Cummins Diesel
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A little bit more specific questions would help us help you. I have 330hp Cummins in my boat. I do think they are generally the same engine. The difference in power is that the aftercoolers on the 270hp version are cooled by engine coolant. Whereas as mine are cooled by seawater. I am not going to assume you know everything about internal combustion engines.... So, the cooler the charge air, the more power it produces. Seawater cooling provides a significantly cooler air charge. Obviously, a leaking aftercooler is less disastrous when it is coolant that is going into the intake instead of seawater. Also, there is an immediate symptom when coolant is being burned....billowing white smoke and the sweet smell of burning anti-freeze. Saltwater intrusion from a leaking seawater aftercooler can go unchecked and usually causes a slow an insidious death of the engine.
Blah blah blah. The 210/220hp versions of this engine have no aftercooler.
They are good motors. The higher horsepower versions need to be more closely "monitored" because you are asking a lot of a 5.9 liter engine. Parts are (relatively)cheap and can be found anywhere.
The Sherwood raw water pumps on these motors are not very well thought of and replacements can be found on the aftermarket for half the price for a better pump.
Tony Athens on boatdiesel.com is the accepted guru on these motors. He is extremely knowledgeable. He is also seller of those aftermarket parts. He believes that most of the ancillary accessories on these motors are not very well engineered and he has hence, re-engineered those accessories. I guess I am just warning you if you decide to join over there. It is all doom and gloom...people with problems.
If I were buying a boat that was not going to plane, I would go with the 210/220hp engine as they have no aftercooler. Aftercoolers and their maintenance can be expensive and a pain in the butt. A somewhat knowledgeable owner will service their aftercoolers every 2-4 years to the tune of about a 1 boat buck if you have someone else do it. "Cheap" insurance for the health of your engine but not necessarily cheap. Most owners aren't that knowledgeable. My boat is 12 years old. POs had never serviced aftercoolers. Luckily they were okay.
I do not know if the 210/220hp versions have fuel coolers....but I doubt it. That is another cheap part that can cause significant damage if they fail....which mine did. Fouled 2 injectors and filled my starboard fuel tank up with seawater which founds it way into the engine(a racor can only do so much with that much seawater). Again, cooler fuel contributes to a cooler fuel/air charge....equals more power. That is why I am assuming the 210/220hp engines do not have fuel coolers. Check for yourself.....but that is another vote for the lower powered ones if you do not need the power.
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Steve
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I have a 2003 Monk 36 with the 220 HP diesel there were several boats made with the 270 hp Cummins. I have never heard any complaint about them by owners on the Monk Owners forum. I don't think it will make much difference as far as fuel consumption, I am quite sure the boat will not plane with it so you will probably run it at the usual cruising speed of a trawler around 7 knots anyway. Maybe run it at high rpm a few minutes once in a while if you are concerned about underloading. My experience with the Sherwood pump has been good, I change impellers every year or 150-200 hrs, I did buy a new Sherwood last year and installed it, and kept the original 2003 for a spare.
Feel free to Private Message me if you have any questions about the Monk 36
Feel free to Private Message me if you have any questions about the Monk 36
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Correct. The 6B engines are 5.9 liter diesel; the variants are all based on the same block, the same block that roams the streets in millions of Dodge pickups. The differences are
- Naturally aspirated
- Turbo
- Turbo aftercooled (fresh water)
- Turbo aftercooled (raw water)
As the HP goes up, there are changes in the injector pump/timing, compression, cam profile, charge air cooing system, and turbo.
The best engines IMO are the 250/270 variants- great power, and not too much stress on the engine. The Diamond Series (330-370 hp) are great engines, but have been more prone to problems than the 250/270 HP engines.
It'd be hard to go wrong with a Cummins.
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I think comparing these engines and their reliability to a Dodge truck can be misleading. The truck versions are hardly ever asked to do the work that marine versions are asked to do. Dodge trucks just aren't subject to the loads that boats are subject to. And the chances of a Dodge truck ingesting seawater from a faulty aftercooler are just about nil...
