Buy a 5hp Mariner with a blown head gasket?

[kalebsheridan]

On the market for a kicker motor and found a mid 90s Mariner 5hp with a blown head gasket for $100. Looks pretty clean. Is this worth a look or should I keep looking elsewhere? Never done a head gasket and not sure if this would be indicative of more damage elsewhere. Thanks all.

 

[Chris1956]

A new head gasket for a 2 cycle motor is real easy, provided fresh water use. However, a bad head gasket could be a symptom of some other damage. It sounds like you should pass on that one.

 

[racerone]

How do you know it is a " blown head gasket " ??----Sellers guess ?----If it truly is a blown head gasket and clean it might be a good deal.----There are different models.----Even an air cooled one.----Any idea of serial # or a picture?

 

[kalebsheridan]

Actually turns out it isn't a blown head gasket. It's a "head plate" gasket or something. So he said it has some broken bolts and a bad gasket on the head. He sent photos and clarified that it's the gasket under the exhaust cover (what he called a head plate", and the broken bolts are the exhaust cover plate bolts. Id have to extract those bolts but if the compression and spark are good I suppose I'll buy it

 

[kalebsheridan]

 

[cyclops222]

You can find a much better motor.

 

[racerone]

That appears to be a Yamaha built motor.-----Some will say that they are the best !

 

[kalebsheridan]

Welp I bought it. Everything looks to be in working order. The catch is the guy the seller bought it from must have tried to change the thermostat and broke 3 bolts to the exhaust cover in the process. I ordered some extractors to remove the stuck bolts. Any good way to find parts for these? I don't see much when I look up Mariner but I see a lot when I look up Yamaha. Is there an equivalent Yamaha model to these? I believe this is an 82 mariner. I just need a thermostat and the gaskets really. Everything else looked fine.

 

[racerone]

??----Find the parts at a Mercury dealer.-----Find the parts at a Yamaha dealer.---Boats.net ---online has good prices.-------Your choice.

 

[racerone]

I would make a dummy exhaust cover to use as a drill guide.------Drilling a steel bolt in an aluminum housing can be tricky without a drill guide.

 

[kalebsheridan]

Copy raceroni. Yeah I just found some websites service some makes better than others so I was curious. I found what I need at crowley marine. Should I buy replacement gaskets or can I just make them? I have lots of gasket paper. Good idea on the guide idea too. I'll do that.

 

[boscoe99]

What is the engine serial number?

 

[kalebsheridan]

What is the engine serial number?

6e3s129829

 

[boscoe99]

Looks to be a 1984 model year motor.

Would be the equivalent of a 1984 Yamaha 5LN or 5SN.

 

[kalebsheridan]

Looks to be a 1984 model year motor.

Would be the equivalent of a 1984 Yamaha 5LN or 5SN.

Sweet thanks boscoe! Looks like I can even get the same busted screws. Is it worth actually buying the exhaust plate gaskets or would making some gaskets suffice? I have automotive gasket paper.

 

[cyclops222]

You can do a simple gasket repair job. Leave the broken bolts in the cylinder head. If that plate is ONLY holding in EXHAUST pressure or INTAKE pressure ? NOT full combustion pressure ? You can simply use a THIN coating on the area of the 3 holes. NOT a messy coating of each surface !! just enough to provide a good seal if only about 5 or 10 THOUSANDS of distortion is there. I would lightly only coat each surface under the 3 bolt holes plates. press firmly together to ooze out excess sealant. Take all apart to remove squeezed out beads. Do it until there is no more oozing out of sealant. Correct amount of sealant is when you separate each part & gasket . You see pointy sealant spikes on all surfaces. Then assemble everything permanently. Start the engine at low speed. after a warm up. Stop and check sparkplugs for water. NONE Good job. You will always worry a little untill several hours of running time is completed.

 

[Chris1956]

If you can get a vice grip on the broken bolts after you pull the head, they may come out. use some heat and then remove the heat and spray with penetrating oil and let cool. Repeat a few times. As the bolt cools they can suck in the penetrating oil, helping to loosen them. Then try the vice grip.

 

[boscoe99]

Sweet thanks boscoe! Looks like I can even get the same busted screws. Is it worth actually buying the exhaust plate gaskets or would making some gaskets suffice? I have automotive gasket paper.

I suspect that you know what you really should be doing.

 

[kalebsheridan]

You can do a simple gasket repair job. Leave the broken bolts in the cylinder head. If that plate is ONLY holding in EXHAUST pressure or INTAKE pressure ? NOT full combustion pressure ? You can simply use a THIN coating on the area of the 3 holes. NOT a messy coating of each surface !! just enough to provide a good seal if only about 5 or 10 THOUSANDS of distortion is there. I would lightly only coat each surface under the 3 bolt holes plates. press firmly together to ooze out excess sealant. Take all apart to remove squeezed out beads. Do it until there is no more oozing out of sealant. Correct amount of sealant is when you separate each part & gasket . You see pointy sealant spikes on all surfaces. Then assemble everything permanently. Start the engine at low speed. after a warm up. Stop and check sparkplugs for water. NONE Good job. You will always worry a little untill several hours of running time is completed.

So the gaskets in question are the ones between the inner and outer exhaust covers. That whole sandwich seals in the exhaust intake and housing for the thermostat. If your solution will still work under this situation then I'll totally try that if I can't get the broken bolts out. I have 6 of the 9 bolts intact too. I just ordered a left handed screw and extractor set so I may need to try your solution if the extraction fails.

 

[kalebsheridan]

If you can get a vice grip on the broken bolts after you pull the head, they may come out. use some heat and then remove the heat and spray with penetrating oil and let cool. Repeat a few times. As the bolt cools they can suck in the penetrating oil, helping to loosen them. Then try the vice grip.

Unfortunately they snapped pretty clean. I'll try the penetrating oil treatment while I wait for the extractors to come in the mail.