Buy a 5hp Mariner with a blown head gasket?

Chris1956

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Mar 25, 2004
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Precision drilling is a wonderful thing. It is difficult to drill out the harder steel, while not molesting the softer aluminum. Good job, and good luck on the others.
 

cyclops222

Ensign
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Mar 21, 2024
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I have never seen a bigger pile of odd ball castings in my life. The very bottom of the gasket area has no sealant there. Good luck on that engine. (y)(y)(y)
 

kalebsheridan

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Aug 14, 2023
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Welp I got all the bolts drilled and tapped. 5 in total. 4 came out real nice, I was basically able to pull the old steel threads out, which made lining up the tap super easy to finish the job. One I messed up pretty bad. I tried those EZ-outs. I'll tell ya, there's nothing "EZ-out" about those when they break off in a bolt. I had to buy a tungsten carbide Dremel tip and painstakingly grind out the ez out tip. In the process I knocked my hole off center and messed up the threads in the block. I might have a handful of good threads in that hole after it was all said and done. I guess I'll just have to be real gentle on that bolt. Better than no bolt I guess. If anyone reads this because they found themselves needing to drill out broken bolts in a powerhead, don't bother with the ez outs. Get some some left handed drill bits if you want since you gotta drill the hole anyways and maybe you have a chance of backing the sucker out, but those chances are slim due to the steel and aluminum basically fusing to each other. I maybe spent 45 minutes drilling and tapping each bolt, and breaking off an EZout basically quadrupled that. Even attempting the extraction with an ez out without snapping it was a waste of time. Maybe in the future I'll use a drill press to size up the hole to accept a 6.5 or 7 mil bolt. I suppose this will do.
 

kalebsheridan

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Did you read post #10 on the drilling ????
I did but I figured without a drill press I may not get precise enough holes on the dummy plate to match up anyways. Plus I messed up the last bolt hole trying to dig out a broken extractor, not so much by drilling the hole. If I get a drill press however I will do that in the future. That would have helped a lot to guide the drill bit down without wandering.
 

kalebsheridan

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Aug 14, 2023
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Welp I got the gaskets in the mail. The two exhaust plate gaskets don't fit. Like they shrunk some how. Part number matches and everything. Perhaps I can find gasket sheet material that's a similar material and make a gasket for that.
 

kalebsheridan

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So I found some rubber fiber gaskets material and cut out some gaskets. They turned out pretty good I think. Put the motor back together using some light permatex sealant to help the homemade gaskets stick. I don't have my gas tank with me to fire up the motor but it did turn over with some starting fluid. When I get some fuel and my tank I'll fire it up and see how she runs. What's a good idle RPM for this motor?
 

Chris1956

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Mar 25, 2004
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27,659
That gasket looks real good.

You need to find out why the ones you bought didn't fit. Maybe they sent the wrong ones, or you have a number wrong? You probably want to find out before you need more parts.

Maybe you could take them to a Merc dealer and see if they match his stock or something.
 

jimmbo

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May 24, 2004
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13,269
600 rpm, give or take 50 rpm. I like to go as low as practical, as it is easier on the Shift Mechanism, which is either In or Out of Gear, no slip Clutch to ease in
 

kalebsheridan

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That gasket looks real good.

You need to find out why the ones you bought didn't fit. Maybe they sent the wrong ones, or you have a number wrong? You probably want to find out before you need more parts.

Maybe you could take them to a Merc dealer and see if they match his stock or something.
That's a good idea I still have the ones they sent me. I'll see if they actually sent me the right ones. I noticed when I bought them off cowley, when I click on the mariner model, it automatically sends me to the equal model Yamaha. Maybe that has something to do with it. Better find some more gaskets since I'll need new ones every time I do a thermostat.
 

Chris1956

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Mar 25, 2004
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27,659
You could try marineengine.com, ebasicpower.com or iBoats. Maybe they list another number.
 

kalebsheridan

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So I got the motor hooked up to fuel and water. Fires up but doesn't idle for long at all. What's a good carb setting? My initial thought is it's a carb adjustment issue.
 

jimmbo

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May 24, 2004
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A good Carb Idle Mix Setting, is one that Idles well and is Rich enough to prevent a Bog/Stumble when Accelerating. There is an Initial Setting, on the Rich Side, but still within a Combustible Range. The Correct Float Setting is Critical, as it sets the Fuel Level, and too low or too high will certainly affect how every Fuel Circuit in the Carb behaves
 

kalebsheridan

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Okay, I guess I was refering to an initial air mix screw setting, but I'm gonna pull the carb again and do a deeper clean. The fuel pump is marginal too. The diaphragm is a little crispy. I'll double check the fuel bowl again. I know the float needle looked new
 

jimmbo

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The diaphragm is a little crispy.
A another added Tidbit, that would have been nice to be told about initially

I'll double check the fuel bowl again. I know the float needle looked new
A nice New Inlet Seat and Needle can still provide the wrong Fuel Level if not set Correctly, or the Float has absorbed Fuel.
What condition is the Float? Is it Cork, hollow Metal, or a Plastic Material? All of the above can absorb Fuel and thus be heavier than spec, and that affects Fuel Level too
 

kalebsheridan

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Yeah I wasn't sure how bad it really was, but I have another motor I'm working on that does have bad diaphragm and when I compared this old one to the other motors new one then I could tell.
 
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