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  Topic Review (Newest First)
1 Week Ago 02:14 PM
ccriders
Re: 1989 Hunter 40 - A million questions.

Quote:
Originally Posted by MastUndSchotbruch View Post
Yes, all good reasons that could cause it. However, I believe that in my case, it is nothing more than a bit of play in the control cable. As you probably know, the Atomic 4 needs a lot of force for the reversing gear and, as a consequence, a much sturdier cable than diesels. I have a pretty old cable with a bit of play in it. If I put the lever just so, the shaft disengages and stops turning. If not, the shaft turns "without gusto" (I like your term!), maybe a rotation per second. I have never tried it (and don't intend to do so) but it seems there is so little force on it you could stop it by hand. I think the reason is a tiny bit of friction somewhere because the cable/shifting lever is not in the perfect position and the disks are just rubbing on each other.

I am pretty sure this is harmless. Am I wrong?
I don't know if it is harmless or not. Investigating the same situation on my boat I found that the shift cable housing had slipped in its clamp just before the boats shift lever, not the engines, when I reseated it, the slow rotation went away.
1 Week Ago 02:15 AM
smackdaddy
Re: 1989 Hunter 40 - A million questions.

Andre - in this case what I understand from the notes is that the flywheel-side thrust was asymmetrically worn down - significantly. And it was the main bearing (at the flywheel-side of the engine) that failed as you can see in the video. There certainly appeared to be "uneven" force at that thrust.

Again, I'm not a pro and this is just my lay understanding. So forgive the terminology slaughter. But the measurements indicated atypical wear.
1 Week Ago 10:34 PM
MastUndSchotbruch
Re: 1989 Hunter 40 - A million questions.

Quote:
Originally Posted by Capt Len View Post
M&S If a disc type tranie suffers an over heat and warps a disc even a little it will never quite disengage and the shaft will slowly turn without gusto. in neutral . Other causes like thick oil Or water in oil or crud from wear or too quick change while reved can do it too.It's no biggie until it manifests itself in failure to fully dis/engage or always hot .Just my opinion as a bystander
Yes, all good reasons that could cause it. However, I believe that in my case, it is nothing more than a bit of play in the control cable. As you probably know, the Atomic 4 needs a lot of force for the reversing gear and, as a consequence, a much sturdier cable than diesels. I have a pretty old cable with a bit of play in it. If I put the lever just so, the shaft disengages and stops turning. If not, the shaft turns "without gusto" (I like your term!), maybe a rotation per second. I have never tried it (and don't intend to do so) but it seems there is so little force on it you could stop it by hand. I think the reason is a tiny bit of friction somewhere because the cable/shifting lever is not in the perfect position and the disks are just rubbing on each other.

I am pretty sure this is harmless. Am I wrong?
1 Week Ago 04:57 PM
Omatako
Re: 1989 Hunter 40 - A million questions.

I will be very interested in the professional diagnosis of this failure. My understanding of marine drive units is that they contain a robust thrust device against which the prop shaft pushes. The thrust from the drive should never reach the back of the crankshaft.

This engine failure leaves me with sense of disbelief and for me, challenges the seemingly unassailable reputation for quality the Yanmar engines enjoy. Here's why.

I have the exact same engine in my boat. Some years ago it suffered an oil leak so bad that it pumped the entire contents of the sump into the bilge and set off the alarm buzzer within about four minutes of a cold start.

The cause? The thrust plate at the front of the camshaft had worn away to the extent that the camshaft was able to move backwards far enough to rub against the plug in the back of the block (that seals the camshaft gallery). With the constant contact, the end of the camshaft welded itself to the plug and spun it in its aperture, destroying the perfect finish needed for the plug to create a leak-proof seal. Effectively the engine block was scrap.

I'm not going to go into the extent of the repair I had to do to save the engine but it worked and the engine has done another 1000-odd hours since then. But I'm left wondering about the quality of the thrust components in Yanmar engines. This failure does nothing to ease my concerns.

Whilst I agree that the misalignment shown in Smack's video is pretty dismal and the engineer's acceptance of a shaft turning while in neutral is surprising, I am skeptical of such misalignment causing an engine failure like this. I'm more of the opinion that this is generic Yanmar.

Smack, please post information on the final assessment of the failure - I would be keen to read it. It would seem to be a great coincidence for the engine to fail at the same time as the engine re-alignment and not be connected but my skepticism persists.

As M&S said, I'm OK to be educated . . . .
1 Week Ago 12:58 AM
Capt Len
Re: 1989 Hunter 40 - A million questions.

M&S If a disc type tranie suffers an over heat and warps a disc even a little it will never quite disengage and the shaft will slowly turn without gusto. in neutral . Other causes like thick oil Or water in oil or crud from wear or too quick change while reved can do it too.It's no biggie until it manifests itself in failure to fully dis/engage or always hot .Just my opinion as a bystander
1 Week Ago 12:25 AM
RobGallagher
Re: 1989 Hunter 40 - A million questions.

Good heavens, the shaft still spun in neutral and they said it was fine? How did they expect you to stop the boat?

Holy shite, look at that engine alignment with the stern tube. I wonder if the shaft could have been spun by hand in neutral at all?

I feel for Ya! I'd be livid.

When the flags go up...listen to them (next time, lesson learned). I hope you have some luck getting things sorted out. I'd get more 'second opinions' and take them to small claims court or at least get a lawyer to start sending letters.

