Is my Diesel Mechanic brilliant or a fool?

[ghockaday]

You are going to drive your self crazy.

[fritz3000g]

You are going to drive your self crazy.

You mean with the transom-mounted outboard, or worrying about the engine generally?

In the past, I've had so many frustrating experiences with marine engines (all outboards in my case) that I'm prone to strongly distrust them. Some examples:

• Yamaha 10 hp that would work for 10 minutes then drop to 20% power till it cooled off. Tried to diagnose for 2 years, including through an engine-rebuild class. Eventually I messed up the mount raising line and the motor fell off the boat in 200 ft of water.
• Mercury 2.5 hp that shredded the impeller when out on the water.
• Tohatsu 5 hp that worked great till we were on vacation 6 hours away when it died on the water and we couldn't find anyone to repair, basically ruining the island-hopping vacation plan (long story). Spent a year myself and sent to a mechanic who couldn't diagnose it (started for them). Eventually found out it was a kill switch attachment which was just a little too thin, which intermittently fired the kill switch.
• Same Tohatsu 5 hp slipped off the motor mount last summer and fell in the water 4 hours away. Recovered it, but had to cancel our sailing plans for that vacation.

So, yeah. I've sailed into the dock a lot and had to cancel two sets of vacation plans. Really hoping to avoid that in the future. Also really don't want to spend $15k on a repower.

[JD-MDR]

[quote="fritz3
I do have a dinghy. I've been thinking of attaching a motor mount to the stern as a way to store the dinghy motor. If that could lower the prop into the water then it could be a backup motor. [/quote]
I did that on my previous boat it had the ysm12 and was so slow. The 5 hp outboard did give it a little boost. I was really worried when I bought that boat. The motor was badly neglected and not running. I had to have someway to propell it. Sometimes you cant worry what people think. I wasnt a very experienced sailor and Like I said I like my self-sufficientcy

[fritz3000g]

For anyone who has a Yanmar GM series motor, I've noticed that the owner manual (at least the 1980 version) is awful. It's badly formatted, poorly organized, and even self-contradictory. On the other hand, the service manual is fantastic, one of the clearest technical documents I've ever encountered. How the same company produced both is beyond me.

Here are a couple quotes from chapter three: Operation, Lubrication, Maintenance and Tune-Up.

Perform an engine tune-up as needed at periodic intervals to maintain maximum engine performance. If the engine is used infrequently, perform a tune-up at least once a season. A tune-up consists of the following:

1. Compression Test
2. Valve Adjustment
3. Idle speed adjustment

...
A compression test measures the compression pressure at the end of the compression stroke. Its results can be used to assess general cylinder and valve condition. In addition, it can warn of developing problems inside the engine.

That last quoted sentence "it can warn of developing problems inside the engine" is the thing I'm seeking. For that reason I've really appreciated the tips about oil testing. I'm also eager to better understand the extent to which lowered max RPMs are a sign of developing problems, and I really wish that the manual covered that (but it doesn't).

Elsewhere in the manual it describes what you need to do if you do develop problems inside the engine, including expensive things like re-boring the cylinder.

The other thing I find compelling about doing tune-ups is that it forces me to spend time carefully looking at the engine. Like they say with gardening ("the gardener's footsteps are the best fertilizer") it makes sense to me that the mechanic's eyes are the best preventative maintenance.

[tjr818]

On our 27 when we first had her we could not get the YSM8 up to speed, I was new to the game and just assumed that a thirty year old engine might just be a little tired. The second season I figured out that the only problem with that YSM8 was the throttle linkage, it would not move the throttle to full open, a simple cable adjustment and every thing was as it should be and we never had a problem reading full RPMs again. You might want to check that.

[ghockaday]

You are going to drive your self crazy.

You mean with the transom-mounted outboard, or worrying about the engine generally?

