Motor rebuild Questions

[nra4life]

Im looking to buy my first bass boat(used), and have a few questions.

1.  How do you know when to rebuild a motor?

2. Do you only rebuild bigger outboards?

im sure ill have more questions later

thank you

[cart7t]

1.  How do you know when to rebuild a motor?

If you're running along and the motor goes BANG, clankity, clank, clank you might need to rebuild the motor.

Seriously, before you buy, take the boat to a qualified marine mechanic and let him do a thorough test on the motor to let you know.

2. Do you only rebuild bigger outboards?

It's one of those cost exceeds value kinda deals. Unless you can do it yourself the cost of parts and especially labor makes only the larger outboards economical to rebuild and even those it really depends on how old the motor is.

[nra4life]

thanks for the reply, im looking for a boat that is maybe 10 years old or so, I just want to know if im gonna have to worry about getting it rebuilt soon after i buy it.

How much does it cost to get a 90 or 115 hp motor rebuilt?

[Way2slow]

When to rebuild? As cart7 says, when it goes bang is a pretty good time.  When the compression is too far off (more than 10% difference between cylinders) or too low on all cylinders.  When it's knocking or sounds like somebody rattleing a can of rocks inside.

Most motors ten years old or older will cost more to have rebuilt than the motors worth.  If you can do the work yourself is about the only time it's worth rebuilding.  That applies to most anysize motor. Just to bore and replace pistons and rings you can be  looking at close to $200 per cylinder, then you have labor charges and other parts involved.

This is why it's always better to have a boat/motor checked out by a competent mechanic that know outboard motors and boats.

By the way, age doesn't have a lot to do with what kind of shape a motor is in.  The type oil, hours, upkeep and preventive maintenance has a whole lot more to do with it than age.

[RobDar]

When to rebuild? As cart7 says, when it goes bang is a pretty good time. When the compression is too far off (more than 10% difference between cylinders) or too low on all cylinders. When it's knocking or sounds like somebody rattleing a can of rocks inside.

yep yep yep!!!

have it checked head to toe....

and have the compression checked...AGAINST THE MANUAL FOR THAT MOTOR!!!!

why is that in caps??? here is why...

There are a handful of motors out there that are funny...

I was told my powerhead needed to be rebuilt by 4 different mechanics. I have half as much compression on my center cylinder as I did on my outer two...so there was a problem...right?

Well after 4 estimates for some simple work ( not the powerhead) that gave me chest pains, I got hooked up with an old man who fishes our tournament circut who was a mechanic "when the other guys were just a glimmer in their mama's eye" as it were. I told him about the compression. He looked at me confused and said...

"yeah...so what."

Apparently there were two versions of the 60 Horse johnson of my era ( the 1980's). One was a suped up 50 horse and the other was a "delimitied" or cut back 70 horse.  The limited 70 horse...which is immediately recognizable by the oversized lower unit...had the center cylinder compression limited to reduce its horse power.

I did not believe him.

So I called Johnson.

He was right.

The other thing he fixed was my oil alarm. The other mechanics wanted between 500 and 700 hundred to change my VRO...yadda yadda yadda...

turns out it was the float in my oil tank. Over time the float becomes satuarated with oil and gets sticky. He put a new float in it for $18 bucks and away I went...

so my $500 dollar VRO fix...and $2000 dollar powerhead rebuild...cost me a total of $78 bucks.

and BOTH these issues with my boat are listed in the troubleshooting guide of the manual for my boat. So ask to see the manual to reference what the compression etc etc really ought to be.

do not simple trust your mechanic to be honest with you or to know every motor ever built.

[gg4709]

It is possible to try and do it yourself, the only hard part is having the tools to do it. Anything like replacing parts can be done in your garage with a socket set, screw drivers, and channel locks. Rather than going to a marine shop that charges 50% more, go to O'Reillys auto part store. They should have a huge thick Sierras marine book full of just about any part that goes in your engine. For machining work that will more than likely have to be done by a certified outboard mechanic.

One more important thing to remember is KNOW YOUR ENGINE.  It will save you a lot of time and money if you know what size parts and what kind of parts are made for your particular year model engine.  Outboard parts will vary from HP to HP and year model to year model.