How many hours are too many?

42' motor yacht with twin Cat 375hp engines that have 5000 hours over 30 years. Is that too much to consider? If I put another 2000 hours on these engines over 5-7 years will that decrease the value on selling the boat?
On the other hand what about a 20 year old boat with less than 500 hours? Would that be too few hours even if it was run on a regular basis?

It depends entirely how well the engines have been looked after. There are diesels that have 20000 hours on them, have been looked after, and are still running well.
Fortunately telling how good the engines are is reasonably quantitative. All you have to do is have a good mechanic survey them.

Brett

I am in the same camp as Brett.

Have Caterpillar do a survey/consultation for you. MUCH additional data is needed to answer your question such the engine model, configuration, maintenance history, type/frequency of use, and possibly some oil analysis.

For example, if my current engine (VP D4-260) had 5000 hours, it would be a substantial consideration. Those hours are not concerning for a Ford Lehman 120 or a Lugger in a trawler or passagemaker.

Good Luck

IMO another 2000 hours won't change much. At 5000 or 7000 hours most buyers will want pricing that assumes a rebuild. cat formerly advised 30,000 gallons of fuel to rebuild.
The problem with hours is that it doesn't tell much about wear. Work done is the primary issue other than marine age. If the engines were run at low load there will be less wear than if the were run 200 off the top. Unfortunately we have no way to tell without opening the engines.

There is no such thing as too many hours.

Unless you started boating at 17 and your 78 now and you've been accumulating hours at a much higher rate than average. I've heard of engines going 15 to 30,000 hrs so placing importance on hours accumulated seems silly to me.

Engines die (or get their lives for-shortened) from carelessness, accidents and neglect. And over an engine's life lots of opportunities for misuse occurs w various owners. And one could say a high number of hours accumulated is a good sign as the probability that the engine was well taken care of speaks for itself .. If the engine has good compression ect.

No such thing as too many hours. However in a controlled environment like a heated room for a stationary engine always 100% preheated before starting ect ect and many engines run this way could establish a maximum number of hours that can be accumulated on a given engine. But none of these engines will be found in a pleasureboat. So no such thing as too many hours.

IMO the function of an hour meter is to schedule maintenance on properly and regularly run engines. So, as others have said, it comes down to care and operation of the engine, not numbers on the hour meter. Get a survey by a mechanic familiar with the engine(s) in the boat.

The work boat I ran has 2 gens. I supervised the installation and managed the maintenance. Both have been run at moderate loads and properly maintained. As of 3 yrs ago when I stepped off the boat Gen #1 had 22,000 + hrs, Gen #2 had 18,000 + hrs. Both are Isuzu 4BD1. They have required in addition to maintenance some minor repairs. Water pump, thermostat, injectors. Both are still running strong.

The main is a Cat D379. When we acquired the boat the hour meter was broken showing about 8,000 hrs. We have no idea the real hours but it was in bad shape requiring an in frame overhaul. The hour meter 3 yrs ago showed 27,000 + hrs. Due likely to poor care by the previous owner / operator the main has required regular repairs to keep her running.

Portage Bay,
Those Isuzu engines are great.

the above misses the point. Low load engines dont wear out high load engines do. The OP asked about 3208s rated at 375 HP. That is far from low load rating. BUT if they were run at 100 HP they would last forever.

bayview said:

the above misses the point. Low load engines dont wear out high load engines do. The OP asked about 3208s rated at 375 HP. That is far from low load rating. BUT if they were run at 100 HP they would last forever.

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Based on what baywiew?
Mechanical forces? Temperature? Cycles?
Because the piston is offset from the crank there are side forces on the piston to cylinder interface perhaps 15 to 20% of the downforce on the piston crown. A very considerable force that I've not heard mentioned here on TF.
Or perhaps you are thinking of other forces.

Your thinking throws out the fuel burned philosophy. Some think it's cylces .. start run stop start ......


I'm thinking it has a lot to do w many factors. But if the condition of an engine can be determined why worry or even think about the number of hours on the meter?
I've thought that true of cars. Check out an engine via all the means available and agree w the findings. Same probably applies to boat engines. If not what am I missing?

When it takes 1/2 a can of ether to start the engine in 70 deg temps,
or it blows white smoke even when at operating temperature ,
or you burn too much lube oil per hour to afford, the engine is ready for some love.

A very low time engine would scare me more (500 hours vs 5000 in 30 years).

Cylinders can rust when not in use , which re oils them, so pitting in the cylinders can lower compression or hold oil that will simply burn.

Larger truck or industrial engines can be given an inframe , lifted and cylinders and beatings replaced.

Boat Hours and oil analysis

There are too many unknowns with engines. How often were they run, at what load, were they maintained properly, etc. You can get a oil analysis that will help but you need at least 50 hours 100 would be better. It helps to know the oil brand what if any additives were added and how much oil was added. They check how much soot, different metals, and other things are in the oil. That will help you determine the condition of the engine. But like other have pointed out hours are not a good indication on the condition of the engine. I recently purchased a 31 year old boat with 1750 hours on it. The oil and filter had just been changed. I ran it at light to moderate loads (up to 2/3 of WOT RPM) for 82 hours and then pulled a oil sample.. My boat was over propped by 4" (24" factory was 20" both are 24" diameter) so WOT was only 2100 RPM most of the running was at 1200 rpm. The analysis came back with very low levels of all contaminants. The analysis company rated the engine a 1 on a scale of 0 to 5. I didn't have to add any oil over the 82 hours (the level did drop about 1/2 to 1 qt) The engine is a 135 Ford Lehmann. If you have any other questions about the oil analysis please let me know. It only cost $30.00 and I received the results within 2 weeks of sending in the sample (US Mail). The company I used was Horizon and I purchased the analysis through Boat US. You get a US Post Office approved shipping container and a prepaid mailing address label. Again if you have any questions let me know. I'll try to attach the file but if it doesn't get attached and you would like to see it send me a private message with your e-mail. The 2 yellow highlighted numbers are because I didn't know what oil additives the previous owner had added they are not because their is a problem with the engine.

Eric: Yes piston side forces and other forces causing cylinder wear but there are many other items that wear. All lubed parts wear. Engines do wear out. If not work done what else do you think causes them to wear?

" If not work done what else do you think causes them to wear?"

I am not sure I have ever come across a trawler with an engine that is actually worn out.

Killed in many ways for sure , changed with low time , you bet , but worn out? not yet.

The sailboat engines 4-107 et all do get worn out as many idle "forever" with only a tiny load to create juice for a fridge.

bayview said:

Eric: Yes piston side forces and other forces causing cylinder wear but there are many other items that wear. All lubed parts wear. Engines do wear out. If not work done what else do you think causes them to wear?

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bayview,
They say oil is to keep metal parts from touching. I wonder how wear happens if they don't touch?

You ask what causes them to wear out? That's what I'm trying to get you to tell me. A little goading at least got your attention. But I've never heard anyone say what actually causes the wear. Never mind the start up w no oil pressure song either. Searching for the real answer.

Well eric years ago I got into a lot of engines and saw cylinders worn out of round and spec. bearings worn, gears wrorn. Oil provides an excellent cushion to keep metal parts apart but it must not be perfect otherwise nothing would wear.

race engines are rebuilt often because they are doing a lot of work, high loads on the lubed surfaces as well as high temperatures.

Those little sailboat engines running at 20 HP per liter will not ever wear but a big Cat at 50 or more HP per liter is a different story. Run that same engine at 20 hp it wont wear either.

It has little to do with who made the engine much more to do with how high it was loaded