I will reiterate. If you can avoid the versions with the aftercoolers and/or fuel coolers, I would do just that if the extra power is not needed. Those are things that need to be maintained and things that can really ruin your day if they fail.
I will reiterate. If you can avoid the versions with the aftercoolers and/or fuel coolers, I would do just that if the extra power is not needed. Those are things that need to be maintained and things that can really ruin your day if they fail.
HopCar
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"The Sherwood raw water pumps on these motors are not very well thought of and replacements can be found on the aftermarket for half the price for a better pump."
Do you know of one that allows you to change the impeller without removing the hoses? That's the only thing I don't like about the Sherwood.
"The Sherwood raw water pumps on these motors are not very well thought of and replacements can be found on the aftermarket for half the price for a better pump."
Do you know of one that allows you to change the impeller without removing the hoses? That's the only thing I don't like about the Sherwood.
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The only replacement I am aware of is this:
SMX Seawater Pumps for Cummins Marine Diesel Engines
I think it depends on your installation as to how easy it is to service the impeller.
And for anyone reading this that wants to learn a bit more about Cummins engines, check out this link.
Tony's Tips - Information about Marine Diesel Engines and Boats
There is tons of info in there.
sunchaser
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As other posters have noted, the 270 has an after cooler whereas the 220 does not. As a survivor of a failed after cooler, anything you can do to avoid them is worth extra money IMHO.
You would never use the 50 HP the 270 has anyway in a Monk 36. But at the end of the day, go for the boat in the best condition and if the 270, perform after cooler service (not necessarily easy) per boatdiesel.com.
Both are good engines and the Sherwood RW pumps are easily replaced by better ones if yours is problematic.
BruceK
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Right on. Boats hardly ever coast downhill at idle.
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On my Bayliner 4087 with twin 6BTA 250hp engines, I was able to change the impellers by simply taking off the rear covers and twisting them out.
The pumps were OEM.
Re: post #5 above: fuel coolers are very easily removed by an owner. They are not generally needed in trawler-style vessels with relatively large fuel tanks which readily dissipate heat. They are a failure point you do not need to live with
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Tony Athens agrees with you and I would agree to an extent. If you read his article in that link I posted you will see. Since he is a certified Cummins dealer, I don't think he can come out and say to remove them. But you can read between the lines. Just be careful what you call "trawler-style". It has nothing to do with the "style" of boat but if you fuel tanks are not that big AND you run on plane(ie cycling a lot of fuel) AND you live on hot climes, then it could be argued you should leave them in place. If you are running around at 1500RPMs all the time, then no, you shouldn't need fuel coolers. My fuel tanks are small...108 gallons x 3...I run on plane regularly...and I live in Texas. Before I even start the engines, fuel temp could be well above 100 degrees in the Summer. My compromise will be to change them every 2 years. They are fairly cheap. And always check what is in the Racor bowl before, during and after you run the boat.
http://www.sbmar.com/articles/understanding_marine_fuel_coolers/
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jleonard
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The aftercooler on the 270 Diamond is anti freeze cooled and requires no maintenance. It won't fail like a sea water aftercooler will. This aftercooler is also nice in that you can run at low rpms and not worry about lowering the cylinder temps like a sea water unit will.
I say go for the HP, you won't regret it.
RickB
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I don't know why anyone would worry about lowering the cylinder temps because of a seawater cooled aftercooler.
Consider that charge air temperature in a normally aspirated engine is around 100F plus or minus, depending on ambient conditions. At the point of fuel injection, air in the cylinder is around 1000 or higher.
A turbocharged engine at low power will deliver charge air out of the turbo at around 200F or less, a seawater cooled aftercooler might bring that down to around 125 or so. At worst the temperature of the air entering the cylinder will be about the same as a naturally aspirated engine.
Overcooling charge air will reduce smoke at all loads but the downside is it may produce a substantial amount of condensation in high humidity conditions. That water may damage the aftercooler, the piping, the valves, cylinder wall, and rings. Those problems are more likely to occur at high power as the temperature difference across the cooler is greater and a greater weight of water per unit of air volume is present.
The other side of that is high humidity is normally associated with high sea temps as well so there won't be a great deal of condensation at low loads and low boost pressure in cooler seas.
