Bullet Proof Diesel

[Catalpa1]

Perkins

[captain58sailin]

I am an old guy, I like old style diesels, I understand them and they understand me.

[Cheechako]

When running the two Yanmar's in my Cat at the specified ~3500 RPM the boat sounded more like an airplane than a boat. Neither engine lasted 2500 hours. So much for following the Yanmar mechanic's recommendations. Pistons broke in both engines.
I know I've said this a million times, but the difference between a commercially rated engine and pleasure rated engine is most often simply a lower rpm specification. That should tell you something.

[Exile]

Originally Posted by Catalpa1

Perkins

Are these still in production??

[a64pilot]

My Yanmar is 27 yrs old and had 500 hours on it. I've put a little over 100 on it in the last couple of months, near as I can tell it's in great shape, burns no oil etc.
Yes a Diesel should be run frequently, under load and at operating temp for 30 min or so before being shutdown, but sitting for long periods apparently doesn't kill them either or mine would have died long ago.

[Exile]

Originally Posted by Cheechako

When running the two Yanmar's in my Cat at the specified ~3500 RPM the boat sounded more like an airplane than a boat. Neither engine lasted 2500 hours. So much for following the Yanmar mechanic's recommendations. Pistons broke in both engines.
I know I've said this a million times, but the difference between a commercially rated engine and pleasure rated engine is most often simply a lower rpm specification. That should tell you something.

3500 rpm sounds closer to the mfg.'s max. rating, even for a higher revving (often turbo) Yanmar. I thought the rule of thumb was to take the max. rated rpm (making sure the prop is pitched to allow the boat to achieve this rpm), and 80% of max. rated rpm would be max. "sustainable" rpm. I've also heard that 60% of max. rated rpm is a rough guideline for achieving the best fuel efficiency.

On my naturally-aspirated, 82-hp Westerbeke, the max rated rpm = "3500-3600" according to the manual. So max sustainable rpm is approx. 2800 rpm, with best fuel efficiency closer to 2100-2200 rpm. This seems to pan out in my actual experience. It is important to have the prop correctly sized, however.

As mentioned in a previous post, I have also been advised that it is beneficial to occasionally run at WOT for 5 mins. or so to burn out/clear the build-up of soot. As it's been explained to me, marine diesels like mine that are water-cooled and also use a raw water heat exchanger are much more efficient than their land-based equivalents in cooling the engine. This can result in the build-up of harmful soot deposits over time, especially if the engine is idled a lot for battery recharging or to run refrigeration, etc.

No personal expertise here, just info from some pros I've talked to along the way.

Dan

[CarlF]

The hundreds (thousands?) of charter boats operated by the Moorings use Yanmar engines and have for decades. These are operated by charterers who have no interest in taking care of the engine. As few Moorings boats have generators, most charters have to run the engine at low RPM's every day to charge batteries. A really bad thing for any diesel.

I checked the Moorings brokerage site. Some of the listings show the engine hours. Here's one with 3900 hours on the Yanmar engine. Others all seem to be between 2500 and 5000 hours.

http://www.mooringsbrokerage.com/use...?BoatID=597497

Do you really think you're going to run your engine enough to get to these sorts of hours?

For the Moorings, a "seized" engine will put a boat out of service for a week - a month if the location is someplace like Tonga. This would mean thousands of dollars in lost charter revenue. Far worse than any difference in purchase cost difference between a Yanmar, Beta or what have you.

I'm confident that Moorings has employees who job it is to evaluate reliability. If Yanmar's were statistically more likely to fail than another engine (that would fit in the engine room), the Moorings would switch.

[marlinmike]

Another great resource other then this site is boatdiesel.com, and one guy at that site who has published many articles on longevity is Tony Athens. One part of his response which continueally comes up, it's not the color of the engine, but the nut behind the wheel that will determine how much life you get. Of course he is also including all the maint aspects into the marine diesel, propped correctly and run correctly.

[leftbrainstuff]

Any of the older non electronic diesels are good options. Perkins 4-108 and 4-236 are good workhorses. We have a 4-236 main engine and a Kubota generator.

The challenge you have is not statistically whether one brand is better than another but whether you are confident or experienced enough to not pick a dud.

For any potential purchase you want an engine that's been well maintained. Due diligence means you'll conduct a visual inspection, a load test, an oil test and perhaps a compression test. With this information you're able to make an informed decision.

Sent from my GT-I9300 using Cruisers Sailing Forum mobile app

[captain58sailin]

Engines painted blue last longer.

[FlyingCloud1937]

Originally Posted by captain58sailin

Engines painted blue last longer.

Actually engines painted WHITE last longer, no matter their native color.

A white engine, will alert you to any leakage long before it can become a catastrophic event, oil, water, fuel, and over heat.

This depends on you, to first inspect your engine room each and every time, you do a cold start-up.

Then it requires you to address any maintenance the minute you see the tell tell signs.

Lloyd

[captain58sailin]

I knew if I offered that outlandish piece of wisdom, someone would come along and counter it. Regardless the color, if you perform a careful inspection before start up you will catch things before they become catastrophic.

[dannc]

I have a JD tractor powered by Yanmar. The Yanmar engine is outstanding and very reliable after 14 years. The engine uses no oil what so ever.

If it was me, I would find out what Yanmar engine is in the boat and see if I can get parts for it from a JD dealer or other tractor dealers. I use JD filters for my Ford truck because it has been cheaper and easier to get the parts from JD than even the local auto parts store.

Get an oil sample and to the lab. I have used Blackstone Labs for years. If they have done tests on the same engine model, they will provide averages on your report from those engines, as well as your sample, for comparison sake.

I was shocked to see Yanmar's reputation on the boating websites because they have a good reputation in tractor engines.

Later,
Dan

[a64pilot]

How bad is overpropping?
My engine should turn 3600 RPM, full bore, but will turn only 2700. Tach has been verified accurate and prop is spotless, so it's obviously over pitched.
I cruise it at 2000 and it seems happy there, full throttle you can tell she is straining, but even then, no black smoke.
I know I'm giving up significant HP by not letting her turn up, but are we sure this is damaging? What specific harm does it do, she's burning all the fuel as evidenced by lack of smoke.

[a64pilot]

Originally Posted by dannc

I was shocked to see Yanmar's reputation on the boating websites because they have a good reputation in tractor engines.

Later,
Dan

My feelings exactly, My JD 997 lawnmower is a 30 hp Yanmar that is always run at max RPM as you run mowers that way. Had it for ten years and except for one belt that a stick got into, 0 un-scheduled maintenance