# Yanmar 2GM20F How many is too many hours?



## tstewart137 (Oct 4, 2009)

The boat I am looking to purchase (my first) is in overall great shape. This fact makes me feel that the owner probably paid the same attention to the motor as he did to the rest of the boat....However, the motor (a Yanmar 2GM20F) has nearly 2000 hours on it. This seems like a big number to my inexperienced eyes. Is this a red flag of an impending rebuild/replace or is this thing just getting warmed-up?


Thanks!


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## SlowButSteady (Feb 17, 2010)

If it's been well maintained, and if it currently runs well w/o noticeable smoke, I wouldn't think 2000 hours would be "too many" hours. Diesels last a long time; they last a _really_ long time if one takes care of them. It could easily have another ten years left in it. On the other hand, it definitely isn't a new engine. And you probably have no real way of knowing how well the maintenance schedules have been followed. If you'ure really interested in the boat, make an offer subject to a survey. Run a compression check and have the oil analyzed, and/or have a diesel mechanic take a look at it. If the engine is on it's last legs you can renegotiate the sale price or back out of the sale all together.


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## blt2ski (May 5, 2005)

2000 hrs at 50 mph would be a whopping 100K miles of driving. Reality is, 5K to even 10K hrs should be how long a diesel motor will last. If as said, it has smoke even after warming up, hard to start, or worst yet, you need either to start it. it's shot! IIRC I have some 4800 hrs for my pickup motor! no signs of issues. Not sure how many hrs are on my boat, it does not have an hour meter. My trackhoe is 1500, bobcat about 1200........

Marty


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## SloopJonB (Jun 6, 2011)

The average car averages only 25 MPH over the long term. That makes 2500 hours equal to 50,000 miles. My wife's last minivan had almost 300,000 on it and we only got rid of it for cosmetic reasons. That was about 12,000 hours and it was a gas engine, not diesel.

2K hours on a diesel is nothing if the oil has been changed regularly.

Also, keep in mind that the majority of sailboats probably accumulate only around 100 or fewer engine hours per year.


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## SlowButSteady (Feb 17, 2010)

Let me play the "devil's advocate" here for a moment....

Sailboat auxiliaries usually get just about the worst treatment an engine could possibly get. They are most often used for fairly short periods, maybe 10 to 20 minutes, to get the boat out of the harbor and then back to her slip/mooring, OR are left idling for hours to charge even more severely neglected batteries. They are often burning old, dirty fuel. Oil changes get missed/delayed. They live in a corrosive environment, with a corrosive solution splashing all over them at times. Many, like my RWC 2GM20, have that corrosive solution circulating through them, as long as someone remembers to turn on the cooling water seacock. They are often worked on by rank amateurs (like myself), and then get their good names taken in vain whenever they don't perform perfectly. In short, sailboat engine verses car/truck/tractor engine is probably not a very good comparison. That said I still believe that 2000 hours isn't necessarily a huge amount of time on a 2GM20. However, I wouldn't expect most sailboat auxiliaries to last nearly as many hours as a car/truck/tractor engine.


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## rackham the red (Jun 24, 2012)

I agree that a diesel engine has a lot of hours of life. I have two tractors that have over 9,000 hours on the each of the engines and they work just fine and still put out the 100+ horsepower. That being said, I have changed the oil ever 100 hours no matter what because they are in the hot Texas sun pull heavy loads, mowers and balers. I have a Lister Petter engine that has 4500 hours that runs my irrigation pumps, but with the same treatment.

Get a compression test and remove the filter, cut it apart and run a magnet over it. If it has metal filings, it has a problem. My boat has 3000 hours on the Yanmars and still going strong. I changed the head gaskets, but everything else is great. 

I hope this helps. Personally, I am an engineer and a preventative maintenance nut, I don't worry about the hours, I worry about the treatment! 

Rochelle


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## RichH (Jul 10, 2000)

The Yanmar QM and GM series engines will usually reach 10000 operational hours IF, ... big IF ..., proper and normal maintenance is performed. This maintenance can be summed up as simply changing the oil at ~150 hours, retiming the engine (High pressure injector pump) at each 1000-1500 hours, injector inspec/rebuild and intake/exhaust valve lash @ each ~1000-1500 hours; maintenance and replacement of the internal engine and Hx zincs are included ... small marine diesel engines 'rot' away from the inside out. Transmission problems on these engines are a larger problem - change the transmission oil every time you change the engine oil.

All this is predicated on an engine that is matched to the proper prop diameter and pitch so that the engine isnt 'lugging' (excessively high cylinder pressures) due to 'over-propping' (and/or long period of idling which promotes cylinder wall glaze). Engine 'lugging' promotes excess piston wrist pin wear and 'egg shaping' of the cylinder bores.

2000 hours on a Yanmar GM ... the engine is still a 'puppy'.

