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Irrationally Exuberant
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I should have read this forum before sailing but luckily none of that happened to me. I hear everyone and I mean everyone who sails saying change your impeller. I changed mine and the new one sucked.....so I took it apart again and but the old one back in. Works like a charm. Plus, they work fine even with tabs broken so I don't see the huge emphasis here. When the engine overheats....change it. I don't have a temp sensor on my YSM 12 but it shuts off automatically when it gets too hot. This is usually, when I leave the seacock closed or the mixing elbow on the exhaust gets clogged/blocked which seems to happen about every 24 hrs of run time. I hear everyone praising the Yanmar engines but I've never had more trouble with an engine. The one thing I would praise is I've been able to fix everything....pretty easy to work on. Well almost....currently I'm mounting a little 8 hp evinrude to the transom...not sure whats wrong with the Yanmar now. Won't spin. Probably water in the chamber which .... rebuild or replace with something better. It's on a Hunter 30 and only ran 4.5 knots. I'd love to get something that'll get me 6.0 knots.
I guess you're not kidding here. :eek: Running your engine until it cuts out from overheat and using that as your impeller wear indicator is just a bad idea. Probably not good for the engine, but also, this event might just happen at the worst possible time--when you really need your engine. There are lots of sailboat parts that give nice obvious indicators when they've failed, but best not to go there.
 

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Super Moderator
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6,752 Posts
put off dealing with a worn cutlass bearing, which leads to excessive engine vibration, which leads to a ten pound alternator shaking back and forth, which leads to the timing chain cover breaking open where the alternator bolts on.
Sounds like an old Universal diesel with the old alternator bracket?
 

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the pointy end is the bow
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6,265 Posts
Sounds like an old Universal diesel with the old alternator bracket
It was a little Kubota 2 cyl (Westerbeke). We sailed it into Bellingham, where I mocked up a new alternator bracket out of cardboard, took it to a local machine shop and they had a new replacement bracket cut out in about a half hour. Then I marinetexed the the timing belt cover back together and ran her that way for another four years.
 

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Don Radcliffe
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398 Posts
Another sure-fire way to make mechanics rich is to have a leak in your fresh water cooling system, let the engine boil over, then shut it down and add cold water. If it doesn't crack the block it will at least warp the head.
 

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clueless
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184 Posts
Being that this is my field i can say with out a pause that the number #1 killer of Diesel engine is... Water...
Water in to an intake acts like ball bearings and does not compress everything around it will, rods get shorter, piston ring lands get smaller etc. Water from the fuel system is the most common the second is the air intake system.
 

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clueless
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184 Posts
Another sure-fire way to make mechanics rich is to have a leak in your fresh water cooling system, let the engine boil over, then shut it down and add cold water. If it doesn't crack the block it will at least warp the head.
Actually, cold water in a hot engine gets steamed off. The water becomes steam and forces the engine to hyper contract which causes cracks. Diesels are not as prone to cracking as gas engine due the heavy construction of the components. They will survive it, i have seen it happen more times than a failure. The best thing to do is allow it to cool then run water slowly and check for damage. Engine with liners are the most prone to damage as the high heat crystallizes the o rings that seal the liners. Then water just fill's the crank case.
 

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I'm guessing you speak from experience. If I wasn't getting water flow I would change it again, but I'll start the motor.....verify water is flowing heavily out the exhaust and moving through the clear tube after my impeller. The old crappy one moves it just fine....the new one jams or doesn't quite fit in right even though it looks the same and was the part # according to the engine so I put the old one back in. When the engine has overheated (4x since I've owned) it shuts down on it's own...but I've run this baby for stretches of 40 + hrs straight. During those 4 shut downs what kind of damage are we talking? All 4x it started back up within 30 min no problem and the problem every time was clogged mixing elbow.
 

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Clogged with what? Maybe a major rethink regarding the whole cooling system is in order. 5thx at the breakwater waiting 30 min as the hull grinds could by a reality. Meanwhile I'd be wondering 'Did I glaze or score the cylinders or damage the rings.?'
 

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Capt Len - Clogged with a carbon build up of salt water (Yanmar Engine is Salt-Water Cooled) and carbon. It blocks very easily in the mixing elbow and seems to be a common problem from reading the other threads and forums. When I clean it I basically punch it out with a screwdriver and coat hanger to clear the entire mixing elbow. Then she runs clean and smooth until the next clog.
 

