How hot should the cooling water temp be?

[SloopJonB]

Originally Posted by MarkSF

"Remember guys, that the thermostat will control the maximum coolant temperature"

Most of the time that's true, but only if the cooling system has sufficient removal of heat. For example, a car standing in traffic has no air passing through the radiator, so the thermostat is likely to be wide open and the switch for the electric fans is controlling coolant temperature.

Pick, picky, picky. I can one up you though - I've never seen a BOAT with electric cooling fans.

[Rockter]

MarkSF :

Most of the time that's true, but only if the cooling system has sufficient removal of heat. For example, a car standing in traffic has no air passing through the radiator, so the thermostat is likely to be wide open and the switch for the electric fans is controlling coolant temperature.

Well done, Mark.

Yea, and in your boat, if you shut the water intake off I promise you it will (ultimately) behave independently from the thermostat.

A plastic bag over the intake will do it too.
.

[hellosailor]

Boats aren't cars. The engineering and physics applies equally to both, but different choices have to be made.

With raw salt water cooling, the main criteria is to stay below 145F because around that point salts crystalize out of the water, your cooling passages get blocked up, and your engine overheats and dies. Doesn't matter if 200F is more efficient, because the engine will still die very young.

On the other hand, running an engine "hot" will produce more power, all things being equal. First the engine has to be designed for it, running hotter than the manufacturer's recommendation tends to do things like burn exhaust valves and again, the engine dies young.

In the 70's Porsche had these radical engines running 210F because a hot cylinder wall allows the combustion to continue longer and generates more power. A cold(er) cylinder wall literally quenches the flame front in the cylinder and stops combustion. So, Chevy copied the concept in the Chevy Vega. Ooops, Porsche owners respect their engines and check the oil and coolant. First-time Chevy buyers don't know about that, and the Vega engines got a reputation for disaster. Not the engines fault--it is just that overheating becomes a bigger issue when you start with hotter engines, and oil acutally cools the cylinder walls, not just the coolant.

So unless your engine maker specs a hotter thermostat, you stick to 170-180F for an engine with a heat exchanger and closed cooling, or an engine in fresh water, and something like 140F for a raw water cooled engine in salt water. If the newfangled engines are running hotter thermostats, that's great, as long as it is the design spec. The actual temperature at different parts of the systme, different parts of the engine block, may vary significantly from the thermostat temperature, even when it is all heat-soaked and stable. In theory, a properly designed engine installation takes that all into account.

That's also one reason to run an engine compartment blower, even with a diesel, and especially on shut-down. When the engine shuts down, there's no cooling and the block temperature can actually rise, cooking the oil. Running a blower helps cool it down sooner, should extend oil life and prevent some of the tar buildup internally.

[Capt Len]

I had a 471 Detroit idling on station for along time. It overheated because the slow turning impeller couldn't push the hot water down and thru the keel cooler. Always lots of angles to consider.eh? I've also done the plastic bag in the inlet gig but I can flush or pressurize the sea **** with domestic fresh so no biggie..

[SloopJonB]

Originally Posted by hellosailor

In the 70's Porsche had these radical engines running 210F because a hot cylinder wall allows the combustion to continue longer and generates more power. A cold(er) cylinder wall literally quenches the flame front in the cylinder and stops combustion. So, Chevy copied the concept in the Chevy Vega. Ooops, Porsche owners respect their engines and check the oil and coolant. First-time Chevy buyers don't know about that, and the Vega engines got a reputation for disaster. Not the engines fault--it is just that overheating becomes a bigger issue when you start with hotter engines, and oil actually cools the cylinder walls, not just the coolant.

My father bought a new 72 Vega GT fastback. It was a sweet little car - at first. He always maintained his cars by the book and the Vega never overheated.

Other than premature rust perforation, the problem with that car was that GM tried a new technology of silicone treating the aluminium cylinder walls and iron plating the pistons. This was done to eliminate iron cylinder liners in the alloy block - cheaper, faster, lighter and easier.

The problem was - it didn't work. The silicone in the cylinder walls wasn't enough to prevent premature wear with consequent "worn out engine" problems like excessive blow by, oil consumption, blue smoke etc.

The same or similar processes have been tried by Benz and Jaguar with similar lack of success for similar reasons.

