Checking out a 115 Yammy 4 stroke!!!

[LindenLongRods]

Thursday I'm gonna check out a boat, The motor is a 115 Yamaha 4 stroke. Do I do a compression check like I would on a 2 stroke? What are the steps for a compression check? What should it read? I will check the lower for milky white. Is there anything else I should be aware of? The boat is a 2000 so I'm guessing the engine is also. Any help will be greatly appreciated.

 

[CATransplant]

Re: Checking out a 115 Yammy 4 stroke!!!

Yup, same compression test procedure. Checking the lower unit oil is a great idea, too. Best idea of all, though, is an on-the-water test run. If that's possible, I'd sure do it, especially for the amount of money you're likely to be spending.

 

[tommays]

Re: Checking out a 115 Yammy 4 stroke!!!

Well

If you were in the Yamaha forum Rodbolt would say go with a leakdown test as it would show the condition of the valves as well as rings

 

[andymach23]

Re: Checking out a 115 Yammy 4 stroke!!!

It would be good to get a look at the crank case oil if possible after a good run.

I bought a used Yamaha F80 on my boat and when I changed the oil a couple of months down the line before launching, it was pure white due to water ingress.

The pre-purchase surveyor had run the engine with water contaminated fuel. The motor then went to the Yamaha shop who cleared out the carbs etc. I The Jackass didn't change the oil though.

I changed the oil a further 4 times before launching after running for an hour on the hose. The oil was still a bit cloudy after that. I've launched now and will do a change soon after about 10 hours running. Hopefully it will be ok.

If I had of thought I should have at least had a look at the oil on the dipstick and maybe smeared it on something dark.

Someone sneaky could put fresh oil in I suppose, to hide something.

A warranty on the motor would be ideal to cover yourself.