04 Yamaha F150 corrosion

[Bdsp1234]

I’m looking at a 258 with twin 04 F150’s. I’m hearing conflicting reports regarding the exhaust corrosion. Some say only on the F225’s, and some say all Yamaha 4 strokes between 2000 and 2006. Motors run great, but have not had the exhaust replaced.

Love to hear your opinions

 

[seasick]

I am not aware of widespread corrosion issues with 150s but that doesn't mean it hasn't happened. Have the motors inspected and scoped if you are leaning towards the purchase.
A surveyor told me years back during the height of the 250 issues that he had seen corrosion on many Yamaha models and in his opinion, it was only a question of time.
It is hard to explain how a boat with the original twin motors ends up with fatal corrosion on one motor and nothing on the other. It is unknown to me if the cause was an alloy change or some other manufacturing defect and more importantly when it started and when if ever, it ended.
I have many fewer concerns with 150s, especially later year models.

 

[Fishtales]

Same here, but I know it has happened. You can have the engines scoped if they drop the lower units. A scope camera is inserted and the exhaust walls can be inspected. If they are shiny, the coating is compromised and it is only a matter of time before you have issues.

 

[Coach1575]

When I was looking for a Gulfstream, I was ready to pull the trigger on a 04 with twin 150's. Everyone was saying there were no issues with the 150's. Just to be safe, I had both engines scoped. One engine was fine other engine had corrosion issues. Moral of the story, pay to have them scoped.

 

[Ky Grady]

I agree with the others. There were issues with some of the 150's of that era, more so the 225's and some 250's. Definitely have the lowers dropped and scope them both.

 

[seasick]

Good to know about the 150 experiences.

 

[Fishtales]

I had a guy on the dock that had the issue with a 150 and a friend of the 200 4S. I think it was a coating composition issue that could have affected several motors. My dealer indicated Yamaha had a heat map (number of issues per location) and the issue was far more prevalent in the warmer water. I don't know if this was normalized for population as I would guess there are more boats in warmer climates. That being said, people use the data to their advantage and the message was "this is a warm water problem", we'll I scoped mine every year here in the NE and the problem eventually came.
I could have gotten away with more years (we guessed 3-5) but once I saw a lot of coating compromise, we did them proactively. Unfortunately, we will never know the real story.

 

[JeffPicc]

I had 2005 F150 and it suffered total corrosion failure this summer at 1400 hrs. terrible

 

[Punch53]

You also have the balancer gears self-destructing on the 150's. Probably more common than corrosion.

 

[Fishtales]

Too bad Yamaha didn't stand behind their products better. If there were more alternatives out there they may have been held accountable by the buying public. Seems like they can get away with just about anything right now.

 

[Andrew93]

We just bought a 1997 Islander with 2007 F150's. We looked at the whole package with rose colored glasses due to the price we pre negotiated. Motors had 560 hours on them. When we took the boat out it wasn't hitting top RPMs, but I blamed the props. When winterizing I dropped the lower unit to store inside and noticed a lot of pitting and evidence of an exhaust leak. Both motors had major corrosion to the block and mid sections. Corrosion int he block actually hate holes int he cooling jackets. Repair estimate was between 12-15k for both with remans. I figured $9k in parts, I was a little nervous to tackle this myself with that much expense in parts.

We ended up selling the motors for parts/repair and bought used HPDI's. The photos are of the bottom of the powerhead. The threads you can see are actually head bolts being exposed from the corrosion. We lost sleep over this whole ordeal but I think we found some good motors for a fair price. They are hanging and rigged now, but I need to button them up some in the spring.

 

[Punch53]

The small block HPDI has a proven track record of reliability and performance.

 

[Hookup1]

I replaced the balancers on my F150's a few years ago. Yamaha had problems with the gear drive was breaking down, clogging oil passages and blowing motor up. Mine were fine (no breakdown) but I had them changed anyway.

What did they attribute the corrosion's problems to?

