# Mariner 25hp advice?



## chbarnha (May 14, 2018)

Just recently acquired this motor that came on boat in my new boat thread. It came on a 16ft xtra wide john boat that I obtained for 2 cases of beer. I have been looking on the net and cant find much on these motors to be honest. Are they decent motors? anything I need to look out for specifically on this motor? Thanks in advance guys, never had anything but johnsons. Its a mariner 25hp, and I know im a need to do the water pump and the plugs. Its been sitting about 7 years.


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## richg99 (May 14, 2018)

Pappy, on this site, is a guru on older motors. The Mariners were, to my very limited knowledge, built by a variety of manufacturers over the years. I don't believe that Mariner every actually built a single engine on their own.

Might be a Yamaha, might be a bunch of other builders. The serial number tells all.


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## nytebyte (May 14, 2018)

The stripes on it look the same as my 20 hp mariner and that was a 1988 motor with a yamaha powerhead. It was a great motor, still is. Sold it to my son. Jim


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## GYPSY400 (May 14, 2018)

I believe ( feel free to correct me) that mariner of that vintage is Yamaha power with mercury electrical.. not sure about the bottom end.

DO the water pump, plugs and a carb kit and you should have no worries.

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## chbarnha (May 14, 2018)

Glad to hear that it should be good to go with that little bit of maintenance. One of the other guys in the club was saying that mariner motors were trash and there was no point in trying to get it running because they usually didn't last long. Was a little worried and thought about throwing my 35johnson on the back, but seeing that they may not be that bad, I think im a get this running and leave it as it sits.


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## onthewater102 (May 15, 2018)

I've got the same motor on my rig and after tuning it up 4 years ago I haven't had any issues with it that weren't routine maintenance type items.

Make sure you have spark and compression on it, if you do then anything it might need should be a relatively inexpensive fix.


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## GYPSY400 (May 15, 2018)

chbarnha said:


> Glad to hear that it should be good to go with that little bit of maintenance. One of the other guys in the club was saying that mariner motors were trash and there was no point in trying to get it running because they usually didn't last long. Was a little worried and thought about throwing my 35johnson on the back, but seeing that they may not be that bad, I think im a get this running and leave it as it sits.


He might be confused with Force motors.. not too many good reviews on those.

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## Zum (May 15, 2018)

Looks like a Yamaha made Mariner.Tough motors,I have a 30hp 1987 model...ive done very little to the outboard, impeller kit being the only maintenance. 
Where I'm at, it's cheaper to go to Yamaha for parts , mercury has the same kit but 80 bucks more...but maybe that's just the place I was dealing with.
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## muddywaders (May 15, 2018)

In what fairy-tale land can you buy a decent boat and motor for two cases of beer?I wish to move there or maybe not since a case of beer costs $500 !!!
The motor in question is a Mercury built mid 80s - 90s.Good motors as were the Yamaha Mariners however, some of these did not come equipped with thermostats(Mercury built)and have chrome-lined blocks which cannot be bored over.If you decide you do not want this motor I will glady trade you a case of Pabst blue ribbon.mw


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## chbarnha (May 16, 2018)

I got it from two older guys I hunt with. They hadn’t used it in years and told me if I wanted it I can have it. Can’t beat that deal for sure.


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## chbarnha (May 20, 2018)

I’m having trouble finding the year for this motor, anybody good with the serial numbers. I may have just missed it but not sure. Serial number is 6634766. 
The guy I got it from said it wouldn’t run. Me and a buddy got to messing with it, it has 125lbs compression in both cylinders, and cleaned the plugs up. Took the carburetor apart and just need to get the gasket kit and the water pump for it.... it does run. The kill switch was shorted out, we disconnected it and she fired right up and run long enough to tell it will run.... making progress just need to order the parts.


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## chbarnha (May 20, 2018)

Also im trying to find where to get the plastic push pull primer housing.... it was brittle and when taking the motor apart the cracked. Trying to replace it but may be able to make it work if its a hard part to find. Any ideas?


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## richg99 (May 21, 2018)

I'd take pictures of it from every angle and then copius measurements. If you can't find where to buy it, then you might have one of the 3D companies make one for you. 

There is an Antique Outboard Motor site. You might ask there for a source.


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## turbotodd (May 22, 2018)

Looks more like a Mercury built Mariner than a Yamaha-built Mariner. The Yamaha-built motors had a serial number sort of like 689 (or S) XXXXXX, where Merc built motors just had a number, sometimes with a letter thrown in. I also remember the carb being more centered; but it's been a while since I messed with one-which was mostly a C25 or C30 yamaha. The C25 and C30 are the same block, actually most of the motor is the same and a C25 can be converted to a C30-I just don't remember how.

If it's a merc engine, do a compression test first thing. They are known to delaminate the chrome lining from the cylinder walls, and as mentioned, there's no fix other than block replacement. I "think" there was a company who can re-line them but I'm not sure on the cost as to whether it'd be worth it or not. Worth looking into only if you have to. Hopefully not. Google search "mercasil block"-or something similar. Mid 1990's is when I got out of the Mercury business, thank goodness. Brunswick didn't like to pay warranty claims, or wasn't at the time, and for that and other reasons, we let them have their garbage back. We were a Yamaha powersports dealer, so it just made sense to start carrying their outboards, and we sold thousands of the 25hp 2 stroke/twin carb models. Every duck hunter in the area had one. They weren't as fast as the 3 cylinder model, but they were LIGHT, smooth running, and reliable enough even for duck hunting in flooded timber. The "mercury" guys (includes mariner) liked the Merc/Mariner for one reason, and one reason only. Shift in the throttle grip. I personally hate it.

For what you have in it, it'd be worth messing with as long as the compression is 90 psi or greater.


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## chbarnha (May 23, 2018)

We ran a compression test on it a week ago, both cylinders were between 120-125. Got it running in about 30 min. The kill switch was shorted out and that’s why they never got it running. Went and picked up the carb rebuild kit and impeller today, hopefully have them done by the weekend


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## onthewater102 (May 24, 2018)

While you have the carb off take a look at the reed block and adjust it if necessary.

See my post on this motor and the issues the reeds can cause:

https://www.forum.tinboats.net/viewtopic.php?f=4&t=43303&hilit=reed


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