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Old 31-05-2017, 05:53   #46
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Re: Yanmar 3GM30F engine--One sick little engine

UPDATE TO ALL on our engine: On Monday this week, our Yanmar mechanic came to the boat and in an hour and a half had our engine out and on a cart to the shop. I include photos below. We used to main boom to lift the 300-lb. engine out the main companionway. Yesterday, Tuesday, he had the engine pulled apart to see the inside, and the issues are a bit worse than first thought, but repairable. First, all three cylinders have some corrosion on the inside surfaces. These will have to be bored out and either fitted with over-sized pistons, or bored out a little more and sleeved with new sleeves and fitted with same-size pistons. The mechanic is getting estimates for both of these options.

Two of the pistons are in pretty bad shape and need to be replaced. The third piston is not so bad, but we are going to replace it anyway so that all three are new.

All the valves need to be replaced, and we'll also probably replace the injectors.

Number two cylinder has not been firing well, if at all (although the engine does not run rough). That cylinder has a lot of carbon build-up on the head.

The crankshaft, the main bearings and the piston crank bearings are all in good shape.

Projected cost prior to opening the engine was about $6,000 to $6,500, so the final tally will likely be a bit more than that to account for reboring the block.

In the meantime, we are busy cleaning out the engine space to clean up 30 years of grime. We also discovered that a mounting bolt is missing from one of the engine mount brackets--one of two bolts that fastens the port rear angle bracket, on which the engine mount sits, to the wood engine girder--bolt, nut and washers are totally missing. Obviously, that will be replaced.

So now we know the condition of the engine and can carry out the necessary repairs. It is really good that we are doing this so that the engine will be in tip-top shape for going further on our cruise around the world.

Pictures:
3081--engine coming out of the boat
3097--begin disassembly
3085--the three pistons
3086--the block
3087--close-up of the cylinder walls. This one is the worst, but all have a similar pitted condition
3102--the cylinder head

I'll post other updates as I learn them.

Eric
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Old 31-05-2017, 07:00   #47
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Re: Yanmar 3GM30F engine, burning oil--Why? Can you help?

Glad you are on the move to getting rebuilt. Honestly I have seen way worse diesels that still ran good. Tough little things.

Enjoy PR. I am headed there in September for a small vacation.
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Old 31-05-2017, 07:49   #48
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Re: Yanmar 3GM30F engine, burning oil--Why? Can you help?

In my opinion, worn engine, corrision, excessive carbon all equal dirty oil probably with metal particals which work on wear. A worn engine, cylinders , pistons will put less stress on your mains and wrist pins. When you rebore new pistons and rings the stress, pressure on mains crank will be greater so wear on those parts will be greater than before. I would turn crank, new bearings new connecting rods and new pistons. metal can have fatique fratures that are un seen and will give out when new tight parts are introduced. I have seen many engines half rebuilt, ie. heads, rings only to blow out he lower end. I m not out to spend your money, only to give you a " no worry" state of mind.good luck
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Old 31-05-2017, 15:00   #49
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Re: Yanmar 3GM30F engine, burning oil--Why? Can you help?

Wonder why a rebuild would cost so much. Rebuilt a Landrover 4 cylinder gas for a little more than a $1,000. That included a rebore, oversize pistons, porting, polishing, and milling, new pistons and springs, new diesel cam, and $500 dollars labor for a mechanic to look over my shoulder while I did it. The engine was gas but the LR 4 was designed as a diesel and converted to gas with the main change being different pistons and the petrol feed goodies. A diesel will cost more as there is the cost of rebuilding the injectors, cheap, and the injection pump, expensive, but still nowhere near $6,000
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Old 31-05-2017, 18:40   #50
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Yanmar 3GM30F engine, burning oil--Why? Can you help?