In the past, I've had so many frustrating experiences with marine engines (all outboards in my case) that I'm prone to strongly distrust them. Some examples:

• Yamaha 10 hp that would work for 10 minutes then drop to 20% power till it cooled off. Tried to diagnose for 2 years, including through an engine-rebuild class. Eventually I messed up the mount raising line and the motor fell off the boat in 200 ft of water.
• Mercury 2.5 hp that shredded the impeller when out on the water.
• Tohatsu 5 hp that worked great till we were on vacation 6 hours away when it died on the water and we couldn't find anyone to repair, basically ruining the island-hopping vacation plan (long story). Spent a year myself and sent to a mechanic who couldn't diagnose it (started for them). Eventually found out it was a kill switch attachment which was just a little too thin, which intermittently fired the kill switch.
• Same Tohatsu 5 hp slipped off the motor mount last summer and fell in the water 4 hours away. Recovered it, but had to cancel our sailing plans for that vacation.

So, yeah. I've sailed into the dock a lot and had to cancel two sets of vacation plans. Really hoping to avoid that in the future. Also really don't want to spend $15k on a repower.

Worrying about a 40 year old diesel. It is going to not start or let you down at the most inopportune times. They sit too mcuh, run to little and are kept in a damp location. At least you are not in saltwater, that is much worse. Boats in general can very very aggravating at times. We went with an electric inboard when ours failed. Due to the extremely high cost to re-power diesel. Not looking for it to be perfect either.

[Dick Kobayashi]

In Line Raw Water Filter

Something along these lines is what I had

https://www.westmarine.com/buy/jabsco-- ... cordNum=75

Be careful though. There is very little room between the hull and the water pump and the inlet hose diameter is not large. Make sure your strainer will fit conveniently in the space available and accept the relatively small ID hose. The water pump itself is small and CRITICAL so a few bucks and a little effort to protect it is worth it.

[fritz3000g]

We went with an electric inboard when ours failed.

Interesting! You went with one of these? https://electricyacht.com/shop/

Is there a thread or another place where you've described your experience?

It is going to not start or let you down at the most inopportune times. They sit too mcuh, run to little and are kept in a damp location. At least you are not in saltwater, that is much worse. Boats in general can very very aggravating at times.

Sounds like mounting an outboard as backup might be a good option.

Something along these lines is what I had: https://www.westmarine.com/buy/jabsco-- ... cordNum=75

Thanks!

The second season I figured out that the only problem with that YSM8 was the throttle linkage, it would not move the throttle to full open, a simple cable adjustment and every thing was as it should be and we never had a problem reading full RPMs again. You might want to check that.

Thanks will do!

[ghockaday]

We went with an electric inboard when ours failed.

Interesting! You went with one of these? https://electricyacht.com/shop/

Is there a thread or another place where you've described your experience?

No , still the motor, battery bank, charger and 48 to 12 converter with a DIY install will take you up to 10K. I

made the mistake of buying a boat I loved, the looks and stability of her. When we got this boat and we love to sail her, I was looking for a Pearson 26 (outboard) or a CD 25 with an outboard. Brand new repower for little compared to a diesel. These old diesels are getting old and unreliable not matter what anyone thinks, that is my opinion of them. Watch any of the youtubers with the old boats.

I also looked at the Atom conversion but did not have the heart to do it to her.

[fritz3000g]

I also looked at the Atom conversion but did not have the heart to do it to her.

This?

https://atomvoyages.com/articles/the-im ... oard-well/

Since I'm open to hanging an outboard on the stern as a backup, I'd also be open to creating a motor well or doing a custom electric install with four batteries and an inverter generator.

[Kailua Kid]

I have operated diesels including in the marine industry for decades. I would say your mechanic is neither brilliant (a little imprecise in his or her use of language) nor a fool (what the mechanic has told you is essentially correct). Also, to me it sounds like the mechanic is not trying to game you in any way. Let me add that I have been somewhat of a “motor head” since at least middle school and most of my wrenching early on involved gasoline engines. One thing I would pass along is that many things that are true concerning gasoline engines are not true as regards diesel engines. They are different in many ways and I have often been guilty of attempting to troubleshoot diesel engine issues using diagnostics based on gasoline engines. With clean high quality oil, changed at 100 hours of operation in most instances, and clean fuel (no water or algae or other contaminates allowed to enter the high pressure fuel pump, i.e. proper primary and secondary fuel filters), and adequate cooling water (ideally using a heat exchanger rather than a raw water cooling system especially if operating in salt water) and proper load to avoid over heating (clean bottom, clean wheel, correctly pitched wheel of the correct diameter), properly maintained heat exchanger and water pumps (both raw water and fresh water/internal pumps), most marine diesels will operate for decades and usually rust away from salt water corrosion before they wear out internally.

