Perkins 4 108- Sheered Engine Mount Bracket

[libbymr]

A couple weeks ago coming down from Seattle we wrapped pot around the prop shaft at night, didn't quite seize the engine but it got close. We were able to spin off the line but the damage was done,

It appears to have messed of the PSS seal( lots of leaking now), bent the prop shaft and sheered off the brackets for the engine mount, throwing everyhing out of alignment. The latest discovery was the engine mount being sheered off from the engine.

Has anyone seen anything like this before? Has anyone ever had to replace the brackets AND the mounts?

Vessel was supposed to depart to Mexico on May 1 but with this I don't think that's happening.

Photo

[tkeithlu]

Wow! That was some line you (literally) tangled with. I'm sorry, and no, I've never heard of someone experiencing that much damage for eating an anchored line.

You're right. You're not going anywhere that requires the engine any time soon.

The first steps will be to haul the boat, disassemble, and order new parts. I'm hoping that the engine mount bracket is a separate part and available. The shaft may or may not be eligible for straigthening, with "not" being the best bet. I'm concerned about the shaft log - that shaft really whipped around down there, and may have damaged it in the process. Do measure it carefully to see that it is straight and centered, without cracks. You can count on all four engine mounts being torn. With a little luck the shaft seal will be repairable - its leaking may just be the product of the bent shaft.

Best of luck with it. Your only consolation is having a story to tell.

[kapnd]

Be sure that your mount beds are correct before installing the new engine mounts.
By this i mean that the beds need to be in plane with the crankshaft, and perpendicular to the engines vertical axis.
I see far too many engine mounts flat mounted while the engine is tilted, so that the rubber mounts are deflected from the getgo, and I suspect this may have been the reason for such extensive damage to your rig.
Take the opportunity to re-engineer the whole drivetrain, and it should outlast you!
A Drivesaver might have saved you some damage.
Wouldn’t it be great if a reputable manufacturer came up with a torque converter for marine use that could prevent this type of damage, and smoothly transmit power through shifts?

[stormalong]

From the picture it looks like the bell housing that is broken, not the engine. If so that is actually good news - financially. If that is so you should be able to replace it without pulling the engine.

If those mounts are over 10 years old you may as well replace them while the work is being done.

A bent, misaligned shaft would be enough to cause the PSS to leak without the PSS being damaged.

[Tia Bu]

This kind of damage happens all the time with power boats. A good yard can fix it without too much drama. I disagree that your trip to Mexico should be delayed that much. With some luck, maybe a week in the yard? Get a good boat mechanic who can help you get it all lined back up. You can do it yourself, but good boat mechanics do this sort of thing a lot. Find a good machine shop, too. Don't wig out.

Happy travels!

[ttex]

Man! That sounds pretty bad. I can't even imagine. I had no idea a crab pot line could do that much damage. Eye opening.

[mlydon]

I had a similar thing happen wrapping a line the shaft on a cape dory - the line built up between the prop and the keel and yanked the whole motor backwards, shearing all 4 rubber mounts.

No a great picture, but as others stated, it looks like the cracked mount is on bell-housing. I’m not overly familiar with that particular rig, but the mount is either part of a casting, or bolts onto the trans. If it’s a bolt-on, easy to replace...if it’s the bell housing, should be able to sourceanother one.

Update - I just saw a picture of one for sale - looks like the mount bolts on those 3 holes on either side....

Take a look at yours, but maybe easy fix. The shaft and all are a bummer.

Matt

[Boatyarddog]

Originally Posted by ttex

Man! That sounds pretty bad. I can't even imagine. I had no idea a crab pot line could do that much damage. Eye opening.

It's a great example why the packing glands are appropriate.
A bit more robust than the bellows on the "drip less".
Boatyarddog

[rbk]

Pretty sure all Perkins 4108 engine mounts are all bolt on. Take that one off and get a new one welded up. Even see if there’s a matching one you could use as a template. New mounts, new shaft, PSS is probably ok as well. If this was a packing gland then damage would have been worse and the broken part may have been your crank shaft instead of a cheap bracket. Unless there’s damage to the shaft log this shouldn’t take more than a couple of weeks (even doing the work yourself) and a haul out, not even real expensive either. Again, if not shaft log damage you have an ‘almost’ best case scenario and be happy you’re not having to engine shop or full bottom end rebuild. I wouldn’t cancel that trip just yet. Please follow up

[Boatyarddog]

Originally Posted by rbk

Pretty sure all Perkins 4108 engine mounts are all bolt on. Take that one off and get a new one welded up. Even see if there’s a matching one you could use as a template. New mounts, new shaft, PSS is probably ok as well. If this was a packing gland then damage would have been worse and the broken part may have been your crank shaft instead of a cheap bracket. Unless there’s damage to the shaft log this shouldn’t take more than a couple of weeks (even doing the work yourself) and a haul out, not even real expensive either. Again, if not shaft log damage you have an ‘almost’ best case scenario and be happy you’re not having to engine shop or full bottom end rebuild. I wouldn’t cancel that trip just yet. Please follow up

Doubtful of that accuracy.
But that's a continuing thread,elsewhere.
Boatyarddog

[rbk]

Originally Posted by Boatyarddog

Doubtful of that accuracy.
But that's a continuing thread, elsewhere.
Boatyarddog

Have you ever even seen a 4108?
OP I would give Trans Atlantic Diesel a call. They may have some kicking around off a parts engine. A quick search I found some front brackets, no rears; but if you go to TAD website:
https://www.tadiesels.com/perkins-4108.html
You can clearly see the rear bell housing bolt on mounting bracket. Some rear mounts are actually on the transmission. If the mounts were cast with the block you'd most likely be missing a chunk of engine block. If the packing gland is cast into the hull/stern tube as many space limited shaft seals are, with little to no flexible hose then you'd have some serious repairs.