Quote:
Originally Posted by roverhi View Post
Wonder why a rebuild would cost so much. Rebuilt a Landrover 4 cylinder gas for a little more than a $1,000. That included a rebore, oversize pistons, porting, polishing, and milling, new pistons and springs, new diesel cam, and $500 dollars labor for a mechanic to look over my shoulder while I did it. The engine was gas but the LR 4 was designed as a diesel and converted to gas with the main change being different pistons and the petrol feed goodies. A diesel will cost more as there is the cost of rebuilding the injectors, cheap, and the injection pump, expensive, but still nowhere near $6,000


Because it's not a Marine engine , and you did it.
Been a few years ago, but I had figured on $1,000 a cylinder for an aircraft engine overhaul doing it myself as I am licensed to do so. More now I am sure, but people regularly pay $30,000+ for a 6 cyl aircraft engine overhaul.

Difference of course is you don't have to cover shop overhead, unemployment Insurence, medical etc. Mechanic may only see $20+ an hour, but may cost employer twice that, and of course employer has to make a profit, it adds up.
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Old 01-06-2017, 01:47   #51
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Re: Yanmar 3GM30F engine, burning oil--Why? Can you help?

+ Yanmar $$$$$

I love my 3JH3 and do all my own work but I still get sticker shock from the parts.

Cheers
Tom
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Old 01-06-2017, 06:17   #52
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Re: Yanmar 3GM30F engine, burning oil--Why? Can you help?

I was surprised that it is being done that cheaply. I was wondering if doing the bottom end would not be prudent although I feel it must mic. out OK and will get bearings and seals.
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Old 01-06-2017, 07:06   #53
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Re: Yanmar 3GM30F engine, burning oil--Why? Can you help?

The biggest problem with a rebuild is you still have all those old parts hanging from the engine. Alternator, starter and high pressure pump to name 3. Then there are the water pumps (both), heat exchanger and mixing elbow and maybe even the hoses. So a complete rebuild isn't very complete.
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Old 01-06-2017, 07:17   #54
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Re: Yanmar 3GM30F engine, burning oil--Why? Can you help?

I have read your post and responses with interest, we have had our Yanmar 3GM 30F since it was installed new in 1993. We have 2500 hours on the engine of that 300 hours were added in the last 12 months. We have done all routine maintenance, oil change every 100 hours, had the engine checked by trained Yanmar professionals on a regular basis, heat exchanger cleaned in 2016, had the fuel polished regularly, had the engine oil examined professionally every two years, and we run the engine every month. The engine uses at most half a pint of oil in 12 hours of motoring

Our story began last week when our engine struggled to start, but it did eventually start with judicious use of the throttle. Once started the engine sounded normal. We motored for 5 hours and upon entering a new marina we bought fuel, the engine started perfectly and we moved to our berth. Six days later we were ready to leave, engine would not start at all. Fortunately, there is a local Yanmar agent nearby, they checked the engine and discovered there was no compression in one of the pistons. They pulled the engine and the result is a crack in the cylinder head, water in the cylinders-, damage to rings and valves, and possibly a cracked block (we have to spend thousands to find out if the block is cracked and then if it is…). We had already decided to get a new engine and it will be installed next week.

Here is my question, Yanmar says the engine should be good for 10,000 hours and we only had the one difficult start before a complete failure, what did we do wrong or miss to indicate that we had a serious problem?
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Old 01-06-2017, 07:28   #55
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Re: Yanmar 3GM30F engine, burning oil--Why? Can you help?

