Air or water cooled engine?

[Arthur Brown]

Looking at a boat I had to note that it was an air cooled engine, What are the pros and cons when compared to a water cooled engine.

 

I can still get electricity from it, but I presume I have to throw that heat away and buy cabin (and water) heat separately.

[alan_fincher]

Yes,

 

Downsides of air cooled:-

 

Can't heat domestic water with it

Potentially nosier.

 

Advantages:-

 

No water circuit to worry about or leak - no freezing up - no skin tank - no raw water inlet.

[Paul C]

Our boat also runs central heating (radiators) from the engine coolant, so you could add that to the list of disadvantages of air cooled. And the advantages of no raw water inlet and no freezing up are easily solved by using a keel cooled engine with appropriate antifreeze in the system, leaving only the fact that there's coolant, and a skin tank, as the downsides.

 

In fact I'm not sure what the problems of having a skin tank are?

[Naughty Cal]

Overheating if not sized correctly.

[Paul C]

Overheating if not sized correctly.

 

So, if its sized correctly.......there is no other problem?

[alan_fincher]

Our boat also runs central heating (radiators) from the engine coolant, so you could add that to the list of disadvantages of air cooled. And the advantages of no raw water inlet and no freezing up are easily solved by using a keel cooled engine with appropriate antifreeze in the system, leaving only the fact that there's coolant, and a skin tank, as the downsides.

 

In fact I'm not sure what the problems of having a skin tank are?

Well received wisdom is you should be changing the coolant every few years, because even if the anti-freeze mix is still offering frost protection, the corrosion protection gets lost over time. Responsible disposal of the old coolant is often problematic.

 

I admit it depends a bit on the water cooled engine, but if like me you have a marinised vehicle or industrial engine with one of those great big rubber domed connections at one end of the Bowman or Polaris header tank, then you avoid them ballooning up over time, and splitting at the least convenient time possible. (Plus they are £30 plus each time they need replacing).

 

With an air cooled engine like a Lister, if your fan belt breaks when you are on the tidal Thames, the worst that happens is that your alternator stops charging, but you will not overheat. With a water cooled engine you would quickly be in trouble.

[andywatson]

 

With an air cooled engine like a Lister, if your fan belt breaks when you are on the tidal Thames, the worst that happens is that your alternator stops charging, but you will not overheat. With a water cooled engine you would quickly be in trouble.

Not with a Gardner LW. The water pump is mechanically driven.

[BEngo]

Not with a Lister JP or SW (water cooled SR) or with a Kelvin J or K. All have mechanical drive to the water pump. Not sure about the Lister HRW, the HAW/HBW or FR or the various Rustons. As for Bolinders, up to and including the key-start ones, Seffles and Kromhout semis, or even the Industries, I don't know.

 

N

[MoominPapa]

Not with a Lister JP or SW (water cooled SR) or with a Kelvin J or K. All have mechanical drive to the water pump. Not sure about the Lister HRW, the HAW/HBW or FR or the various Rustons. As for Bolinders, up to and including the key-start ones, Seffles and Kromhout semis, or even the Industries, I don't know.

 

N

FR water pump is gear driven. On engines with raw water cooling and water/water heat exchangers, both the fresh and raw water pumps are gear driven.

 

MP.

[Neil2]

With an air cooled engine like a Lister, if your fan belt breaks when you are on the tidal Thames, the worst that happens is that your alternator stops charging, but you will not overheat. With a water cooled engine you would quickly be in trouble.

Not with a (keel cooled) Bukh either!

[Lockie Junior]

My two pennorth:

 

Air cooled is simple (no cooling to worry about), but can be (very) noisy. Also if in a narrowboat then there may be a ventilating slot cut in the side, not so good if you plan to go out on the Thames...

 

Water cooled is quieter and smoother due to the water jacket acting as sound insulation. However the cooling system is more complicated and can fail (usually at the most inconvenient time, as mentioned above). It also creates an extra hole through the hull, so make sure you can shut off the seacock in a hurry. If its of the suck, swirl and spit (direct/indirect as opposed to keel) type of water cooling then that can block up with plastic bags, etc.

 

Personally I prefer air cooled because of the simplicity, but thats a personal choice to be made by the OP.

 

Also if you really want free hot water from an air cooled engine then you could get a tank made to fit round the hot exhaust pipe.

 

Regards,

Lockie.

Edited March 27, 2014 by Lockie Junior

[Naughty Cal]

FR water pump is gear driven. On engines with raw water cooling and water/water heat exchangers, both the fresh and raw water pumps are gear driven.

 

MP.

 

Ours isnt!

 

The "fresh" water side is gear driven, the raw water side is belt driven. Of the four belts on the engine this is the only one that would cause a problem if it snapped. We could manage without the power steering belt, alternator belt or super charger belt but the water pump belt would very quickly stop us

[alan_fincher]

Sounds like your modern turbocharged monster is not as well though out as many of the vintage chuggers that people have listed with a gear driven pump then

 

I didn't realise so many avoided use of a belt, so I have learnt something there.

 

Most modern ones do, I think, and to me it is one of the bigger worries of taking a normally canal going narrowboat out on a tidal river like the Thames. One hears of people with failed belts taken under tow by an accompanying boat, but both times I have done it in our boat, there has been nobody with us who could rescue us if we did have to stop running the engine

[Naughty Cal]

Sounds like your modern turbocharged monster is not as well though out as many of the vintage chuggers that people have listed with a gear driven pump then

 

I didn't realise so many avoided use of a belt, so I have learnt something there.

