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overheating issue

M

mreider

New member
I own 125hp Mariner, I don't know what year (my # 0G074217). The alarm sounded steady on several occasions after high speed operation in 90 degree water in the Florida Gulf. Impella was replaced last season and a strong stream of water is draining. Opperating without a thermostate. Any suggestions about what could be the cause would be appreciated.
 
Did you install a restriction washer in place of t-stat?? If not water is flowing thru engine to quickly to correctly cool it at WOT.
 
faztbullet said:
Did you install a restriction washer in place of t-stat?? If not water is flowing thru engine to quickly to correctly cool it at WOT.
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I'm missing something here. Water moving too fast through engine should remove heat too fast, resulting in engine running below optimum operating temperature.
 
Water moving too fast through engine should remove heat too fast, resulting in engine running below optimum operating temperature.
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It will semi cool at idle and low speed but at WOT the water flows to fast to absorb any heat
 
It not a whacky theory as any engine that uses a poppet and t-stat combination will overheat at WOT with t-stats removed...need to get more manuals and get up to date.:rolleyes:
 
faztbullet said:
It not a whacky theory as any engine that uses a poppet and t-stat combination will overheat at WOT with t-stats removed...need to get more manuals and get up to date.:rolleyes:
Click to expand...

That might explain my one data point - since I don't have poppets.

My skepticisim is based on very simplistic thermodynamics - heat from the engine components transfers to the cooling water based on the temperature differential between the cooling water and the engine components, independent of the velocity of the cooling water. There must be something else going on.

I looked at a couple of the auto sites and the same argument has taken place. Some explanations there, on both sides of the argument, but, since my last thermo courses were some 50 years ago, way over my head.

For now, I'll just run with my thermostat installed, since motor just runs better with it in.
 
Back several years ago I built a couple of hopped up 350SBC for some buddys that ran dirt track in Clarksville ,Tn. We chased some overheating issues but the fix was to cut down the vanes on water pump,this slowed the water thru cooling system so radiator could do its job.We tried extra fans,bigger fans,smaller fans with more blades,full and half shrouds,with/without t-stat, used water wetter, etc and the cutdown vanes and washer with 3/4 hole worked best
 
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