Driveshaft won’t engage powerhead

[Masonmobilemarine]

Wonder if it’s a new gen thing, like the cars that fail just out of warranty now. Might see this becoming common as they start to slip out of warranty and fail.


hey mason was that one of the newer gen motors?

Here's another one 99.

This entire thread has been about a crankshaft stripping it's splines. Others said they had never seen it. Some asked particular questions about my motor.


I know already you don't like me, but you should read a little more before being rude...you won't look silly next time.

[TownsendsFJR1300]

Here's another one 99.

This entire thread has been about a crankshaft stripping it's splines. Others said they had never seen it. Some asked particular questions about my motor.

.

Not sure of the mix up, but the original thread was about the INTERNAL SPLINES "going away".

Your posting (pic's) of CRANKSHAFT BEARINGS, is completely different than the internal, MACHINED splines in the CRANKSHAFT.


Have you had an engine that the crankshaft SPLINES (THAT ENGAUGE the LU) stripped out?

[Masonmobilemarine]

Not sure of the mix up, but the original thread was about the INTERNAL SPLINES "going away".

Your posting (pic's) of CRANKSHAFT BEARINGS, is completely different than the internal, MACHINED splines in the CRANKSHAFT.


Have you had an engine that the crankshaft SPLINES (THAT ENGAUGE the LU) stripped out?

Towns....yes I have, I tore it down about a month or two ago. I posted recently after the OP said what his problem is...but stayed off the forum a few days.

I'll post pictures of the cranks later (don't have any right now).

I posted pictures of my block and thrust bearings to show the damage that could have led to the crank stripping, or just a completely separate issue. Was just bring food for thought with the pictures. ...aka, potential aftermath of a crank stripping .

[boscoe99]

What does it mean when some have not seen a certain type of damage or when some have seen a certain type of damage many times?

A Yamaha mechanic in Kansas could very well have never seen an F350 crank shaft failure.

A Yamaha mechanic in Miami could very well have never seen an SHO thrust bearing failure.

A Yamaha mechanic in Wisconsin could very well have never seen a 3.3 liter F225 with mid-section corrosion.

There may be 8 different failures that might cause a model to run ruff. Folks come along want to know what someone did to stop their model from running ruff. Could be two completely different failure modes.


Does it really matter who has seen, or not seen, what? If there is a problem, do proper trouble shooting, find and fix the problem. Don't rely on what someone else found to be the problem and cure for their particular motor. To do so will send one down the rabbit hole. Rodnut knows all about this.

[TownsendsFJR1300]

Rodnut posted he's NEVER seen splines stripped out.


I for one, am interested in how this failure occurred.. Which we may never know BUT it apparently DOES HAPPEN..

It's not sending anyone down a rabbit hole.

It was asked as an issue, etc, which no one else had ever posted about.. Mason apparently has...

[Masonmobilemarine]

Here is a couple pictures.

I have a 2005 F225 with a good crank...and the 2003 F225 crank that is stripped. Pretty sure they are the exact same crank.

As I said, splines on the lower unit drive shaft are perfect. No pic because the lowers are in garage corner and I rolled ankle tonight.

See the difference?

[zenoahphobic]

Here is a couple pictures.

I have a 2005 F225 with a good crank...and the 2003 F225 crank that is stripped. Pretty sure they are the exact same crank.

As I said, splines on the lower unit drive shaft are perfect. No pic because the lowers are in garage corner and I rolled ankle tonight.

See the difference?

You should have lit up the damaged splines a bit more, however you can see how the splines are being hammered away.

I guess initially the hardening broke down, now probably the "soft" metal is all that remains and wear will occur at an accelerated rate.

I think what happens the hardening surface layer actually cracks into small fragments that then get pulverised to powder. In this state the powder can rust very rapidly with little moisture needed. This failure process is more commonly seen in roller bearings under high load or inadequate preload say in wheel bearings where the play leads to this destructive hammering.

[TownsendsFJR1300]

Thanks for the pictures Mason... Wow....

Zeno's explanation makes sense.

I could see that happening on a higher HP/ torque engine, but the smaller engine less likely.. Obviously, nope...

[DennisG01]

Looking at those pictures - and just throwing out an observation. The buggerd crank splines show obvious rust/corrosion. IF that corrosion was a factor... the question is, which came first... did the buggered splines allow a larger gap for seawater/moisture to enter? Or, from lack of maintenance (pulling the lower to re-grease those splines), did the corrosion set in and weaken the splines?

[99yam40]

I agree that looks like rusted away splines

If you had posted those pics of spines earlier your post would never been questioned by me

[Masonmobilemarine]

I'm actually not so sure that's corrosion but just really dirty grease (probably from the splines shredding).

We definitely have very bad corrosion issues here at the gulf in Florida, but I think the light in the picture makes it look bad. I'll try to see if I can clean the grease and get a better picture.

Would make sense though, rust eat away the top hardened metal and then start slamming away at the softer metal.


Yam, I didn't have pics available at the time.

[ausnoelm]

While the rust theory sounds plausible, why doesn't it affect the driveshaft splines too? They are matched together, one wears/rusts so should the other, just to add, I have seen this before, and there was plenty of grease and no rust present.

[DennisG01]

While the rust theory sounds plausible, why doesn't it affect the driveshaft splines too? They are matched together, one wears/rusts so should the other, just to add, I have seen this before, and there was plenty of grease and no rust present.

Correct me if I'm wrong, but isn't the crank made from a different metal than the driveshaft?

I'll throw another Hail Mary out there... the crank could expand under heat at a different rate than the driveshaft, especially if it's a different metal. If it would expand, that could exacerbate the problem. It wouldn't be the ONLY reason, of course, but it could be a variable. Not sure if things get hot enough for that, though?

[zenoahphobic]

Correct me if I'm wrong, but isn't the crank made from a different metal than the driveshaft?

I'll throw another Hail Mary out there... the crank could expand under heat at a different rate than the driveshaft, especially if it's a different metal. If it would expand, that could exacerbate the problem. It wouldn't be the ONLY reason, of course, but it could be a variable. Not sure if things get hot enough for that, though?

Yes plausible, and also the energy pulses come from the engine and not the shaft, you get this "master/slave" situation something catastrophically has to give.

I can think of an illustration of this- a bit far out you might think. A man and a piece of wood. You can hit and hurt that man with the piece wood, but that man can also hit that piece of wood and break it (think Karate). Same force but applied differently!
Or a simpler example, a person deliberately hitting your forehead with his forehead and hurts you and not himself.

[ausnoelm]

I do believe the drive shaft splines are "case hardened" meaning just the end, and the outer surface of the metal is hardened, the crank however might be a very different story, it is cast, machined then hardened, and I think (I have never seen a crank made) only the bearing surface areas are hardened? has anyone ever seen a mass produced crank made? I don't know, but maybe the spline end is "soft" or perhaps the entire crank is hardened as a unit?