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2007 4.3 L mercruiser overheating

Jeffrey 9898

New member
I am hoping you can help me. My 2007 4.3l carberated engine started to overheat last weekend. I replaced the water pump in the lower unit, the impeller was pristine but I replaced it any way. There is no water getting up to the thermostat. The overheat alarm sounds with a cold engine as soon as I start the engine. The boat is only used in fresh water and I am the original owner. Hope someone can help.

Jeff
Mashpee, MA
 
Re: 4.3l mercruiser overheating

What type of drive?
transom water hose disconnected
water pocket cover destroyed
backflush from the hose at the therm housing to the drive, see where the water comes out.
 
Re: 4.3l mercruiser overheating

Bt Doctur it is an alpha drive. I am not sure what you mean by the transom hose or the water pocket cover ? I will backflush again right now and report back. Thanks!
 
Re: 4.3l mercruiser overheating

Water comes out of prop, just above lower unit facing forward, and from two port at base of the drive where it connects to the hull.
 
Re: 4.3l mercruiser overheating

OK I chased down the water pocket cover which of course I did not check. I will research how to remove in order to inspect. If the transom water hose was disconnected would the water be running into the engine bay? I am not having that problem if that is correct.
 
Re: 4.3l mercruiser overheating

Hows that saying go,"never enough time to do the job correctly but always enough time to do it twice."? I shall take the lower unit off again now.

Jeff
 
Re: 4.3l mercruiser overheating

So its an Alpha 1 but it does not have a water pocket cover. With the lower unit off can I back flush to the drive? I guess I really cannot understand the water flow yet.
 
Re: 4.3l mercruiser overheating

The transom water hose runs from the OD to the transom. Look under the OD, it may be kinked. If you boat in saltwater remove the water inlet hose inside the transom and see if the coupler is corroded shut.
 
Re: 4.3l mercruiser overheating

Never boat in salt water but I shall check the coupler if I can wiggle in there. I was reading another post looking for ideas and a gentleman replaced his lower drive and forgot his cooper tube. I don't have one, should I have one? 2007 searay 185 with alpha I.
 
Re: 4.3l mercruiser overheating

Yep thats what I have plus a plastic offset tube not shown in the drawing. No kinks from the OD but I cannot get at the connection inside. It comes in and does an S curve and hits a manifold then runs across the top of the motor. I just pulled the top cover off and will look down to verify it is engaged properly.
 
Re: 4.3l mercruiser overheating

Well haste or inexperience or both makes waste. Second times the charm! Just need a new gasket for the t stat manifold and I am going out. Maybe get a lotto ticket while I am out, after all I did not need the third time! Thanks all for your help!!!
 
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