Over 10,000 Hours on an Original Perkins

[Cheechako]

Seems I was told the oil tests are only good if you use them over time for comparison..?
I believe Caterpillar does them.

[model 10]

You can analyse your own oil almost as well by opening up your oil filter and checking the contents. You can tell if there is bearing material, ring material cylinder wall etc, etc., and it's free.

[lifeofreilly57]

If you can rebuild it yourself then go for it, just remember things never break at a convenient time or place.
I have a 4-108 in my boat with 5000 hours on it, the motor runs well and doesn't do anything weird but like most of it's ilk it leaks oil, about a quart every 20 hours of run time. I know this because the previous owner put a stainless pan under the engine to contain it and I just change the oil absorbent mats, problem is I don't know if the engine ever ran too low on oil in the past.
If you are the second or third owner of the boat chances are you have no idea of the motors treatment by past owners, I'm the third owner of this boat and plan to rebuild the engine before we take off for parts unknown in 4 years. I've built numerous motorcycle and automobile engines in the past as well as the diesels in several of my previous boats and some auction boats I flipped. You never know the condition of the motor until you disassemble it. One engine that was "professionally maintained" by the previous owners boat yard sounded fine but just didn't seem right, I ended up pulling it and found that the internals were in terrible shape, the insides looked like they used tar for oil, I ended up having to regrind the crank and replace bearings for the crank and cam, it only had 3500 hours on it and it was a well know quality brand. Had I waited it would have become a grenade and turned into worthless scrap.Crank bearings and crankshaft journals can be damaged by an oil pressure fluctuation (starvation) and then run for hundreds of hours before total failure but when they do finally fail it happens quickly and catastrophically. That's a tough one to source inexpensively in another country.
If you can do the work yourself they are a relatively cheap engine to rebuild and not too complicated, you'll also become very familiar with the engine in that case which helps troubleshooting in the future.
Yeah, yeah, yeah, I know, it's a SAILBOAT and I'm sure someone will use that line but if you like having a motor in your boat that runs you'd be wise to make sure it's 100% before running off to places where good mechanics and a ready parts supply will be in short supply.
My current automobile has 320,000 miles on it and still gets 26 MPG, runs fine and uses no oil due to good maintenance, but I'm not driving to the far reaches of the earth with it either, if it breaks down now I can have it towed 10 miles to a dependable mechanic.
Used boat engines are a crapshoot, no matter how good the original manufacturer built them people can and will kill them through negligence.
Depends on how much of an adventure you're looking for.

[BZT54]

Originally Posted by lifeofreilly57

If you can rebuild it yourself then go for it, just remember things never break at a convenient time or place.
I have a 4-108 in my boat with 5000 hours on it, the motor runs well and doesn't do anything weird but like most of it's ilk it leaks oil, about a quart every 20 hours of run time. I know this because the previous owner put a stainless pan under the engine to contain it and I just change the oil absorbent mats, problem is I don't know if the engine ever ran too low on oil in the past.
If you are the second or third owner of the boat chances are you have no idea of the motors treatment by past owners, I'm the third owner of this boat and plan to rebuild the engine before we take off for parts unknown in 4 years. I've built numerous motorcycle and automobile engines in the past as well as the diesels in several of my previous boats and some auction boats I flipped. You never know the condition of the motor until you disassemble it. One engine that was "professionally maintained" by the previous owners boat yard sounded fine but just didn't seem right, I ended up pulling it and found that the internals were in terrible shape, the insides looked like they used tar for oil, I ended up having to regrind the crank and replace bearings for the crank and cam, it only had 3500 hours on it and it was a well know quality brand. Had I waited it would have become a grenade and turned into worthless scrap.Crank bearings and crankshaft journals can be damaged by an oil pressure fluctuation (starvation) and then run for hundreds of hours before total failure but when they do finally fail it happens quickly and catastrophically. That's a tough one to source inexpensively in another country.
If you can do the work yourself they are a relatively cheap engine to rebuild and not too complicated, you'll also become very familiar with the engine in that case which helps troubleshooting in the future.
Yeah, yeah, yeah, I know, it's a SAILBOAT and I'm sure someone will use that line but if you like having a motor in your boat that runs you'd be wise to make sure it's 100% before running off to places where good mechanics and a ready parts supply will be in short supply.
My current automobile has 320,000 miles on it and still gets 26 MPG, runs fine and uses no oil due to good maintenance, but I'm not driving to the far reaches of the earth with it either, if it breaks down now I can have it towed 10 miles to a dependable mechanic.
Used boat engines are a crapshoot, no matter how good the original manufacturer built them people can and will kill them through negligence.
Depends on how much of an adventure you're looking for.

