View Full Version : Air cooled vs. Liquid cooled

06-29-2001, 11:34 AM
Can someone tell me what the differences are between an air cooled and a liquid cooled engine?

Which is better, and why?

Kent Lawns
06-29-2001, 12:26 PM
In a Nutshell:

Fact 1. Liquid carries the heat away much more quickly than air.
Liquid cooled engines run cooler.

Fact 2. Metal expands with heat.
Liquid cooled engines need much less room to allow for expansion.
They can be made with much closer tolerances resulting in better quality and lower fuel consumtion.

There are a number of other contributing factors as well.

06-30-2001, 11:00 AM
Thanks Kent,

John DiMartino
06-30-2001, 12:27 PM
A few other things also,usually L/C engines of the same displacement will make about 10-20% more power,while lasting 2-4 times longer.The oil in the air cooled engines works very hard and requires more frequent changes due to its very high operating temps,it also cools quite a bit too.This is why deluxe Dixie choppers with kohler's last so long,the oil is cooled by an extra cooler,dropping temp the average oil temp about 20 degrres,this combined with the 1 micron amsoil filter which is 99% efficient at 3 Microns.Together they will double the life of the air cooled engine,letting it last almost as long as an L/C motor.The biggest problem with L/C turf equipment is poor maintaince of the radiator screen.The radiator and screen must be cleaned regularly.The fins,and shrouds od air cooled mowers should also be kept clean,but few even check them,until its too late.

Kent Lawns
06-30-2001, 06:50 PM
That's a good point.

That's why Eric has a gizillion hours on a A/C Kohler and nobody else has.

The oil also gets dirtier from combustion than L/C oil does.

It would be my bet that Synthetic oil would be quite beneficial in an A/C engine, especially in the South.

06-30-2001, 07:02 PM
you fellas make it sound like if you could put a exstra 2 qt
resevoir on a air cooled you would exstend the life of the engine.
is this already available that would fit a kohler command 20.

Eric ELM
06-30-2001, 07:54 PM
Originally posted by Kent Lawns
That's why Eric has a gizillion hours on a A/C Kohler and nobody else has.

I am not the only one, Bill Parish (Fine Lines Lawn) has a Chopper with over 3,500 hours on it, but I can't catch up to him. :)
It is also a 22 HP Kohler, which is the best gas engine I have owned. Mine should hit 3,500 this week, if we have any grass to mow. Man did it turn dry here in a short time. We went from rain every day to brown grass in the shortest time I've ever seen. :(

Kent Lawns
07-01-2001, 01:23 AM
What I'm saying is: I think that oil-cooling system Dixie has explains why you (Plural; all DC users) are getting the number of hours on those machines.

It makes perfect sense, because without the cooling system, it just doesn't happen, even with the care you give your equipment.

John DiMartino
07-01-2001, 10:48 AM
I have a 600 degree Lazer temp guage.I can mow my 7 acre lawn at 3750 RPm.s,in 80 degree weather,and hop off with it running,I checked the oil temp at the filter 170 degrees is the highest Ive seen it.I have seen 186 at the inlet of the big cooler,but the outlet is alway no more than 170.My steiners Onan performer 24 runs at 225 degrees in the same comditions.The amsoil filter IMO helps at least as much as the cooler,it holds another quart,but it keeps the oil spotless clean at all times.When I draain the oil,there is never any shiny glitters of metal dust in the oil,the filter takes them all out.This has to help a lot.I think this system could easily be retro-fitted to any kohler with an external factory cooler in the fan shroud,or you'd have to buy the adapter if you have a Kohler with no cooler i nthe shroud.The oil cooler is sold as a tranny cooler under the B&M name,its about 55 bucks,and its the 19000 GVWR 3/4" model,I have one on my truck,its the identical model,right down to the part#.the amsoil is about 125-150 bucks,and can be bought on line,if anyone is interested.The only downside to this system,besides cost,is that in the colder months in the beginning and end of the season,the oil doesnt get hot enough to burn off all the moisture,and the dipstick tube gets a milky buildup from moisture.