 

[Andrew93]

The small block HPDI has a proven track record of reliability and performance.

Thats what I read and am hoping, have have had a lot of OX66's, these will be my first HPDI's. Motors are 2003's with 280hrs on them. I know low hours are sometimes worse than high. Sold the F150's for $3k and bought the HDPI's for $6500 with rigging. HPDI owner was completely refitting boat and was repowering while he was at it. This boat was supposed to be a "stop gap" from our 272 until the kids are older and then look into a newer 282 or Marlin. If I like these motors I might try and find a 282 with twin 200 HPDI's unless I really enjoy the better economy of the Islander over the beam of the boat.

I was told by a few people the corrosion is from the ethanol fuel residual in the exhaust gases. It reacts with the aluminum and eats it away. The reason 2 strokes were not effected the same way was due to the oil in the exhaust leaving a protective layer over the metal. Take it for what its worth but heard that from 2 different people. Also I found a white paper research document on how ethanol increases its corrosive properties the warmer it gets, kinda makes the exhaust ports a prime spot for this to happen to.

 

[seasick]

I never heard that and it doesn't explain the cause for folks who had twin motors, one corroded and the other fine.

 

[Andrew93]

I never heard that and it doesn't explain the cause for folks who had twin motors, one corroded and the other fine.

This link is one of the research papers I found when looking into this a few months back, I mainly read the abstract and conclusions and did not dive too deep into the paper itself. I agree it doesn't make sense on why one motor would be effected and another not with twins. Mine were very uniform in corrosion and it defiantly makes you think.

Definitely something to think about but I agree that this is not a sure thing

https://www.diva-portal.org/smash/get/diva2:720728/FULLTEXT01.pdf

https://www.process-design-center.com/shared/hydrous-ethanol/Corrosion,%20Polymers%20&%20Elastomers/IAV%20-%20Article%20Corrosion%20behaviour%20of%20Aluminium%20Alloys%20in%20Ethanol%20Fuels.pdf

 

[seasick]

I congratulate you on your document research. I read the first 45 or so pages of the first doc and my head is spinning. I probably understood about 10% of the material. It was like being in chemistry class in college in the 70s! I probably would have understood it better back then.
There were a few items that stuck out but it's all too complicated for my aging grey matter.
I saved the paper for future punishment
Thanks.

 

[seasick]

OK, ne thing I am not sure about. I have heard the Yamaha problem referred to as the dry exhaust corrosion issue. Is the flow in the exhaust stack actually dry? Cooling water gets mixed with exhaust at some point but where? I ask because one thing pointed out in the paper is that some of the aluminum corrosion by ethanol processes do not occur when water is present.
When I was reading the paper, I asked myself why aluminum carburetors are corroding away since ethanol was introduced.

 

[Andrew93]

From what I understand the exhaust passage is dry, water is introduced lower in the mid section. When I had my powerhead off one motor and scoped the other my worst corrosion was where there would only be combustion gases.

The second picture I posted is looking up the powerhead from the bottom and the third the exhaust guide that the powerhead bolts onto. I think the water from the cooling system is introduced in the exhaust guide or somewhere below this point.

 

[fishon]

From what I understand the exhaust passage is dry, water is introduced lower in the mid section. When I had my powerhead off one motor and scoped the other my worst corrosion was where there would only be combustion gases.

The second picture I posted is looking up the powerhead from the bottom and the third the exhaust guide that the powerhead bolts onto. I think the water from the cooling system is introduced in the exhaust guide or somewhere below this point.

Be sure to check behind the thermostat in the cooling water passage way on all Yamaha outboards especially the F-150’s and F-225’s were I have experienced severe corrosion due to dissimilar metals from the thermostat and cast aluminum water way sitting in salt water. Not a warm water thing , this is in so cal and both motors flushed and maintained religiously. Yamaha calls it lack of proper maintenance, “bullshit”. Just be sure to check behind the thermostat.