Mike L

I have a 540 Dart with AFR heads engine with no water thromostats in it. Both motors always run just at 100-110 degrees with the water temp, oil thermostats keeps it at 190-210. The problem happened middle of last year one motor when cruising the water temp climbs to 150-160 unless I go 65+ it starts to cool back down, assuming more water pressure. The boat did not have strainers on it until this year and now i can watch the strainer on the port motor not able to keep up even at an idle. I have checked into everything. Off course it has a brand new water pump on it and never has burnt an impeller, only has 50 hours on the motors. It has a power steering cooler which is clean and it has a hardin oil cooler which I took off and split and it is perfectly clean. It has imco boxes with XRs and i took access plates off and i can access the hose at the fitting to the drive, took that apart and ran a camera through it and it looks fine, backwashed everything anyways. The only thing that is left is possible inside the motor there is a clog??? I am out of options and have completely checked the cooling system except the block itself. I would think looking at the water coming into the strainer that it would be clogged from the drive to the strainer because it is not nearly as heavy of flow as the other side, but it may just be no where for the pump to pump to as well??

Mike L

Could there be something stuck in the drive itself? Fromt he fitting ont he Gimbal to the pump it is clear. I have blown water from the fitting through the drive and it seems to blow through fine. I can take the plugs of the block and blow water through the thermastat houseing but I dont think It would clear it because it is pumped though harder then that. I truely am out of ideas.

Mike L

Found it I think. Bad seal on shaft side of water pump, sucking air. Perfect on hose so we shall see this weekend.

My Addiction

Also, you should be able to rule out the motor being clogged b/c the pump and sea strainer are before the motor. If it were the motor your strainer would be filling up and possibly building excessive pressure. Sounds like your on to something.