Dont 'lug' or long term idle the engine, change the oil(s), replace the internal zincs on a routine basis, do a periodic injector inspection/rebuild and engine (injector pump) re-timing; use a 10µM fuel filter preceding the engine mounted 15µM 'guard' filter on the fuel system, etc., etc. 
Use only 'fresh' fuel (dont continually 'top off' the tank) to avoid particle 'growth' in the tankage and to lessen the development of 'coke' in the exhaust system ....... and you will, by average, be seeing *~10,000 engine hours* on these old 'heavy weight' Yanmar engines; they are VERY reliable, long lasting, and 'robust' (knock on wood). Having a Yanmar on a prospective used boat is usually a BIG plus.

BTW - an easy approximate method to check to see if the engine is not 'lugging' - 'cruising rpm' should be 75-80% of max. engine rpm.

FWIW - If this boat had a Volvo engine ... Id run away, as even the simple 'usual' replacement parts costs will far exceed the price of a brand new Volvo or replacement engine. ;-)


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## jrd22 (Nov 14, 2000)

As others have said the hours aren't necessarily the most important part of evaluating an engine. One of the most important things to check is whether it is correctly propped. If the engine can't reach full rated rpm when underway (assuming clean prop and bottom) then it is lugging the engine at all rpms and you can expect a short life. On the other hand, just the age of the engine is a factor to consider since there are components that "wear out" just from exposure to salt water (heat exchanger, oil cooler, etc). If the engine starts well when cold without excessive blue smoke, runs clean and doesn't overheat at full rpm underway (5 minutes min.) and appears to have been taken care of 2000 hours isn't a concern IMO.

Edit: Ha! Rich beat me to it, and with more detail to boot.


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## rackham the red (Jun 24, 2012)

A couple of things I can add to Rich and John's excellent discussion is the following:

When getting you injection pumps timed, send them out to a diesel farm service. That will save you hundreds of dollars. For example, the marina quoted me 1300 dollars per injector. You can remove them your self, but mark on the frame and the pump so the gears are in the same location when re-installing. (for timing) Then send it to a tractor dealer and pay $600 for the same service.
Also I use John Deer diesel additive, in every tank of fuel! There are lots of diesel additives but this one really works. It also keeps the diesel from gelling and keeps any microbes and algae from growing. This product also lubricates the injectors. I also use Lucas injector cleaner every 4th tankful. 

Just a thought for your consideration
Rochelle


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## rrroger (Oct 29, 2016)

Diesel engines in most recreational vessels seldom wear out - due to the normally small amount of use they get -they usually corrode and face other such problems...so age may be generally be a bigger factor than usage...Providing it is correctly propped...and the maintenance has been regularly done...all should be well...PROVIDING...! (If!!)


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## capecodda (Oct 6, 2009)

When the wind dies, we are running a powerboat with a 6YL 315 HP Yanmar engine with over 5000 hours. We take it offshore fishing, single engine, where it would be a long tow back. No sails as backup. I've had one problem, just recently, we replaced an oil line that lubricated the injector pump because it was looking a bit ragged, and the NEW oil line failed. The old stuff is doing fine. I think one reason this boat is doing so well is it gets lots of use. 300-500 hours/year, and it gets 100 hour oil changes religiously. If we ever see any fluid leak, even a drop, we fix it. 

On sailboats, I've had Westerbekes, Yanmar, and Volvo's. The Yanmars have been trouble free. What you don't want to do is overheat them. They don't like that. If that engine was taken care of, as RichH is suggesting, it may outlive you. IMHO I wouldn't consider 2K hours on a well cared for Yanmar even the slightest impediment to a purchase. In fact, there's a good argument that a somewhat used engine is more trustworthy than a new one. I've had friends with new engines have early life failures.

When buying a used diesel, I'd recommend planning on having a mechanic check everyplace salt water flows after purchase. In that engine, I think that would be simply a heat exchanger, raw water pump, and exhaust elbow. Maybe an oil cooler. If that stuff need to be cleaned up, it wouldn't cost much and save problems down the line. Salt is tough on stuff. If it's running well I wouldn't consider these survey items....just normal maintenance and establishing a baseline.

Buy the boat and get going . Good luck.


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## JimsCAL (May 23, 2007)

Four year old thread. I think he probably made his mind up one way or the other.


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## RobGallagher (Aug 22, 2001)

JimsCAL said:


> Four year old thread. I think he probably made his mind up one way or the other.


Happy Easter!


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## Giarc (Jul 13, 2021)

tstewart137 said:


> The boat I am looking to purchase (my first) is in overall great shape. This fact makes me feel that the owner probably paid the same attention to the motor as he did to the rest of the boat....However, the motor (a Yanmar 2GM20F) has nearly 2000 hours on it. This seems like a big number to my inexperienced eyes. Is this a red flag of an impending rebuild/replace or is this thing just getting warmed-up?
> 
> Thanks!


This is a alittle late response, diesels should last 10k hours, but for some reason 15k hrs is the mark.


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