[ghockaday]

I have operated diesels including in the marine industry for decades. I would say your mechanic is neither brilliant (a little imprecise in his or her use of language) nor a fool (what the mechanic has told you is essentially correct). Also, to me it sounds like the mechanic is not trying to game you in any way. Let me add that I have been somewhat of a “motor head” since at least middle school and most of my wrenching early on involved gasoline engines. One thing I would pass along is that many things that are true concerning gasoline engines are not true as regards diesel engines. They are different in many ways and I have often been guilty of attempting to troubleshoot diesel engine issues using diagnostics based on gasoline engines. With clean high quality oil, changed at 100 hours of operation in most instances, and clean fuel (no water or algae or other contaminates allowed to enter the high pressure fuel pump, i.e. proper primary and secondary fuel filters), and adequate cooling water (ideally using a heat exchanger rather than a raw water cooling system especially if operating in salt water) and proper load to avoid over heating (clean bottom, clean wheel, correctly pitched wheel of the correct diameter), properly maintained heat exchanger and water pumps (both raw water and fresh water/internal pumps), most marine diesels will operate for decades and usually rust away from salt water corrosion before they wear out internally.

All very true as most all have stated. If WELL cared for for her 1/2 century, it won't be wear that gets her.

Yes, they will last decades and she is starting on her 5th.
Mine was in good shape except for the hole that rusted through the cylinder wall. Yours at least is sleaved I think the volvo is not.

[fritz3000g]

Yours at least is sleaved I think the volvo is not.

I don't think it is. The parts catalog (https://www.lsm-diesel.dk/2012/yanmar/p ... _123gm.pdf) shows replacement sleeves for the HM series but not the GM series. The manual also describes how to re-bore the engine.

With clean high quality oil, changed at 100 hours of operation in most instances, and clean fuel (no water or algae or other contaminates allowed to enter the high pressure fuel pump, i.e. proper primary and secondary fuel filters), and adequate cooling water (ideally using a heat exchanger rather than a raw water cooling system especially if operating in salt water) and proper load to avoid over heating (clean bottom, clean wheel, correctly pitched wheel of the correct diameter), properly maintained heat exchanger and water pumps (both raw water and fresh water/internal pumps), most marine diesels will operate for decades and usually rust away from salt water corrosion before they wear out internally.

Great! I'm hoping that's the case, though I have some reason to believe it might not have always been well maintained (starting trouble 5 years ago led to new valve assembly, infrequent impeller replacement lead to overheating two years ago and some burned paint on impeller housing). Turns out the oil wasn't replaced in the fall, so I have old oil I can send for analysis. I do want to do a compression test because the engine doesn't have a manufacturer's rating for a leakdown test, and I want to know how close to spec it's operating.

One question I have related to this is how much keeping your diesel tank clean and topped off matters when you have both a fuel filter (Yanmar) and fuel/water separator (Raycor) that you change every year? Keeping the tank full all year, then pumping it empty for winter (service manual recommends this) and figuring out where to dispose of the diesel seems like a lot of work if I have two filters dedicated to cleaning the fuel. Do they not work that well?

[JD-MDR]

One question I have related to this is how much keeping your diesel tank clean and topped off matters when you have both a fuel filter (Yanmar) and fuel/water separator (Raycor) that you change every year? Keeping the tank full all year, then pumping it empty for winter (service manual recommends this) and figuring out where to dispose of the diesel seems like a lot of work if I have two filters dedicated to cleaning the fuel. Do they not work that well?

All this talk has got me motivated again. I noticed some crud in my Racor since the diesel tank is low, less than 5 gal I will drain it and try to get all the crud pumped out this weekend.. I wish there was a drain plug and access panel.

[ghockaday]

Keeping fresh diesel is a constant problem with a day sailer. Keeping it full lets it get less condensate and algae but it also gets old. Not as bad as gas though. I I had a diesel again I'd keep it full all season, pump it out in the Winter and put it in the tractor. Like my gas generator. I pull the gas out and put it in the truck to keep fresh gas in the generator.