Good luck!
1 Week Ago 09:57 PM
Capt Len
Re: 1989 Hunter 40 - A million questions.

Well, experts are entitled to their opinions too. gotta be careful with credentials . Utube is full of examples. (by bad teachers) And marine shops too. I've been butt up in a bilge since I was old enough to hand my Dad a wrench and gotta say I like Overboreds post..Seen shafts spring inches after aligned by experts ,But what do I know about your situation! by the way, I start with fitting couple to shaft and checking wobble at the taper , face the two halves of coupling .All this on a big lathe .IN the bilge the shaft is supported in position and tranny flange brought to it. Proper alignment can now start. My dial indicator doesn;t see much action anymore and I'd pass it to a worthy hand.
1 Week Ago 01:20 PM
smackdaddy
Re: 1989 Hunter 40 - A million questions.

Quote:
Originally Posted by overbored View Post
Smack,
Glade to see you are moving ahead with a new engine. good video so now I have been able to catch up on what happened. I am a little concerned when I here a mechanic says the motor alignment to the shaft caused an engine crankshaft main and thrust bearing to wear out. just a 1 in a 100 trillion chance. the trans output shaft in not coupled to the crank shaft directly. The trans has two shafts an input and output shaft. they are both running in tapered roller bearings which takes any axial and radial load on the output shaft. the shaft would have to pushed through the trans case to come in contact with the clutch and crankshaft assembly. If I was you I would read up on how an engine/ trans is aligned to a prop shaft with feeler gauges so you can assist the mechanic and make sure he understands the procedure also. it is also hard to do while the boat is in the water because you need to put in the temporary shaft centering wedges between the shaft and the stern tube. the shaft needs to be in the center of the tube and aligned with the strut before you can start to align the engine to the shaft. how did they machine the shaft flange on the new flange that they installed? my guess is they did not. the shaft needs the new flange installed on the prop shaft and the flange face machined to be true to the shaft. if this is not done right you will never be able to properly align the engine and the shaft will not run true and vibrate. the story about the engine mounts will break in. well just not true. as you know now. if they need to break in then why do the engines in brand new boats run so smooth. Good luck with the new engine. remember you always have those auxiliary white cloth looking things in case you ever have engine trouble.


Inboard Engine Alignment - Frequently Asked Questions - eBasicPower.com
Well, I'm obviously not qualified to get into the weeds on all this - and I certainly don't have the knowledge or ability to "assist the mechanic" in this area. But I do know this - the mechanic is definitely qualified in marine diesel engines (that's what he does - and was highly recommended). He did a very thorough inspection of the engine before it was pulled from the boat, during its removal, and after it was pulled from the boat, and we then submitted his findings (backed by plenty of evidence) to a Yanmar specialist who agreed with his diagnosis. So, I've got two pros agreeing on what happened based on first-hand knowledge of this engine and this situation.

Furthermore, in additional inspections of the engine and drive (tearing them down further by yet another party with their own Yanmar specialist) there has been absolutely no other indication of what else would have caused this problem (no overheating, good fluids, no water in the oil, no leaks, no blockages, no other breakages, etc.)

So, I don't know where your odds numbers come from - but I've been shown each step of the way why the diagnosis was made by these two pros. And it certainly adds up from everything I can see.

So I'll have to leave it there.

PS - Those sails saved our butts when the engine died in the middle of a very busy ship channel. I love those white cloth things.
1 Week Ago 07:46 AM
MastUndSchotbruch
Re: 1989 Hunter 40 - A million questions.

Quote:
Originally Posted by Capt Len View Post
Wrong oil (too viscous ) can cause that. Maybe the detent can be adjusted.
The oil is the right one (SAE 30) but you may be right about the detent. But it seems a really insignificant problem so I never bothered. The shaft is moving so slowly (maybe a rotation per second) that I don't think it does anything.
1 Week Ago 03:09 AM
overbored
Re: 1989 Hunter 40 - A million questions.

Smack,
Glade to see you are moving ahead with a new engine. good video so now I have been able to catch up on what happened. I am a little concerned when I here a mechanic says the motor alignment to the shaft caused an engine crankshaft main and thrust bearing to wear out. just a 1 in a 100 trillion chance. the trans output shaft in not coupled to the crank shaft directly. The trans has two shafts an input and output shaft. they are both running in tapered roller bearings which takes any axial and radial load on the output shaft. the shaft would have to pushed through the trans case to come in contact with the clutch and crankshaft assembly. If I was you I would read up on how an engine/ trans is aligned to a prop shaft with feeler gauges so you can assist the mechanic and make sure he understands the procedure also. it is also hard to do while the boat is in the water because you need to put in the temporary shaft centering wedges between the shaft and the stern tube. the shaft needs to be in the center of the tube and aligned with the strut before you can start to align the engine to the shaft. how did they machine the shaft flange on the new flange that they installed? my guess is they did not. the shaft needs the new flange installed on the prop shaft and the flange face machined to be true to the shaft. if this is not done right you will never be able to properly align the engine and the shaft will not run true and vibrate. the story about the engine mounts will break in. well just not true. as you know now. if they need to break in then why do the engines in brand new boats run so smooth. Good luck with the new engine. remember you always have those auxiliary white cloth looking things in case you ever have engine trouble.


Inboard Engine Alignment - Frequently Asked Questions - eBasicPower.com
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