Mariner woes

[Johnshan1]

I took a compression reading on my '86 Mariner 30 hp today and it was 100 psi and 115 psi- it was 125 on both when I bought it 2 years ago. <br /><br />I pulled the head off and found that the top cylinder has some scoring in it, and the head itself has 3 or 4 pits where debris have hit it- ditto for the piston top on that cylinder. <br /><br />Im very worried. <br /><br />Should I do a complete tear down, and hoan out both cylinders and replace all gaskets? <br /><br />I dont know what is going on, if perhaps I caught a bearing issue before a total meltdown occured. <br /><br />I overheated the motor 2 days after I got it 2 years ago- it seized, after it cooled down it started and ran fine since (after I replaced the h2o pump of course). <br /><br />Perhaps this is where my scoring has come from? <br /><br />I need some help with this so please let me know what you would do if this was your motor. <br /><br />-John

 

[DJ]

Re: Mariner woes

johnshan1,<br /><br />I feel for ya. Bad news is that it won't heal itself.<br /><br />I think I'd go into it before it completely grenades.

 

[Johnshan1]

Re: Mariner woes

<br />

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<br /><br />Tell me what you guys think I should do.<br /><br />I have no reverse on this motor the gear is gone so keep that in mind. It is also a manual start.<br /><br />-John

 

[DJ]

Re: Mariner woes

johnshan1,<br /><br />Yep, that cylinder got a bit hot. As I said before, it won't heal itself. It's starting to throw up its insides.<br /><br />You can probably figure it's going to cost at least $2-300.00 per cylinder to rebuild. The lower unit is anyones guess.

 

[Johnshan1]

Re: Mariner woes

When you say rebuild you imply new pistons and boring/re-conditioning of the cylinder walls correct?<br /><br />I have rebuild many 2 stokes, just not in a boat motor <br /><br />So that does in fact look like overheat damage to you? The top cylinder is the damaged one, the bottom seems okay.<br /><br />If its heat damaged I will rebuild it- if its anything else (like a crankshaft) I will problably pass on it.<br /><br />Thanks a lot for your help,<br />-John

 

[Johnshan1]

Re: Mariner woes

^

 

[Johnshan1]

Re: Mariner woes

Top crank bearing was cracked and fell apart, and the rings on that one back piston were only 1/2 there!<br /><br />The middle crank bearing is a touch on the rough side, should I replace it?<br /><br />Where can I get crank bearings online?<br /><br />Also where can I get a complete gasket set online?<br /><br />Should I replace both pistons or just the bad one?<br /><br />Thanks everyone.<br />-John

 

[Johnshan1]

Re: Mariner woes

should I replace both pistons or the bad one alone??

 

[DJ]

Re: Mariner woes

John,<br /><br />I would replace both pistons.<br /><br />Any bearings that are even suspect, should be replaced. The most important thing to look for is crank damage. If it's OK, you're lucky and it should be fine.<br /><br />You are also looking at replacing the head. <br /><br />Those imperfections will glow and cause detonation. You might try here for a head:<br /><br />www.twincityoutboard.com<br /><br />Not sure about Mariner parts on-line.<br /><br />Someone will come along with a link for you.

 

[rickdb1boat]

Re: Mariner woes

Parts. You will need serial number.<br /><br /> web page<br /><br />And<br /><br /> mercruiserparts.com

 

[Johnshan1]

Re: Mariner woes

Thanks for the info guys,<br /><br />those websites are awesome as well!<br /><br />The crank has a broken bearing on the end of it- it was cracked when i took it out and it fell apart in my hands.<br /><br />The center bearing between the rods is a little iffy- it sounds like its alright but I will have someone look at it.<br /><br />I know you guys dont like this: I will re-use the head- just take sandpaper and clean it up smooth again on the inside.<br /><br />I have done this to numerous 2 stroke snowmobile motors (high HP, 9,000 RPMS for maybe 20 min at a time) no failures in 2 years. <br /><br />Besides, the head only has a few marks on it- very small at that.<br /><br />Thanks for the help all.<br />-John

 

[Johnshan1]

Re: Mariner woes

anyone know a place to get cheap crankshaft bearings? Those websites are almost $100 per bearing! In particular the upper and lower for a mariner 30M ?<br /><br />Thanks a lot<br />-John

 

[Johnshan1]

Re: Mariner woes

^^

 

[Johnshan1]

Re: Mariner woes

The bearing is labeled: "6306 NY-9"<br /><br />can I goto a bearing supply house and tell them I need that bearing? Will it be the same? I am sure it will be cheaper than $100 per bearing.....<br /><br />Thoughts? Thanks<br />-John

 

[Jammu]

Re: Mariner woes

And remember that Your Mariner is a Yamaha.... <br />Ask Your Yamaha dealer also for parts prices, they can be cheaper.<br />Your Mariner is a Yamaha 30A model, made in Japan.<br /><br />Remember to check the thermostat!

 

[Johnshan1]

Re: Mariner woes

Thanks- its strange it is even labled as a Mariner- EVERY single part has 1-2 yamaha symbols on it! Fine by me- my fav outboard is Yamaha anyways.<br /><br />I have tried finding yamaha bearings for it as well- I will just call the dealers here and see what they say- thanks a lot<br />-John (with ordered pistons on backorder )

 

[rickdb1boat]

Re: Mariner woes

John, definitley try a bearing house first. Should save you plenty..

 

[jim dozier]

Re: Mariner woes

If you feel you must re-use the head dont just use sandpaper, get a dremel grinder and grind and polish it down smooth and as even with the surrounding area as possible.