Quote:
Originally Posted by AliOops View Post
I have read your post and responses with interest, we have had our Yanmar 3GM 30F since it was installed new in 1993. We have 2500 hours on the engine of that 300 hours were added in the last 12 months. We have done all routine maintenance, oil change every 100 hours, had the engine checked by trained Yanmar professionals on a regular basis, heat exchanger cleaned in 2016, had the fuel polished regularly, had the engine oil examined professionally every two years, and we run the engine every month. The engine uses at most half a pint of oil in 12 hours of motoring

Our story began last week when our engine struggled to start, but it did eventually start with judicious use of the throttle. Once started the engine sounded normal. We motored for 5 hours and upon entering a new marina we bought fuel, the engine started perfectly and we moved to our berth. Six days later we were ready to leave, engine would not start at all. Fortunately, there is a local Yanmar agent nearby, they checked the engine and discovered there was no compression in one of the pistons. They pulled the engine and the result is a crack in the cylinder head, water in the cylinders-, damage to rings and valves, and possibly a cracked block (we have to spend thousands to find out if the block is cracked and then if it is…). We had already decided to get a new engine and it will be installed next week.

Here is my question, Yanmar says the engine should be good for 10,000 hours and we only had the one difficult start before a complete failure, what did we do wrong or miss to indicate that we had a serious problem?
That is a good question. I bet Yanmar won't answer it.
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Old 01-06-2017, 07:30   #56
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Re: Yanmar 3GM30F engine, burning oil--Why? Can you help?

One item you may have missed, and I'm just guessing here, is the anti-siphon valve between the heat exchanger and the injection elbow.
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Old 01-06-2017, 08:46   #57
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Re: Yanmar 3GM30F engine, burning oil--Why? Can you help?

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Originally Posted by DeepFrz View Post
One item you may have missed, and I'm just guessing here, is the anti-siphon valve between the heat exchanger and the injection elbow.
By missed you mean? We don't have the engine anymore so can't check but interested to know what you meant?
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Old 01-06-2017, 09:13   #58
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Re: Yanmar 3GM30F engine, burning oil--Why? Can you help?

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By missed you mean? We don't have the engine anymore so can't check but interested to know what you meant?
I as curious also. I never had one and may have had one on something else and didn't know it?
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Old 01-06-2017, 10:11   #59
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Re: Yanmar 3GM30F engine, burning oil--Why? Can you help?

[QUOTE=AliOops;2404750]I have read your post and responses with interest, we have had our Yanmar 3GM 30F since it was installed new in 1993. We have 2500 hours on the engine of that 300 hours were added in the last 12 months. We have done all routine maintenance, oil change every 100 hours, had the engine checked by trained Yanmar professionals on a regular basis, heat exchanger cleaned in 2016, had the fuel polished regularly, had the engine oil examined professionally every two years, and we run the engine every month. The engine uses at most half a pint of oil in 12 hours of motoring

Our story began last week when our engine struggled to start, but it did eventually start with judicious use of the throttle. Once started the engine sounded normal. We motored for 5 hours and upon entering a new marina we bought fuel, the engine started perfectly and we moved to our berth. Six days later we were ready to leave, engine would not start at all. Fortunately, there is a local Yanmar agent nearby, they checked the engine and discovered there was no compression in one of the pistons. They pulled the engine and the result is a crack in the cylinder head, water in the cylinders-, damage to rings and valves, and possibly a cracked block (we have to spend thousands to find out if the block is cracked and then if it is…). We had already decided to get a new engine and it will be installed next week.

Here is my question, Yanmar says the engine should be good for 10,000 hours and we only had the one difficult start before a complete failure, what did we do wrong or miss to indicate that we had a serious problem?[/QUOTE]

It's a defective engine design and a roll of the dice how long it will last. I had two in a Catamaran, 1992 vintage. One was replaced under warranty at about 500-600 hours. One had to be rebuilt at ..2300 hours IIRC. Both had cracked pistons. It may be the timeframe ... early 90's. It could also be that they want you to run the engine at like 3500 rpm. It sounds like a damn airplane at that rpm... I can see that cracking pistons...
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Old 01-06-2017, 12:46   #60
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Re: Yanmar 3GM30F engine, burning oil--Why? Can you help?

we never run above 2800rpm, higher only in an emergency and nothing like that in quite some time. We used to run at a lower rpm but added a maxprop and was told to up the rpm to 2800.
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