Should I replace the Power head

[Dhadley]

Re: Should I replace the Power head

When looking for a used piston there is only one sign to look at. The stop sign. Your cylinders will be very much out of round and most likely out of spec. Do not buy anything until you hace the motor apart and the machine shop measures it with a dial bore gauge. <br /><br />What spark plugs were you using?

 

[ehaskins]

Re: Should I replace the Power head

I second Dhadley ( Not that he needs it ) When piston melts down generally when you look at the head it will have what looks like melted BB's all over it. Not to mention the heat the cyl wall took. Cyl should be measured with micrometer in different spots to check if its true. New piston will run around 80.00 depending where ya buy it. <br /><br />Bad side if you need to bore that cyl. (we do it for 40.00 +/- per cyl) you are going to need to strip motor down to the block. Still that route buy 3 more pistons, gasket set and almost brandy new <br /><br />Eric

 

[Hooty]

Re: Should I replace the Power head

Like Dhadley said, get busy. I just through replacing the crankshaft in my 'rude V6. Fired it up yesterday and it never sounded better. I used the factory manual, followed it to the letter and everything went slick.<br />Go for it.<br /><br />c/6<br /><br />Hooty

 

[waterdowg]

Re: Should I replace the Power head

I just got a new piston and ring for $25. Gotta love ebay. <br />I was thinking about the the engine over heating if the engine got to hot wouldn't the #1 piston melt first since the top of the block would get hotter. Or Could the water flow have been blocked and not allowed the water to cool tthe #3 piston.

 

[Dhadley]

Re: Should I replace the Power head

What you are describing is coking damage. It is from combustion heat, not water temp heat. If you check the hardness on the other pistons you will most likely find most of the hardness gone. The most common cause is from lugging the motor. <br /><br />What piston did you end up with?

 

[waterdowg]

Re: Should I replace the Power head

I got a Wesco piston. What do you mean by lugging the engine?

 

[Dhadley]

Re: Should I replace the Power head

Which Wiseco?<br /><br />You said you could only get 5200 RPM. Thats lugging the motor and will cause the combustion temps to rise even at 3000 RPM. What spark plugs were you using?<br /><br />Be specific.

 

[waterdowg]

Re: Should I replace the Power head

I believe they are Champion plugs. As for the number I don't know off hand but they are what is recommend in the Evinrude service manual. I think I gaped them at .035

 

[Dhadley]

Re: Should I replace the Power head

Which Wiseco????

 

[waterdowg]

Re: Should I replace the Power head

I purchase the 3.5 Standard Crossflow piston. I had the cylinder looked at and was told it the cylinder walls were fine.

 

[ehaskins]

Re: Should I replace the Power head

Wiseco Piston # 3073PS for standard bore should be the piston you need<br /><br />Eric

 

[waterdowg]

Re: Should I replace the Power head

I got Wiseco #3013PS told it would fit.

 

[Dhadley]

Re: Should I replace the Power head

Thats an old part number. The new one is 3173. <br /><br />I still find it hard to believe the cylinder is in spec and doesnt need boring.<br /><br />Good luck!

 

[waterdowg]

Re: Should I replace the Power head

The shop was surprised to that it was fine. But hey there the experts.

 

[mike-evin-50hp]

Re: Should I replace the Power head

Cylinder walls can LOOK fine and be out of spec. Dhadley is right on. The cylinders must be measured, not just looked at. I had a so called "expert" rebuild my 65hp rude 15+ years ago and put stock pistons in ($1500.00) He said cylinders look fine! Blew a ring first time out. This time I bought the service manual, tore it apart myself and went to a machine shop. All 3 cylinders worn out of spec. Should never have had stock pistons on 1st rebuild. Bored out all 3 - new pistons and rings - no problems.<br />Beware of some so-called experts.