Mercury 1500 exhaust port crack

**Gmcviper** · 10-17-2016, 06:50 PM

I was having a milky plug so I pulled power head and started taking motor apart, the #3 piston had allot of play and between the exhaust port and water jacket is cracked. Is this something I could have welded and replace the piston.

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**Gmcviper** · 10-17-2016, 06:51 PM

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**Gmcviper** · 10-17-2016, 06:52 PM

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**Mark75H** · 10-17-2016, 08:17 PM

Originally Posted by Gmcviper

I was having a milky plug so I pulled power head and started taking motor apart, the #3 piston had allot of play and between the exhaust port and water jacket is cracked. Is this something I could have welded and replace the piston.

No.

**Gmcviper** · 10-17-2016, 09:42 PM

Is there a reason why? I am going to try to weld it anyway. If it's junk already the worst that could happen is I fix it. I will probably cut out that thin web in the water passage and gouge the crack and weld from the water side. I don't think there would be a vacuum leak down the side of the sleeve, and welding from the water side that would seal water out. I would think I can get it hot enough to get the puddle to sag through and grind what's left of the crack out.

**Gmcviper** · 10-18-2016, 06:03 PM

I found a 1400 power head with a broken crank. He didn't know how it broke, but he says it is in great shape otherwise. Then I would just have to swap my crank in. Or he has some 80's distributorless 115 hp engines. Which would be a better choice.

**Capt.Insane-o** · 10-18-2016, 07:21 PM

80's block

**Mark75H** · 10-18-2016, 08:42 PM

Agreed. Its the same motor, derated for advertizing the 150hp V-6

**Gmcviper** · 10-18-2016, 09:56 PM

Well 80's motor have better throttle response than the distributor model?

**Mark75H** · 10-19-2016, 04:31 PM

No.

**Gmcviper** · 10-19-2016, 06:33 PM

What is better about the '80s engine then? I was thinking not having a distributor made it better. I read a post from a while back and you guys were talking about port timing and reed blocks. http://www.screamandfly.com/archive/.../t-185876.html I did some figuring on my 1500 the piston just clears exhaust port at 94° atdc and the piston just clears intake port at 140° atdc. That is on the down stroke, I'm not sure how port timing is actually measured. What type of reeds would my'75 1500 have vs the '80s 115?

Thanks for the help