Cooling Problem
 

I have a 30' Scarab with twin 7.4 Bravos. When I went out this weekend, one motor is running at 150-155 degrees, the other is fine. I changed the thermostat, but no luck. The housing is the new stlye, cast iron, and is getting pretty nasty, but seems to be unobstructed. The engines use circulating pumps, could that be the problem? I can lay my hands on the risers, so I do not think that's the probelm, but would appreciate any advice. Thanks.

When was the last time you replaced the Impeller in the Raw Water Pump(s)?

Almost 3 years ago, but I have good water flow through the exhaust.

150-155 temp is fine .....thermostat is 145* ....what temp is the other motor?

Both motors have 140 degree thermostats, the other motor never goes above 140. The temp on the motor in question has been rising over the last year very slightly up to this 150-155 level. Manifolds and/or risers?

3 years ago? That's your problem. Impellers need to be replaced every year. More often if you are in a really dirty river or lake. :lolhit:

Replace the impeller--in both engines. There is probably a vein broke off on the one with higher temp that is restricting water flow just a little.

Thanks! You guys convinced me. Any tricks on rebuiling the pumps, or do I just need to replace the impellers.

Not sure where to get it online, but i got mine from a local guy. It comes as a kit with new bolts, impeller, gasket, and housing. The housings are plastic aand wear with the impeller! just make sure you twist the impeller in the right way. Good luck

doesnt matter on the rotation ..it will flop around if you get it wrong .....lube it up good ....