GM raised the engine temps back in the day and continues to mandate high engine temps for emissions reasons as well as a tad more power. My 02 Corvette runs 217 before the fans come on. It is unlikely they would use Porsche air-cooled engine technology in a water cooled economy car, particularly when they were already hooked up with Cosworth on the Vega project.

[hellosailor]

I was told the siliconed-aluminum cylinder wall was their implementation of Porsche's technology. Maybe they just didn't get that right. It wasn't air-cooling that they tried copying, but the metalurgy and the high-temperature engine.

The real problem with that car, like so many others of the time, was that GM, like the rest of Detroit, just wasn't paying attention to much of anything except the models they hired for the auto shows. New cars were built for the new car buyer of the time, someone who would usually own it for a maximum of 2-3 years and then get rid of it. I wonder, how long does the new sailboat buyer keep the average newly-bought sailboat in comparison??

[lillia28]

The issue with the Vega engine was head gaskets. Supposedly a copper head gasket was ordered by engineering, but a steel and asbestos gasket was used to save money. The head gaskets would leak, and once the engine overheated the block would warp and cause unbelievable oil consumption. In any case it was not the silicon infused aluminum block alone. If I remember the Vega used an iron head, and the difference in expansion rates between iron and aluminum caused the head gasket problems. I had several Alfas back then, (all aluminum block/head with steel cylinder liners) which were noted for head gasket problems. The hot fix was an all copper head gasket, so I have some faith in the story. The McLaren Can Am cars used an aluminum silicon block v8 and were remarkably successful. GM insisted the Vega's problems were assembly issues caused by labor trouble at the Lordsville, Ohio plant, but I wonder how the union guys got that head gasket switched.
Sorry for bring off track.
Lou

[hellosailor]

Lou, I suppose we can be grateful that the UAW doesn't take actions in boat manufacturing plants. When I opened up the door panel in my old Mustang, I found a ball joint separater tool inside. Don't ask me why it got put there, but the car clanked less without it. And in that same era, one of the assembly lines was being sabotaged by putting glass Coke bottles inside the driveshaft. Eventually they'd shatter and the glass would cut the shaft, from the inside.

In contrast (coming back on topic) we were expanding the electrical panel on a Pearson 32 and figured out, the electrics entered the boat on one side, the water fill and exhaust on the other, and everything crossed under the companionway entrance instead of just being routed on the side it came in on. I could only think that the boat had been built on a Friday, the guys got to partying real hard, and when they came back to the shop Monday morning they said "Gee, lookit that, we did finish that one."

What can I tell you, I'm still impressed by things like the dust bin recessed into the cabin sole on the old Sabres, and the curved companionway steps on the old Benes. Or cockpit sides angled so they fit right when you're heeled under sail, instead of parked at the dock.

[SloopJonB]

Originally Posted by hellosailor

Lou, I suppose we can be grateful that the UAW doesn't take actions in boat manufacturing plants. When I opened up the door panel in my old Mustang, I found a ball joint separater tool inside. Don't ask me why it got put there, but the car clanked less without it. And in that same era, one of the assembly lines was being sabotaged by putting glass Coke bottles inside the driveshaft. Eventually they'd shatter and the glass would cut the shaft, from the inside.

Not just the UAW - I once had a 66 Porsche that rusted through the rocker panel under the drivers door. The bodyshop found a soggy rag in there when they were prepping for new metalwork.

[lillia28]

Not that I disagree entirely, but there is a difference between bad design and bad assembly. As the "proud" owner of several Italian gems, it seems the Italian work week consists only of Monday's and Fridays. I'm not sure if they alternate or not. I ordered some parts once and they said I'd get them in September because the factory closed in August. I thought they were kidding! I am not sure why you object to innovative thinking for storing the emergency tool kit, unless it was the missing genuine vinyl pony embossed pickle fork cover? Surely that would have stopped the rattle!

As a rule, I only buy cars that are 5 -7 years old. I figure if they last that long, they must be Wednesday's children. Just to keep this on track, all my Alfas ran cool, and were equipped with the most intricate thermostats I've ever seen. They cost $15.00 each when Murican thermostats cost $1.79 and the lira was about 400 to 1! Which must prove something!
Lou