Rebuilding Mercury 150hp V6

[Daniel1947]

Previous questions about a burnt piston were addressed and answered on Forum, once again thanks for all the responses. My progress so far is: engine has been completely disassembled, #3 cylinder has been bored .020 over, (.015 wouldn't clean #3 cylinder), other cylinders honed to break the glaze and are within specs. My mechanical expertise comes from rebuilding car engines, and if this was a car engine I would be replacing all of the rod and main bearings, however the roller bearings all look OK, as does so many other parts that I would normally replace if this was a car engine. The engine was running great, until #3 piston burnt and the engine locked up. I understand I will need to rebuild the 3 carburetors, paying close attention to #2, which feeds #3 cylinder. My questions are: how extensive or how far should I plan on going to rebuild this engine? Re-ringing the other 5 cylinders is a must, as is replacing all gaskets, etc., What about those "sealing rings" on the crankshaft? etc. As always any advice is greatly appreciated. I have the correct model motor manual from Mercury, and right now the only thing I am having difficulty finding is a .020 over piston. I checked I Boats, but it looks as if they only have .015 and .030 over in Sierra.

Dan

 

[Chris1956]

Re: Rebuilding Mercury 150hp V6

Dan, Make sure you also install a new waterpump impeller, and check the link and synch. You are trying to fix all things that might have caused #3 cylinder to fail.

 

[Daniel1947]

Re: Rebuilding Mercury 150hp V6

Thanks Chris,

I am almost 100% that the carb feeding #3 leaned out. Everything else looks OK, reeds, other cylinders, oil feed, etc., so that is what I figure happened. Water system seemed to be functioning, as was the oil injection, temerature on motor never got above mid-point. So, I will be taking a very close look at #2 carb. I really do appreciate the input.

Thanks.

 

[Faztbullet]

Re: Rebuilding Mercury 150hp V6

A 1989 motor should have the vertical reeds not horizontal, so each carb barrel feeds cylinder on same side. Usually #3 is a timing problem due to bad trigger or damaged bia's circuit in one/both of the switchboxes. After reassembly index flywheel and check timing on that cylinder. I suggest you replace lower bearing,all crankshaft seals, crank sealing rings only if sides have a groove worn in them and if you need a .020 pistom pm me as I sell aftermarket(not Wiseco) brands..