1985 Mariner 150hp Running, but seems very tired

[Bob Moss]

Hi, Thought I would run this topic by you guys to see if you can offer any advice. I have a 1985 Glastron 16' ski boat, with a 150 Mariner outboard. I have owned the duo since summer '87, and I have never had any issues with either. My brother (225 lbs) and I (190lbs) have slalom skied behind her hundreds of times. She used to pull us out of the water instantly. With the stainless propeller, she had so much bottom end torque that we nicknamed her the stump puller. Now, she is acting tired. With a light load she will still cruise all day at 45mph, but she doesn't "rabbit" up to speed anymore. Add a few hundred more pounds of passengers, and she is much slower still. She still gets up to top speed and sounds just fine, but she doesn't do it with zest. I have had my mechanic (a good general mechanic) check her and he says that all is fine. I know it isn't, but I can't really explain to him what she used to be like. How do I go about getting her back to her old self? Are these recognizable symptons of a common age related development. I love the boat and motor, and although I am no longer skiing very often, I would like to continue to do so in the future. For now, I have to let others pull me. Thanks a bunch!

 

[KCLOST]

Re: 1985 Mariner 150hp Running, but seems very tired

Let's assume that the motor "is" ok like your mechanic says...

Is there any water in the hull, is the boat hull clean, any barnacles or stuff on it? And are you using the same prop that you always have?

 

[Kevin W]

Re: 1985 Mariner 150hp Running, but seems very tired

i have a few possibilities:
Check the compression.
it is most likely not as good as it was in the earlier days.
more compressoin= more torque = more stump pulling ability. I am sure its still useable but maybe not quite as good.

also the newer gas has ethanol alchohol in it.
10%ethanol gas does not have as much power producing ability as 100%gasoline.

It could be a combination of both things.

 

[Bob Moss]

Re: 1985 Mariner 150hp Running, but seems very tired

Let's assume that the motor "is" ok like your mechanic says...

Is there any water in the hull, is the boat hull clean, any barnacles or stuff on it? And are you using the same prop that you always have?

There is no water in the hull that I know of. The gas tank is up there, and I have no means of access. However, the attititude of the boat sitting in the water makes me think its fine. The hull is clean. It has been sitting on very clean fresh water its whole life. As for the prop. Years ago I switched to a stainless with a pitch geared towards bottom end. The boat got much stronger when this change was made. Last year I tried the boat with a spec prop and the stainless. Same net result. Thanks.

 

[Bob Moss]

Re: 1985 Mariner 150hp Running, but seems very tired

i have a few possibilities:
Check the compression.
it is most likely not as good as it was in the earlier days.
more compressoin= more torque = more stump pulling ability. I am sure its still useable but maybe not quite as good.

also the newer gas has ethanol alchohol in it.
10%ethanol gas does not have as much power producing ability as 100%gasoline.

It could be a combination of both things.

Not sure about the gas issue. I am looking to find a dedicated Mercury mechanic that will be hopefully knowledgable and honest. You are probably right about the compression, and that will be the first thing I will have him check. Short of a complete rebuild, any chance that it might be a simple fix to restore her zest? Thanks.

 

[05GlastronSX]

Re: 1985 Mariner 150hp Running, but seems very tired

de-carbon might just do the trick. use some sea foam a.k.a deep creep. Its worth a shot. It can be a cheap, easy fix.

 

[Bob Moss]

Re: 1985 Mariner 150hp Running, but seems very tired

de-carbon might just do the trick. use some sea foam a.k.a deep creep. Its worth a shot. It can be a cheap, easy fix.

That's interesting. How do you apply it? Where do I find it? Thanks.

 

[Kevin W]

Re: 1985 Mariner 150hp Running, but seems very tired

Decarbing may be a very good solution:
http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=36;gtid=1035563

here is the proceedure listed under FAQ

 

[Bob Moss]

Re: 1985 Mariner 150hp Running, but seems very tired

Decarbing may be a very good solution:
http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=36;gtid=1035563

here is the proceedure listed under FAQ

Thanks Kevin, getting set to try this out on the weekend!

 

[LubeDude]

Re: 1985 Mariner 150hp Running, but seems very tired

I didn`t check this particular link out as to which one it is, but do the small tank decarb procedure, also spray some into the sparkplug holes too. I prefure to let things set overnight if I can. It will likely add new life to your engine.