Very interesting. My boat has a 4-108 and the previous owner put a SS drip pan under the engine. The engine leaks at about the same rate as you described. She is a 1985 engine rated at 51 HP with just under 800 hrs. The clock still works so I assume the hours to be true but who knows. She does smoke black upon startup but clears out when running.

I assume the oil leak is coming from the oil pan gasket. She is dry up top but aside from the pan and the main seal where are other trouble spots?

Btw, I was told by a mechanic just keep her filled and don't worry about the leaks. The 4-108's are like that.

Your thoughts...

BZT

[hellosailor]

Blackstone are probably the leading independent lab. Many engine makers and oil companies have "fleet" programs for their industrial customers, way cheaper than Blackstone's retail price but based on volume.

A baseline and reviewing ongoing changes is the best way to do it, but even that first sample can reveal all sorts of interesting information. First time I used one, it showed a lot of fuel and water contamination. Which just meant "run it hotter and longer, you're not cooking off the normal accumulations". And that's all it took to end the problem, as confirmed by the next test.

Guy-
You can mess around with a can opener all you please but that won't tell you the levels of contaminants or additives in your oil. Chemical analysis can tell you there's a bearing failure to come, or a valve failure to come, well before you are going to break down. A can opener? Won't tell you anything until the engine has already begun chewing itself to bits.

At 10,000 hours most small diesels would be due for their second major overhaul. If it smelled and roses and sounded like Mozart, it would still be time to have a professional examine the engine before embarking on any major plans. Might need nothing. But just based on the hours, it would need an inspection.

[Dockhead]

My father's boat had 9000-something hours showing on the clock when he bought his boat 15 years ago. And the clock was broken . So God knows how many were on it. 15 years later, with very intensive use (he's retired and cruises full time; and motors all the time because the boat doesn't sail worth a d*** ), it's still going strong. I guess he must have put another 5000 hours on it at least; maybe even 10,000. No repairs or maintenance other than frequent and loving oil changes. Spews oil, but they all do that. He never exceeds 2000 RPM; maybe that helps. In any case, they are great, extremely durable engines. Enjoy and don't worry about it.

[model 10]

[QUOTE=hellosailor;1601320].

Guy-
You can mess around with a can opener all you please but that won't tell you the levels of contaminants or additives in your oil. Chemical analysis can tell you there's a bearing failure to come, or a valve failure to come, well before you are going to break down. A can opener? Won't tell you anything until the engine has already begun chewing itself to bits.

That is so absolutely not true. I have cut open a thousand oil filters in 35 years as an aircraft mechanic. I have inspected even more oil screens . You get an excellent idea of how the engine is doing by inspecting an oil filter, less so with most screens.
Oil analysis is great but unless it's a turbine where you can't see anything in the oil screen and the engine is worth a million bucks, it's just more money.
If you don't have a trend an analysis is almost worthless. How long are you going to wait to find out how the engine is doing? 5 minutes with an oil filter and you know immediately.

[boatpoker]

Perkins HT-354-6 I rebuilt it at 20,000 hours even though all it had was a tiny little bit of slap in one piston.
I like things right

[a64pilot]

cutting open a filter, opening the media and washing it out with a solvent, and then filtering the rinse through a coffee filter, inspecting what's in the filter with a magnet and a magnifying glass will tell you more than SOAP will.
This is the cutter I use, it's important that your cutter does not make any metal shavings, a large pipe cutter will work http://www.skygeek.com/ats-afc470.ht...FZJr7AodSy8AXw

I'm with Guy, I've been an A&P/IA for a little while myself, small six cylinder aircraft engines go for about 50K and having one fail is a little more of an issue with an airplane than a boat, hence they are looked after a little more carefully

[boatpoker]

I have done more than a few oil analysis and have formed an opinion

In Oil Analysis. worth the money ? I have included an oil and gear fluid report for those that have not seen one before.

[DumnMad]

Originally Posted by Dockhead

My father's boat had 9000-something hours showing on the clock when he bought his boat 15 years ago. And the clock was broken . So God knows how many were on it. 15 years later, with very intensive use (he's retired and cruises full time; and motors all the time because the boat doesn't sail worth a d*** ), it's still going strong. I guess he must have put another 5000 hours on it at least; maybe even 10,000. No repairs or maintenance other than frequent and loving oil changes. Spews oil, but they all do that. He never exceeds 2000 RPM; maybe that helps. In any case, they are great, extremely durable engines. Enjoy and don't worry about it.

Agree, all depends on frequency of oils changes, whether its short running or long trips, too many cold start-ups and cold running etc. Cummins have a 1 miilion miles club - at an average of 50miles an hour this is 20,000 hours. (Maybe they have oil heaters.)