[Boatyarddog]

Originally Posted by rbk

Have you ever even seen a 4108?
OP I would give Trans Atlantic Diesel a call. They may have some kicking around off a parts engine. A quick search I found some front brackets, no rears; but if you go to TAD website:
https://www.tadiesels.com/perkins-4108.html
You can clearly see the rear bell housing bolt on mounting bracket. Some rear mounts are actually on the transmission. If the mounts were cast with the block you'd most likely be missing a chunk of engine block. If the packing gland is cast into the hull/stern tube as many space limited shaft seals are, with little to no flexible hose then you'd have some serious repairs.

Matter of fact yes ...I own one. It's a 79 model.
But if you think they all look the same your missing some info.
This 108 pictured by the OP uses a different drive setup than my velvet drive.

I believe he's using a manual gear box, though I cannot see the model.
And, I can say that crankshafts in engines are not on plane with most prop shafts.

Most use some type of dropped output shaft flange facing.
Example: V drives...
Output shafts on gear boxes are inline with the props shafts coupler facing.
Not a crank shaft in general.

You also forgot some areas that take some of the shear load of say a log or strike to the prop.
This can result in a prop shaft key, or coupler key shear, even damper plates tear out on strikes.

Never yet have I even heard of a crankshaft being bent from a crab pot line or even a ground strike. And since they are not bolted together I think it's a very rare event.
Remember the Main Caps on the engine hold these components.

They don't float around in the air like shafts do.
The reason that Packing glands survive better in this instance is the increase in holding the gland to the shaft log.

Packing glands "cast onto shaft logs" who does this?
Maybe a fishing vessel, with larger than a 2" shaft, maybe?
And, yes these huge engines may be in line with a crank shaft,
Because the shafts have a lot of weight, so they are supported by the shaft log.
This is different than most recreational vessels.

Remember, packing gland hoses are stiff, but flexible, they give as much as thin little wisps of rubber supplied with dripless setups.

So, yes I have seen a 4108, I own one, and work on boats for a living.
Boatyarddog

[stormalong]

Originally Posted by Boatyarddog

Remember, packing gland hoses are stiff, but flexible, they give as much as thin little wisps of rubber supplied with dripless setups.
Boatyarddog

The hoses on standard packing glands are no where near as flexible as a PSS bellows. The bellows are not flimsy. They are very elastic and the reason they are replaced periodically is because they loose their elasticity. I said in an earlier response that the PSS is probably not damaged. I wrote that because they are so flexible.

BTW, From the picture I am guessing that the OP has a Hurth/ZF marine transmission.

[Boatyarddog]

Originally Posted by stormalong

The hoses on standard packing glands are no where near as flexible as a PSS bellows. The bellows are not flimsy. They are very elastic and the reason they are replaced periodically is because they loose their elasticity. I said in an earlier response that the PSS is probably not damaged. I wrote that because they are so flexible.

BTW, From the picture I am guessing that the OP has a Hurth/ZF marine transmission.

Probably a ZF.
As stated, packing gland hoses are more robust but flexible.
Most shafts operate within a 1/2" all around them in the shaft log.
So, there is little room for either to flex to the point of breaking.
I'd go with a gland everytime for the reliability, also that hose will be changed out every 20 years, not every 5.
Boatyarddog

[Engine man]

I have lots of 4.108M parts here, including the engine mount bracket that broke. Let me know what you need.

Also ZF / Hurth or Twin Disc / Technodrive transmissions, new, used, or rebuilt, damper plates, Transmission adapter plates, Vee drive type transmissions, etc.

Yes, I have seen a very similar situation that involved a Perkins powered sailboat and a fishing net. The aluminum transmission adapter plate shattered into several pieces, and the transmission dropped into the bilge. May I suggest you CLOSELY inspect the adapter plate for cracks? Joe

Originally Posted by libbymr

A couple weeks ago coming down from Seattle we wrapped pot around the prop shaft at night, didn't quite seize the engine but it got close. We were able to spin off the line but the damage was done,

It appears to have messed of the PSS seal( lots of leaking now), bent the prop shaft and sheered off the brackets for the engine mount, throwing everyhing out of alignment. The latest discovery was the engine mount being sheered off from the engine.

Has anyone seen anything like this before? Has anyone ever had to replace the brackets AND the mounts?

Vessel was supposed to depart to Mexico on May 1 but with this I don't think that's happening.

Attachment 254787 Photo