot overcome. It began by running well while on plane but would overheat when I returned to idle (manatee zones). I was able to overcome this by backing down slowly on this engine while returning the other to idle. It became worse on the next use and overheats every time the engine is run.
I replaced the impeller in the sea water pump, even though it was perfect on inspection. It was open so why not. I replaced the water circulating pump as well. I back flushed the water distribution hoses to make sure nothing had gotten sucked up in them (impeller pieces, etc) and nothing came out. I felt high temp on the power steering cooler hoses, but when I opened them and flushed/backflushed and the cooler tube water flowed without restriction.
I have replaced the thermostat (twice, just in case). I even removed my thermostat entirely to see if it helped...it didn't. When I disconnect my hoses to the manifold risers (1.7 inch) water flows with what seems like adequate supply. I do notice it is not as much as the normal working engine but it definitely seems to be adequate.
I am able to keep my hands on the risers endlessly though this although my oil filter is very hot. The temp of my exhaust water does not increase (once up to operating temp) even though my temp gauge rises to alarm. I have had my manifolds off within the last 6 months so no rust build up in them. No water in my oil. Fresh oil change.
The only thing that helps is if I open the thermostat housing drain and let water flow into the bilge the temp will come down and run within normal range. I found this by accident but it is not a reasonable thing to flow seawater into your bilge when in the water. Bloop...bloop
I am out of ideas. Any help you can give would be appreciated.
I replaced the impeller in the sea water pump, even though it was perfect on inspection. It was open so why not. I replaced the water circulating pump as well. I back flushed the water distribution hoses to make sure nothing had gotten sucked up in them (impeller pieces, etc) and nothing came out. I felt high temp on the power steering cooler hoses, but when I opened them and flushed/backflushed and the cooler tube water flowed without restriction.
I have replaced the thermostat (twice, just in case). I even removed my thermostat entirely to see if it helped...it didn't. When I disconnect my hoses to the manifold risers (1.7 inch) water flows with what seems like adequate supply. I do notice it is not as much as the normal working engine but it definitely seems to be adequate.
I am able to keep my hands on the risers endlessly though this although my oil filter is very hot. The temp of my exhaust water does not increase (once up to operating temp) even though my temp gauge rises to alarm. I have had my manifolds off within the last 6 months so no rust build up in them. No water in my oil. Fresh oil change.
The only thing that helps is if I open the thermostat housing drain and let water flow into the bilge the temp will come down and run within normal range. I found this by accident but it is not a reasonable thing to flow seawater into your bilge when in the water. Bloop...bloop
I am out of ideas. Any help you can give would be appreciated.