PARADOX

525, closed cooling.
Had this heating Gremlin for a while. Can't figure it out.
Motor is getting hot, or hotter then it should be at higher RPM's.
Headers gets pretty warm to, Not just warm "to the tuch".
At RPM's above 4000+- motor temp gets to 175+-.
At iddle gets back to 145, but headers still remain hot.
All hoses and raw water ways are clean, no ristrictions. Headers water flow good. Outdrive water intake line, clear. Impeller is new.
T. stat? Oil cooler cloged? getting oil warm - motor warm. water hot - headers/engine hot? Oil pres. good. Raw water circ. pump? Motors have about 150 hours. 2007 model.
Flow from exh. tips .. good.
Help. I ran out of things to check. (did not replace T. Stat yet.)

Thanks. From Confused $ Frustrated P.

ezstriper

how much over 175 ? closed cooling systems generally run 15-20 deg hotter than std cooling....you are now just cooling the coolant...vs cool water all the time, and most manufactures run then hotter anyway for better economy and they don't have to be concerned with salt in the water cyrstalizing at over 150 deg.

PARADOX

Didn't run the boat long enough to get over 175.
Starboard motors runs 140 -145 at all RPM's.
Port motor (the one giving me troubles) also ran 140-145 at all RPM's.

ezstriper

did you change anything before the higher temps ? I would change the thermostat first, also if it's old the heat exchanger can become clogged and not work well, did you try switching the sending units just to be sure the temp is correct ?

boatingbent

If that motor has ever had a messed up impellar I have seen chunks of rubber get stuck in the system .....When things get stuck in the system it will run fairly cold at Idle but under higher RPM`S the water will not flow causing it to get hotter......Take all your Water Hoses off and flush and see what you might find

PARADOX

Thanks.
All hoses were taken off. Never had a impeller problem. Just changed it often just in case. Impellers were always OK. No broken peaces.

Heat exhanger is clean, interior ports are clean. Took off end caps. etc. there is NO restriction in the raw water lines.

T stat will have to be checked. Didn't get there yet.

Young Performance

Do you have water pressure gauges? If not, hook up some temp. water pressure gauges and see if there is a difference in the two engines. You could have a blockage in the gimble. The plastic fitting in the gimble that holds the water hose in place has a tendency to collapse and plug up the hole, restricting water flow. You will need to check the raw water side.
Also, I have seen circulation pumps cause overheating problems in closed cooled engines. I had one that looked perfect and seemed to be pumping just fine. After exhausting every other option, I changed the pump and that fixed it. I never did find anything wrong with the pump. I would not have believed it if I hadn't seen it. Good luck.
Eddie