Seems like a big problem. My mercury 150 outboard is making a loud clicking noise that happens at idle and goes quicker as I speed up. The engine is also overheating pretty bad. Any ideas? I changed the lower gear oil and it was clean and replaced the spark plugs. I'm looking for some places to start check for the problem. As always, thanks for the help.
It is hard to diagnose a clicking noise without actually hearing where it is coming from and what it exactly sounds like. If you are lucky, it is just a bad water pump and so I would suggest that you replace the water pump and see if that stops the clicking sound and the overheat condition. If it does not, then it may be the motor (failed bearing, knocking piston rod, broken piston ring, etc.) and I'll leave it to others with more experience in that area to suggest how to troubleshoot engine knocking sounds.
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1996 Mercury 150HP V6 carbed outboard motor and Maxum 1900XR bowrider boat
Are the water pump and the impeller one in the same? I am getting the same constant stream of water out the back of the engine. Also, after running at idle of just abouve for a while, the engine gets real rough.
The impeller is part of the water pump assembly. It is made of rubber and may be replaced alone or the whole water pump assembly may be replaced. For all the effort involved in removing the lower unit and disassembling the water pump to get to the impeller, some just go ahead and replace the whole water pump assembly if there is any doubt as to excessive wear on any assembly parts. This costs a bit more in parts, but the potential cost of a blown motor (due to failed water pump) makes the added cost of replacing the whole assembly seem minor. Just my thoughts...
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1996 Mercury 150HP V6 carbed outboard motor and Maxum 1900XR bowrider boat
Couple more things about the problem:
It gets hot at high rpm but stays very cool at idle
The noise sounds to be coming from the engine head and not the lower unit
and mabye knocking is a better term then clicking.
I'm worried it sounds like a piston issue, but not sure if that would cause higher temps?
Mercury 150 hp making a loud clicking noise
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