What brand of outboard?

[snagged in outlet 3]

16 minutes ago, fishinwrench said:

The old school of thought with mechanical carbureted 2-strokes (and it has some merit) was that after 1/2 throttle the ignition was already fully advanced....so you might as well pour as much fuel/oil into the cylinders as possible.  That's where the old saying "2-strokes are designed to run full-throttle" came from.    Better to run 5500 RPM for 30 minutes, get there sooner and shut her down,.....than to run 4200 RPM for an hour and get there later. 

After tearing down, inspecting, and rebuilding a shitload of them.....I truly can't tell you which method is best for engine life. 

But one fact is constant.....a huge majority of catastrophic powerhead failures happen at mid-range throttle settings, even with today's computer controlled ignition and fuel metering systems.  The faster a piston moves/the less time is available for something to go wrong.

 

If weight weren't such a huge factor then 4S outboards that would last FOREVER could easily be designed.   But engine weight is a giant issue when your dealing with things that have to perform....and still float.   A 20hp push mower that cuts a 4' swath would be great....but you couldn't push it up a hill.

So full throttle on my Rude? 

For info purposes.  The 40 Merc jet that came on my boat smoked from day one.  My rude smokes less than that thing did.  It also fouled plugs continuously.  Half way through the warranty I bought the Rude with a boat show special 7 year warranty.  My buddy even commented that the Rude smokes less than the Merc did....  That is my experience.  Although limited.

[Devan S.]

12 minutes ago, fishinwrench said:

But one fact is constant.....a huge majority of catastrophic powerhead failures happen at mid-range throttle settings, even with today's computer controlled ignition and fuel metering systems.  

Out of curiosity, how do you know that for sure.

Do on-board computers record the RPM settings at that failure point?

Or is it just statistically the number of hours at certain RPM's?

Or is it the guy coming in a saying well.....I wasn't running it that hard when it blew. 

 

[Basfis]

1 hour ago, nomolites said:

I’ve had them all.  I think much has to do with setup and care.  Don’t under HP your rig, don’t set up to max out the RPMs, don’t run WFO(or idle for that matter) all the time-try to run mid-range, and take care of the equipment.  When I’ve done that, my stuff lasts…when not, it comes apart.

Mike

Power to spare is a big success factor for any engine. 

[fishinwrench]

14 minutes ago, Devan S. said:

Out of curiosity, how do you know that for sure.

Experience, and training. 

Plus the amount and depth of the dimples on a piston and cylinder head from shrapnel pinging around inside the cylinder, are a prime indicator of how "wound up" the motor was when all hell broke loose. 

15 minutes ago, Devan S. said:

Do on-board computers record the RPM settings at that failure point?

Yes.

16 minutes ago, Devan S. said:

Or is it the guy coming in a saying well.....I wasn't running it that hard when it blew.

The majority don't know the engine has powerhead damage until I tell them it does.   Occasionally I'll have one with a rod and chunk of piston blown out the side of the block.....When you see THAT you pretty much know. 😅

[fishinwrench]

This one here was wound up pretty tight..... wouldn't you say?

Not wide open though.  Likely in the 4800-5000 range.

[Devan S.]

hmmmm I guess when we talk powerhead failure that doesn't randomly happen solo on its own right....something else is generally the root cause?

 

[David Unnerstall]

3 hours ago, Dutch said:

I’m just curious.  I’ve seen a lot of posts about them and repairs on this site over the years.  I’m wondering what you guys run and your experience with them.  I personally am a Mercury fan.  I ran a 225 Optimax for 14 trouble free years.  I am now running a 250 Verado that is in its 6th year.  All it has had is oil, filter, and fuel changes along with lower unit service and this year spark plugs.  I have owned 4 Evinrudes and one Johnson.  I blew 3 of the Rudes and the Johnson.   

Chrysler.

[fishinwrench]

1 hour ago, Devan S. said:

hmmmm I guess when we talk powerhead failure that doesn't randomly happen solo on its own right....something else is generally the root cause?

 

Exactly.   9 times out of 10 it is something that is bolted to the powerhead that caused it to fail. 

