Connecting Rods question

[Searun1]

Need some advice guys...<br /><br />The mechanic at my local shop says that my connecting rods are loose in my 1980 70 HP Johnson seahorse.<br /><br />He says that the engine may run for another hour, another week, or another year but sooner or later its toast.<br /><br />The engine runs fine but I guess it has alot of hours on it according to them.<br /><br />Is this something that I can fix on my own? I would like to become a better outboard mechanic and this might be a good project.<br /><br />They have told me the best thing to do would be to get a new powerhead. I would rather put the money towards a new yamaha.<br /><br />Any advice? Is this too complicated of a procedure for a relative novice?<br /><br />Searun1

 

[stairliftoheaven]

Re: Connecting Rods question

You will need a manual to start with!

 

[alcan]

Re: Connecting Rods question

Hi Searun<br />At this point it really doesn't matter how complicated the job is,you want a new motor. Anything elese would just be a pain.

 

[Spidybot]

Re: Connecting Rods question

Yeah. On top of it, a new(er) motor will perform better, use less fuel, meet environmental requirements and be more reliable.<br /><br />Even a chance to get more/less hp or switch technology (2-stroke/4-stroke/3rd generation 2-stroke: TLDi/Ficht etc.) if you like.<br /><br />I'd shop around and see what's available.

 

[BoatBuoy]

Re: Connecting Rods question

Searun1, If the con rods are loose, it requires a major tear-down to fix and maybe some expensive parts, like a new crank. In any case, when an engine is torn down for a certain reason, it only makes sense to also perform other repairs at the same time. For example, I would want to at least hone the cylinders or have a machine shop true them up and put new rings in. Other new bearings might be in order. This can be a costly job and not one for the timid.

 

[Dhadley]

Re: Connecting Rods question

He says your rods are loose. From what?<br /><br />What is it that the motor does or doesnt do that you want to change? What led him to this conclusion?

 

[rodbolt]

Re: Connecting Rods question

dude<br /> a loose rod bearing is rare. usually by the time you find them loose, its cause your looking at it through the hole in the block. maybe a wristpin is getting loose or something is badly rusted. why do you suspect its loose and how was that determination made?<br /> good luck and keep posting

 

[seahorse5]

Re: Connecting Rods question

Rodbolt is right. It is probably a worn wrist pin hole in the piston and that makes "slop" in the rod and wrist pin assembly. It is common in older motors that are overpropped and are "lugging". Some will run for years and years that way, and others may break a piston. It's a crap shoot. Yamaha had the problem with their V4 years back, also.

 

[Searun1]

Re: Connecting Rods question

The mechanic said he could hear it as he began his tune up. I cant hear anything different and the engine sounds fine to me but I am not a pro. I posted earlier that the engine was not running at high enough RPM's and I believe the prop on the engine is too much which makes perfect sense with what seahorse says.<br /><br />I will switch props and cross my fingers and see how long she makes it. I am shopping for a new motor as well. Thanks.<br /><br />Searun1

 

[stairliftoheaven]

Re: Connecting Rods question

propping down is the first step before you take the plunge and buy an mew motor, see how it goes, your johnson could go on for years....

 

[Dhadley]

Re: Connecting Rods question

Before you spend money on a prop, work the set up to maxamize what you have.

 

[Searun1]

Re: Connecting Rods question

DHadley, what do you mean by "work the setup?" I am willing to do quite a bit as I need to save a little more before I can afford a new engine.<br /><br />Searun1

 

[Dhadley]

Re: Connecting Rods question

I posted earlier that the engine was not running at high enough RPM's and I believe the prop on the engine is too much which makes perfect sense with what seahorse says.

If you are looking for more top rpm's you can try raising the motor to increase your X dimension. That will reduce drag and improve overall performance.<br /><br />How far you can raise the motor depends on the style, technology and condition of your current prop.