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Overheating 2007 mercruiser 5.7 mag mpi

D

driver_to

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I am having problems with my 2007 5.7 merc. It is running hot when it starts and idles, you can't hold your hand on top of the heat risers after about 1-2 min. of idle. I have replaced the impeller the water dist. hsng.(broken) and the thermostat. I have also had the engine out and replaced the crank and bearings(#7 rod brg gone). Upon removal I found that someone else had recently had the exhaust man. and risers off, I replaced the riser gskts the same way they came off but am now wondering if they were installed correctly. Does the small hole face the front of engine or the rear. any other suggestions? The boat only has 170 hours on it never in salt water. Thanks
 
small holes are front and back, larger slots are side to side
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thanks for the reply but I'm sorry I was not very clear with my original post the exhaust riser gskt. I am asking about is part # 27-864850 A02 this gskt. has no holes on the side my engine ser.# is 0W681596 the boat also has a corsa captains call exhaust syst. Thank again sorry for my inexperience
 
That would be the dry joint system and small hole to the front of the engine for sea water cooled engines
Are you open or closed cooled
 
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thanks for the info. It is an open system, and from your answer it looks like I installed the gskts. correctly. Any other suggestions for my cooling problem?
 
water in= water out need both or you overheat. being the GEN II pump when you replaced it was it the whole kit or the impeller kit.
 
I replaced it with the impeller kit only, the inside of the housing was clean no scoring and it appeared to have very little wear, I am wondering if maybe the manifolds or the risers could be blocked with rust or some foreign material Thanks again
 
Did you examine the seal under the SS plate? I just serviced an overheat from barnacles. The plastic melted in such a way it bowed the SS plate upward breaking the gasket seal. #18
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the serial # for my leg is 0W930605 and the only impeller I see is in a belt driven water pump housing on the lower rt. side of engine this is the impeller that I changed, am I missing another one? Thanks
 
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