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Maybe needs a bigger elbow and or more cooling water going thru it to keep the deposit from forming. If it were mine I'd put in a heat ex and solve it .Engine would probably thank you.
 

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I just had a long conversation today with an experienced diesel mechanic and he said it is important to mix coolant 50/50 before putting it in the engine. He said if you pour in one gal of straight coolant the a gal of water it will not mix properly in the engine and the engine can rust and or freeze.
I thought that was not obvious.
 

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Closet Powerboater
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3,925 Posts
Discussion Starter #34
There is some good info on this thread, but some things on here make me shudder. My 20 HP Beta Marine diesel has 400 hours and I am doing everything I can to try and make her last many, many years.
A collection of things that make you shudder is exactly what I was after in this thread. I wanted to collect the mistakes that are easily avoided that will suddenly and irreparably destroy the expensive iron monster in the bilge.

Congradulations on your new engine. Please do me a favor. Have a normal conversation down below while it's on. That's all. When you do, think of me wishing I had ear protection for my Perkins. :)

Try not to get too worried about your diesel and your maintenance of it. Whenever I read Nigel Caulder's books I feel like a bad parent. It seems the the ideal maintenance schedule would have me NEVER actually out cruising. Try and remember though that diesels really are robust. Good/fanatical maintenance may mean the difference between 7 and 10K hours, and shoddy vs decent maintenance may mean the difference between 4-7Khrs but they will all run for a long time on whatever modicum of maintenance and love you give them...... as long as you don't destroy them with a big mistake.

I try to learn what big mistakes to avoid and try to enjoy my boat and not sweat the details of maintenance too much.

MedSailor
 

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Learning the HARD way...
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7,141 Posts
It was a little Kubota 2 cyl (Westerbeke). We sailed it into Bellingham, where I mocked up a new alternator bracket out of cardboard, took it to a local machine shop and they had a new replacement bracket cut out in about a half hour. Then I marinetexed the the timing belt cover back together and ran her that way for another four years.
Westerbeke / Universal takes Kubota engines, and marinizes them.. The Universal M25 was notorious for shaking the alternator, leading to a crack in the timing case and oil in the bilge :(

The whole story is listed here..
 

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Over Hill Sailing Club
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3,688 Posts
Treat it too good by running at low rpm. With a Yanmar, This will surely result in glazed piston walls and a low hour smoker requiring a hone and re-ring...ding, ding, ding.
 

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Hi all,

The boat I just sold was prevented from overheating in the following way by the previous owners:

After forgeting to open the cooling seacock and causing some damage, they ALWAYS put the ignition keys on the handle for the seacock. That way you could not start the engine without touching (and opening) the cooling water. I adopted their practice and never forgot to open the cooling line before starting the motor. Also, I replace the impeller every year. Very cheap insurance against some of the problems discussed here.

Cheers, Bill
 

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SV Skalliwag #141
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744 Posts
Running your engine with a bypass oil filter system. Take it out before it springs a leak and you destroy your engine while running with insufficient oil pressure.
 

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Owl
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270 Posts
I just had a long conversation today with an experienced diesel mechanic and he said it is important to mix coolant 50/50 before putting it in the engine. He said if you pour in one gal of straight coolant the a gal of water it will not mix properly in the engine and the engine can rust and or freeze.
I thought that was not obvious.
What if you pour in a quart of coolant, then a quart of water, then a quart of coolant, then a quart of water, then a quart of coolant...
 

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Registered
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186 Posts
Have your transmission seize outside of Ensenada on the way to Baja Naval for a bottom job.

Have the folks at Baja Naval remove the transmission and send it to the states to be rebuilt.

Have the folks at Baja Naval reinstall the transmission with the pressure plate installed backwards.

Run the engine for 16 hours.

Result 1 seized Yanmar 4JHE.

Try to get to the friendly folks at Baja Naval to cover the cost of the rebuilt diesel - fruitless.

Repower the boat with a new Yanmar 4JHE - a few thousand more then rebuild.

Marc Hall
Crazy Fish, Crealock 37, Hull 207
 
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