issues with older Yamahas??

[fastkenny]

i'm looking at buying a boat with '88 Yamaha 150's counter rotating. What are the most common problems with these? I know they're not new, but I'm hoping to get a few years out of them. The shift rods and fuel pumps have been replaced in both. What are the other big items to go? Other than the basics, what should I be on the lookout for? Thanks!!

 

[Capt. Stabbin]

Re: issues with older Yamahas??

I have a 1988 115 and it runs very strong. The thing that I would be concerned about would be with cracks in the foot behind the prop(s). I had 1 crack welded successfully, but recently had another on the opposite side appear. I guess Yamaha has saltwater corrosion issues with their older motors. Other than that, I love the motor.

 

[seahorse5]

Re: issues with older Yamahas??

If those are saltwater motors be aware that there were a lot of corrosion issues on the pre-1994 models.<br /><br />Also check for wrist pin bore wear which can feel like a loose rod bearing. Overpropping causes the wrist pins to "hammer" in the piston and wear the holes egg-shaped.<br /><br />Have a QUALIFIED tech check them out completely before purchase.

 

[BRIAN03]

Re: issues with older Yamahas??

The key to any engine is how its been cared for. If the engine was taken care of. 1. Run good two stroke oil. I like Yamaha oil only in a Yamaha. 2. Ring free run in the fuel. 3. That the engine has annual service by someone who know the product. My rule is the v-6 yamaha is good for 1000 to 1200 hours befor a major rebuild. I know the engine will run alot longer. But after so many hours the engine is down on power idles poor and has the chance of coming apart. The number one inherent problem with older v-6 Yamahas is the bottom bearing on the crankshaft. Its a Koyo bearing with a plastic cage and the plastic cage comes apart after 800 hours. These engines are do for rebuilds after 1000 plus hours.

 

[fastkenny]

Re: issues with older Yamahas??

Thanks for the replies:<br />How big a job is it to replace the bottom bearing on the crankshaft? These motors are reported to have around 500 hrs, but I don't think I can verify that

 

[fastkenny]

Re: issues with older Yamahas??

Additional question: The seller said that both shift rods were replaced. I asked if he had trouble getting the power heads off (what I thought was what made the job hard) - he said it was done by removing the lower unit. Is this possible?

 

[Capt Ken]

Re: issues with older Yamahas??

Gotta remove the powerhead. Have heard some mechanics say they removed the intakes and was able to force them in, but never saw it done that way.