Those who are desperate to worry about something can easily find another more likely threat, like being rammed by a whale or something.
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HopCar
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"On my Bayliner 4087 with twin 6BTA 250hp engines, I was able to change the impellers by simply taking off the rear covers and twisting them out."
My engine is a 6BT not after cooled. There is no cover on the Sherwood pump. You have to remove the whole pump housing to get at the impeller. It's a terrible design.
My engine is a 6BT not after cooled. There is no cover on the Sherwood pump. You have to remove the whole pump housing to get at the impeller. It's a terrible design.
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Jay
I believe you meant low, not no maintenance. Everything on the coolant side requires maintenance especially HXs whether air or liquid. Even coolant pumps give out.
Are not the O ring seals on the after cooler subject to the same deterioration whether salt water or coolant is use? I agree the metal parts should last longer, how much is a question because you still have charge air on one side that is not always pristine. Most engine manufacturers remain silent (stupid) on book related after cooler maintenance. At a minimum, a coolant cooled after cooler will require the same servicing interval as the HXs.
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Thank you!!! You beat me to it!!!
jleonard
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Right. About as much as a car radiator which isn't much. They last 20 years in busses according to a couple of bus mechanics I know.
sunchaser
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My history with JWAC off road engines goes back 45 years. All require maintenance much more frequently than 20 years. Coolant losses into the cylinders are watched like a hawk especially with engines under warranty. With turbo boost potentially above rad fluid pressure, problems can go both ways in a, say, Cat haul truck.
The key to this discussion though is after coolers are not the mariners best friend and if you can avoid them in our toy boats you are better off.
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The 270hp version is quite common....not sure about the 280hp version.
C lectric
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There is all kinds of confusion about HP ratings. Part of it is newer models. It still called a 6bt or 6bta but Cummins adds a bit of hp over the years.
Also there are two ratings they use , METRIC HP AND SAE HP. and the number is different for what is the SAME engine and the same power output. There are other ratings to boot. It's no wonder people get confused. It's not as bad as the car mfgrs. but it's still confusing at times unless you also know which rating they are referring to.
Of course Cummins is not the only mfgr to play this game.
Also there are two ratings they use , METRIC HP AND SAE HP. and the number is different for what is the SAME engine and the same power output. There are other ratings to boot. It's no wonder people get confused. It's not as bad as the car mfgrs. but it's still confusing at times unless you also know which rating they are referring to.
Of course Cummins is not the only mfgr to play this game.
jonboat26287
Newbie
First picture by Xsbank is a 6CTA 8.3M1 JWAC engine from the early-mid 90's. Usually known as a "300C" although they did sell some rated at 250HP. Very solid engine never asking for much.
As to the genuine Cummins marine 6BTA 5.9's that were JWAC, Cummins released not less than 5 versions of them. The first versions ( 1988-ish) used the CAV fuel injection system (CPL953 & 1247 most popular in the USA).. Later, they released at least 2 versions using the ND EP9 fuel system (CPL1570 & 1322). Later, they released the 260 /270 version using the Bosch P7100 injection pump.
A caveat to these motors that many don't know is that Cummis de-rated some to an MCD rating in the 220 HP range ( a tweak in the injection pump) but share the same CPL.
Cummins RECON still makes 1 or 2 versions of the engine although they charge more for a JWAC 260/270 than they do for a 6BTA SWAC 370 Diamond.
JB
As to the genuine Cummins marine 6BTA 5.9's that were JWAC, Cummins released not less than 5 versions of them. The first versions ( 1988-ish) used the CAV fuel injection system (CPL953 & 1247 most popular in the USA).. Later, they released at least 2 versions using the ND EP9 fuel system (CPL1570 & 1322). Later, they released the 260 /270 version using the Bosch P7100 injection pump.
A caveat to these motors that many don't know is that Cummis de-rated some to an MCD rating in the 220 HP range ( a tweak in the injection pump) but share the same CPL.
Cummins RECON still makes 1 or 2 versions of the engine although they charge more for a JWAC 260/270 than they do for a 6BTA SWAC 370 Diamond.
JB
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