 Simply installing a fresh powerhead without determining what caused the original one to fail....and rectifying THAT as well....is just ensuring that the replacement powerhead will also fail.  Dealerships with "certified techs" doing warranty work are FAMOUS for doing exactly that......"the powerhead failed, so replace the powerhead and ship it out".   

It just ain't that easy.   If you can't determine what caused the failure to occur then you need to thoroughly go through the entire fuel, lubrication, ignition, and cooling systems.   

The powerhead I showed pics of above went down because of excessive combustion chamber temperature, indicated by the melted top corner of the piston on the exhaust port side of the cylinder.  It wasn't a fault of the cooling system though.  It was caused from restricted fuel/oil because for some unknown reason Mercury designed the 2.5L injector's with SCREENS over the tip of the injectors.   WHY ?    If something is small enough to pass through the injectors....why not just let the motor chew it up and spit it out????   Noooo, we're gonna let that crap build up on the screens and potentially restrict the fuel and oil going into the cylinder.   A result of outsourcing....those injectors are built in Japan and sent to them that way.

Needless to say.....I pop those idiotic screens off with the edge of a putty knife, and pitch them in the trash.  And I've never (knock on wood) had a 2.5 repeat failure. 👍.  So until someone from Mercury explains what useful purpose those screens serve....in ENGLISH, NOT JAPANESE....they will continue to get thrown in the trash at Sims Marine in the United States.

[rps]

2 hours ago, fishinwrench said:

Exactly.   9 times out of 10 it is something that is bolted to the powerhead that caused it to fail. 

 Simply installing a fresh powerhead without determining what caused the original one to fail....and rectifying THAT as well....is just ensuring that the replacement powerhead will also fail.  Dealerships with "certified techs" doing warranty work are FAMOUS for doing exactly that......"the powerhead failed, so replace the powerhead and ship it out".   

It just ain't that easy.   If you can't determine what caused the failure to occur then you need to thoroughly go through the entire fuel, lubrication, ignition, and cooling systems.   

The powerhead I showed pics of above went down because of excessive combustion chamber temperature, indicated by the melted top corner of the piston on the exhaust port side of the cylinder.  It wasn't a fault of the cooling system though.  It was caused from restricted fuel/oil because for some unknown reason Mercury designed the 2.5L injector's with SCREENS over the tip of the injectors.   WHY ?    If something is small enough to pass through the injectors....why not just let the motor chew it up and spit it out????   Noooo, we're gonna let that crap build up on the screens and potentially restrict the fuel and oil going into the cylinder.   A result of outsourcing....those injectors are built in Japan and sent to them that way.

Needless to say.....I pop those idiotic screens off with the edge of a putty knife, and pitch them in the trash.  And I've never (knock on wood) had a 2.5 repeat failure. 👍.  So until someone from Mercury explains what useful purpose those screens serve....in ENGLISH, NOT JAPANESE....they will continue to get thrown in the trash at Sims Marine in the United States.

Probably everything that needs saying is above. My personal experience has been Evinrude. That is what I inherited from my father, and what I have had on every boat since, save one. I had a Mercury 2 stroke 25 on my Supreme. I have had Etechs on the last two boats, covering 15 years. Both have had WOT at 5800 +/- rpm. I mostly ran each at 5000 rpm. I had each serviced at manual recommended times (far less than the 4 stroke recommended every year). In fifteen years, the only problem I had was when Ulrich failed to complete connections after a service job. When I brought it back, they admitted their mistake and did not charge me. I was sad to see the announcement that the Evinrude brand was to be discontinued.

[fishinwrench]

44 minutes ago, rps said:

I was sad to see the announcement that the Evinrude brand was to be discontinued.

I was too.  And still am sad about it.  

Evinrude was the only company that built outboards for the primary purpose of freshwater use.    They honestly tried to build them to last.  And still, even though they have ceased production, are supplying parts for ALL those motors to this day.....and have vowed to continue doing so for as long as there is demand.

All other outboard manufacturers sell the huge majority of their units along the coasts (saltwater).  They know that no matter how well they design and build them.... they're only gonna live a rather short life due to saltwater corrosion.  So they have no desire to produce an outboard that will last multiple decades, and they certainly have no intention to keep supplying parts for them shortly after their warranty expires.       Basically spitting in the face of all their freshwater customers.....cuz to them the freshwater sales are such a small little piece of their overall pie.