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Problems with 43 mercruiser 2006

S

stanleylee128

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"I bought a 2007 four winns 18

"I bought a 2007 four winns 180 with a 4.3 mercruiser turn key start carby motor 190hp. It only has 30 hours on it. First I found 2 bend valves on the left side head, so had it removed, repaired and bolt back on. Check compression, all good. It was running fine until the temperture alarm goes off when it gone pass 3500 revs. Once I back off, the temp was good again. The motor runs fine when cold but idle very rough when hot. Also notice a flat spot under 2000 rpm. I clean the carby twice already and is still running rough. So there are 2 problems, idle rough when hot and overheating on hi revs..........Any idea would be appreciated. Thanks."
 
Is the impeller in good condit

Is the impeller in good condition? Does the throttle open all the way when hot? What is the condition of the spark plugs?
 
"Hey Guy! Tried your email and

"Hey Guy! Tried your email and was unable to get thru. Please contact me. Thanks, Al W."
 
"The spark plug are new, just

"The spark plug are new, just had a serviced before finding the bend valves. Impeller is also in good condition. Throttle opens all the way even when hot."
 
Is the engine overheating when

Is the engine overheating when the alarm goes off? If not the water flow sensor could be defective. Carb may need replacing.
 
"yes, the alarm goes off when

"yes, the alarm goes off when temp goes over 175. Where is the water flow sensor located? I might check that too. Is it common that the mercarb have many problems, I see replacement carb for sale on ebay, are they ok? do you have a prefer carb which you may suggest? thanks Guy."
 
"WOW almost hard to believe th

"WOW almost hard to believe the engine was in that bad of shape, Did you check the fuel to see if it's Bad, old, water, ect???

What is the history of this boat?

Do you have a engine serial number?

Have you checked the timing while in base timing mode? And also have you checked the advance timing while in normal mode? Does the timing move up while reving the engine?

How were the valves bent? Or were they tuleped?

Have you pulled out the Impeller and checked the impeller and impeller housing area for any damage of any kind?"
 
Stanley:

Since the engine i

Stanley:

Since the engine is overheating there are several things to check. Is the boat run in saltwater? Does it have fresh water cooling? Boat Tech says impeller and so do I. T'stat stuck closed? Engine circulating pump working; loose belt or broken shaft?

If Raw Water Cooled remove the water inlet hose from the T'stat and point it to a bucket. W/a water supply attached to the leg run the engine 30 seconds; it should fill a 5 gal. pail quickley.

You can get a carb. kit to rebuild yours or buy off of eBay.
 
"The boat was purchased from a

"The boat was purchased from an auction. First thing I did is to have it service and thats when I discover the bent valves, no idea how it happen. The fuel is fresh, no water. I guess its my bad luck. Anyway, The engine is raw water cool. I will try to test the water pressure, check t'stat and water pump. Thanks."
 
"Thank you. I got the carby p

"Thank you. I got the carby problem sorted, it turns out to be a broken base gasket and dirty power valve. I still have the overheating problem though. I had a brand new water pump impeller kit put in, checked the t'stat and the risers, all in very good condition. The overheating problem started after the head was refitted. I seems to think that has something to do with it....Can the head gasket be put in back to front or upside down blocking water passage?"
 
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