Another Yanmar Fault Found

[delmarrey]

On my 3JH4E this Friday, I went to loosen up the adjustment arm over the alternator, and the bolt that holds it to the motor goes right into the cooling water casting/jacket, which drips water when it's loosened. If this were to vibrate loose (aluminum threads) while out at sea it could cause an over heating problem. And Murphy's Laws says it would be just at the wrong time.

I would suggest installing and sealing a stud permanently and using a nut to hold the adjustment arm in place. This is what I'll be doing for security/safety.

I've emailed Yanmar suggesting a change.

[Tim Godber]

My new Yanmar arrives Thursday to replace an aged rusty Westerbeke! Better make that change because I do recall the same problem on my Sabre, when I made the same engine swap.

[rebel heart]

It's been beat-up-on-yanmar week lately.

[delmarrey]

I did received a polite reply from Yanmar already and the two main statements were "Yanmar prides itself on paying attention to our customers and making adjustments or improvements when and if possible." And, they will "forwarded a copy of this on to our engineering dept for them to review".

I also happen to mention that the exhaust mixer tube runs right down over the shifter level on the Kanzaki KM35P, which created installation problems.

[Blue Stocking]

Its interesting how some details of adapting originally land-based machinery to marine creates potential problem areas. A leaking tractor block would likely be caught and corrected before a buried-up sailboat engine.
The manner in which dedicated marine engines were built had a cost implication years ago.
Volvo engines, when they were entirely Volvo built, Had cylinder head studs and other tapped in fastenings, which were blind-tapped, and therefore never had fluids migrating up the threads.
Just sayin.

[gjordan]

A simple fix on any bolt that might come loose is to buy an aviation bolt of the same thread and size, with safety wire holes, and safety wire it in place. Be very careful of useing the proper torque for an aluminum block or you will strip threads and have a real nightmare.__Good Luck._____Grant.

[S/V Antares]

It appears the bolt goes through an aluminum pump housing into the iron block. A stud will not solve this as it needs a nut. I would remove the bolt, counter sink the pump housing bolt hole and use a BunaN or silicon rubber o-ring under a washer on the bolt holding the bracket. Its a compromise but that is what you get with adapting blocks for an unintended porpose.

Yanmar used to make purpose built marine engines. Economy of scale does not permit this anymore. Their current product line is based on industrial engines as are most of the available small diesels.

[Bash]

If you're starting a club comprised of folk who have broken alternator arm bolts on a Yanmar, sign me up. I wanna be president of the 4JH3-TE chapter.

[delmarrey]

Originally Posted by S/V Antares

It appears the bolt goes through an aluminum pump housing into the iron block. A stud will not solve this as it needs a nut. I would remove the bolt, counter sink the pump housing bolt hole and use a BunaN or silicon rubber o-ring under a washer on the bolt holding the bracket. Its a compromise but that is what you get with adapting blocks for an unintended purpose.

Thank you for noticing that. Bolt #34. I just assumed that it went into just the outside of aluminum from the shape of the casting. Now I have to worry about keeping the anit-freeze up to par. If that bolt were to ever start rusting, and I had to pull it for some reason, I'd have a problem of damaging the casting or breaking the bolt as Bash has experienced.

Holes in the bolt head would be a good idea and so would a castle nut on a stud. Either way the rust factor may come into the picture. Which do you all think would be worse???

I absolutely would not use a SS bolt/stud, the electrolysis between the metals with a liquid between then would be just as bad as rust. Especially of the heat exchanger/core stated transferring coolants.
I think an Inconel or titanium stud/bolt maybe a even better solution.


.

[donradcliffe]

It looks to me like gasket #16 should keep everything dry until you loosen bolt 34, then coolant will weep into the bolt hole from the large passage between the pump and the block. So there's no design problem--you just need a manual that says 'drain coolant before loosening bolt 34".

[delmarrey]

Originally Posted by donradcliffe

It looks to me like gasket #16 should keep everything dry until you loosen bolt 34, then coolant will weep into the bolt hole from the large passage between the pump and the block. So there's no design problem--you just need a manual that says 'drain coolant before loosening bolt 34".

Unless it vibrates loose or rusts inside the casting.

[Maxs]

Bolt #34 is the only one using a washer on the water pump.. It should help by avoiding the bolt getting loose from alt vibrations and while moving the arm for v-belt adjusting, and when lowering the arm in order to pull the cooler from the front.
I just assemble my pump, and forgot to install the washer. I'm going to leave it as is, and not do anything unless I notice some dripping. Hopefully, it won't give me any problems for a few years...

[Jim Cate]

Perhaps I am missing something, but why would you not simply coat the bolt with red Lock-Tite or equivalent? This would both seal the threads from leakage and avoid it backing out.

As to rust, the coolant should be full of anti-corrosive stuff so that the cast iron block doesn't rust.

Cheers,

Jim

PS Lots of engines have those bolts penetrating into the coolant in various places>

[delmarrey]

Originally Posted by Jim Cate

Perhaps I am missing something, but why would you not simply coat the bolt with red Lock-Tite or equivalent? This would both seal the threads from leakage and avoid it backing out.

The threads are screwed into the block not where it leaks. Locktite on a bolt that needs to be loosened occasionally is not a good idea IMO!

As to rust, the coolant should be full of anti-corrosive stuff so that the cast iron block doesn't rust.

There is a chance the coolant could cross over contaminating the antifreeze. If so, it's going to work on a steel bolt fairly quick.

BTW Cast iron has a lot of resistance to rust. That's why they use to plate the bottom of old wooden merchant tall ships with iron plate. e.g. Star of India

Cheers,

Jim

PS Lots of engines have those bolts penetrating into the coolant in various places>

Yeah! I've seen them and not liking the results.

[donradcliffe]

I don't think the coolant is leaking out bolt 34 around where it is threaded into the block--its leaking out because the hole for bolt 34 goes through gasket 16 right next to a coolant passage. My guess is that if you take a look at the pump casting, the coolant passage and the bolt hole are sealed off from each other.

If you drain the coolant below that level, dry things off, then tighten bolt 34, then add coolant, the bolt and its threads should stay dry. You should be able to torque the bolt in the iron block tight enough that it won't vibrate lose, but a little loctite wouldn't hurt.

Of course I'm happy I bought a Beta instead....