 

Most modern ones do, I think, and to me it is one of the bigger worries of taking a normally canal going narrowboat out on a tidal river like the Thames. One hears of people with failed belts taken under tow by an accompanying boat, but both times I have done it in our boat, there has been nobody with us who could rescue us if we did have to stop running the engine

 

We usually have one of these not too far away if all else fails

 

 

Im sure VP had their reasons for making the raw water pump belt driven. What it is I dont know but someone somewhere must

[alan_fincher]

I'm never confident that one of those would turn up fast enough if I put out a distress call on the Thames.

 

It doesn't seem to me it would be long before I was pinned against some bridge, pier or massive trip boat or barge, (if you accept the suggestion that the typical anchor that us narrow boaters carry probably isn't going to actually work on that bit of river!)

[Naughty Cal]

I'm never confident that one of those would turn up fast enough if I put out a distress call on the Thames.

 

It doesn't seem to me it would be long before I was pinned against some bridge, pier or massive trip boat or barge, (if you accept the suggestion that the typical anchor that us narrow boaters carry probably isn't going to actually work on that bit of river!)

Well you aint going to go too far if you end up pinned against a bridge. Plenty of time to get the kettle on whilst the cavalry arrive..............

[Tony Brooks]

 

We usually have one of these not too far away if all else fails

 

 

Im sure VP had their reasons for making the raw water pump belt driven. What it is I dont know but someone somewhere must

 

Modernish truck engines have no easy facility to drive a pump mechanically? Cheaper than the castings and machining needed to fit an engine mounted pump on a modernish truck engine?

[Phoenix_V]

It doesn't seem to me it would be long before I was pinned against some bridge, pier or massive trip boat or barge, (if you accept the suggestion that the typical anchor that us narrow boaters carry probably isn't going to actually work on that bit of river!)

 

Like this you mean? http://riverthames.sosugary.com/displayimage.php?pid=916

[luctor et emergo]

 

Ours isnt!

 

The "fresh" water side is gear driven, the raw water side is belt driven. Of the four belts on the engine this is the only one that would cause a problem if it snapped. We could manage without the power steering belt, alternator belt or super charger belt but the water pump belt would very quickly stop us

Power steering? On a cruiser?

What ever next, ABS brakes??

[Paul C]

Power steering? Turbocharged Volvo Penta? Tidal rivers? I think we've lost sight of things here, when we're talking about a canal boat on a canal. If the water pump belt goes, the engine isn't going to suddenly boil, you've got enough time to get to the towpath, and even if not, then shutting off the engine is going to let you drift to safety in 99% of situations. And, proper servicing including inspecting the belt at regular intervals means a snapped belt is VERY unlikely anyway. So pragmatically, there's no disadvantage associated with the belt driven coolant pump setup.

[Naughty Cal]

Power steering? On a cruiser?

What ever next, ABS brakes??

To be honest it is overkill on ours the steering isn't heavy but on some of the twin engined boats it is a god send. Unless you like a workout!

[Neil2]

I'd be interested to know from those with more engineering expertise what determines whether an engine is designed with a gear or belt driven water pump.

 

I guess my Bukh has a gear driven pump because it's really a sea boat engine and gears are more reliable that belts, but it seems to me that it's easier/cheaper to just bolt on a pump with a pulley so is it just cost..?

 

As for the original question, despite the disadvantages there is something to be said for keeping things simple on a boat which is why there will always be a market for air cooled engines. I wouldn't even consider the water heating angle, the only real disadvantage is the noise but even that is a subjective thing and many Lister owners wouldn't have it any other way.

[cereal tiller]

I'd be interested to know from those with more engineering expertise what determines whether an engine is designed with a gear or belt driven water pump.

 

I guess my Bukh has a gear driven pump because it's really a sea boat engine and gears are more reliable that belts, but it seems to me that it's easier/cheaper to just bolt on a pump with a pulley so is it just cost..?

 

As for the original question, despite the disadvantages there is something to be said for keeping things simple on a boat which is why there will always be a market for air cooled engines. I wouldn't even consider the water heating angle, the only real disadvantage is the noise but even that is a subjective thing and many Lister owners wouldn't have it any other way.

Just a matter of production cost

 

Belt drive allows extra components to be fitted fairly easily

 

CT

[OldGoat]

Put it simplistically, would you prefer driving a Citroen deux chevaux (air cooled)

OR a Volvo (won't say a BMW)

 

It's that sort of difference-

Air cooled units are noisy (nosier)

generally underpowered

awkward to adapt for large alternators

No way to hear hot water or other creature comforts.

 

If your view of boating (or just living) needs some modern comforts then an aircooled engine is not for you.

 

If you wear hair shirts or are happy in a minimalized camping environment - then on a cost basis an air cooled lump would suit.

Consider an Armstrong Siddeley.

 

 

 

[alan_fincher]

It's that sort of difference-

Air cooled units are noisy (nosier)

generally underpowered

awkward to adapt for large alternators

No way to hear hot water or other creature comforts.

Ours very most certainly isn't!

 

There is no problem in finding air-cooled engines suitably powerful, (or too powerful!) for canal boats, is there?

I think we've lost sight of things here, when we're talking about a canal boat on a canal. If the water pump belt goes, the engine isn't going to suddenly boil, you've got enough time to get to the towpath, and even if not, then shutting off the engine is going to let you drift to safety in 99% of situations. And, proper servicing including inspecting the belt at regular intervals means a snapped belt is VERY unlikely anyway. So pragmatically, there's no disadvantage associated with the belt driven coolant pump setup.

Quite a few of us do take canal boats on tidal rivers, though, so we have only "lost sight of things" if the OP can state categorically that they never will.

 

If you don't ever put yourself in that situation, then that's fine, but I certainly recall at least one member on here lost a belt on the Thames, and I'm fairly confident they thought they had checked it over before setting off.

 

That is not one of the "99% of situations" where you can "drift to safety". I admit such failures are uncommon, but they do happen.