Cummins High Mileage

[CSY Man]

I assume the oil leak is coming from the oil pan gasket. She is dry up top but aside from the pan and the main seal where are other trouble spots?

Mainly the rear seal on 4-108s.
Very small leaks for the oil pan gasket.
Had one in my boat for 14 years, compression and oil pressure always great.
Would slowly but surely get hot @ high RPMs. (Over 2500)
Found out the more I used the boat, the less oil it would leak.
Probably added 1 quart between oil changes. (100 hrs)
Always used Shell Rotella.
A friend had the same engine in his CSY 37 and had 15,000 hrs on it before overhaul. He said it ran fine, but the hours made him nervous.

[a64pilot]

Originally Posted by DumnMad

Agree, all depends on frequency of oils changes, whether its short running or long trips, too many cold start-ups and cold running etc. Cummins have a 1 miilion miles club - at an average of 50miles an hour this is 20,000 hours. (Maybe they have oil heaters.)

Cummins High Mileage

Block heaters yes, and if like my Duramax there is an oil cooler that is actually more of an oil heater, it's a heat exchanger that has coolant on one side and oil on the so your oil and coolant temps are usually very close to each other.
Also I bet average speed is much closer to 30 mph, making them over 30,000 hours, but I also bet almost all of this is at lower RPM and lightly loaded.
Boat motors and airplane motors are very similar in that usually both are run at constant RPM and relatively hard compared to automotive motors. Age also plays into it of course, my 27 yr old Yanmar had 500 hours on it, but it's not like having a 1 yr old Yanmar with 500 hours

[BZT54]

Originally Posted by CSY Man

Mainly the rear seal on 4-108s.
Very small leaks for the oil pan gasket.
Had one in my boat for 14 years, compression and oil pressure always great.
Would slowly but surely get hot @ high RPMs. (Over 2500)
Found out the more I used the boat, the less oil it would leak.
Probably added 1 quart between oil changes. (100 hrs)
Always used Shell Rotella.
A friend had the same engine in his CSY 37 and had 15,000 hrs on it before overhaul. He said it ran fine, but the hours made him nervous.

Hmm... Main seal. I hardly ever take her over 2000 rpm and she runs cool. I always use Rotella. With the leak being manageable is it worth replacing the seal? Btw, how many hours between oil changes do you recommend on the 4-108.

Thanks for the info.
BZT

[lifeofreilly57]

Yup, the rear main seal is the culprit as well as positive crankcase pressure. On my 4-108 the pan gasket weeps a little but it's a 1987 so I'm sure the gasket is a bit old. I just keep buying more oil mats and changing them regularly, just remember to dispose of them properly. As long as it doesn't get into the bilge.
There's a kit sold that acts as a silencer and air filter for the 4-108 which also acts to produce a slightly negative crankcase pressure which I'm told reduces the amount of leakage from the rear seal. I can't remember the name of the vendor for the life of me but did come across it while researching the 4-108 before buying my present boat. That same kit has been a topic of conversation on this forum as well, in a different section.
Yes, long haul truck diesels do run 20,000 hours between rebuilds but they usually run under the right conditions for engine life, the are started, warmed up (if only to charge the air brake system) and then run at length, which is the best way to get lots of hours out of one. They also have much more engine oil capacity for their size than boat motors. Ever ask about the oil capacity on a big rig? 20 quarts is not unusual. Quick starts and power offs with short run times and shut downs usually produce the shortest engine life, the engine never really warms up completely and is always in a state of dimensional change as the block and internals warm up unevenly, also the oil never really gets warm enough to burn off contaminants or moisture which leads to acids and sludge from condensation mixing with the oil and combustion byproducts.
The diesel in my backhoe is around the same size as the 4-108 in my boat, it has 3 quarts more oil capacity than the boat motor.
My motor is a bit undersized for the boat, which is 47' and 40,000lbs, with the prop and transmission on it I usually run at about 2800 rpm at which the motor runs smoothly.
So, comparing commercial trucks to boats is an apples to oranges comparison, you can't really use that for a guide, it all comes down to how it's used and how it's maintained.
Engine oil analysis is good if done at regular intervals so a history can be plotted, doing it once is a snapshot but doesn't really give you any predictability unless of course it shows a major problem like a failing bearing. This works best on regularly maintained fleet vehicles where regular testing is done.
Cutting an oil filter will show if there's a major failure but isn't as good to trace subtle changes, that's harder to follow, but at least it will tell you if you've got a big problem coming down the pike. Seeing chrome specs in the oil filter folds usually means there's a crank rebuild in your future.
I don't trust in luck when it comes to any type of machinery, if you do it's just a roll of the dice.