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http://www.samsmarine.com/forums/archive/index.php?t-1619.html (http://www.samsmarine.com/forums/archive/index.php?t-1619.html)

It's interesting to compare what's normal for them and what's normal for us.   The comments about loading, speeds and temperatures are  especially pertinent.   This makes me thankful my engine is "only" 277 HP.

On a sort-of related note, I just changed out my Bendix air compressor's two coolant hoses.   The old ones were so dried out and crusty-looking that one actually broke as I was undoing it!   I guess they were from 1990 when the bus was new.   Talk about dodging a bullet.   The problem was, the engine was still full of coolant, so I had to catch as much of it as possible in a bucket underneath, plug the engine's coolant ports with 20-cent rubber bungs from Ace Hardware, then I could take the despicable old hoses to my local friendly hose-monger.   He made up a new pair, and also sheathed them with high-temperature wrap to help prevent them drying out like the old ones did (they're quite close to an exhaust manifold).   Putting them back on yesterday was No Fun.   The top hose was easy, but the lower one was probably the worst thing I've ever had to do to the bus  -  my whole chest and shoulder is scratched from contorting myself to reach its lower connection just above the oil cooler, and all the time that I was futzing with it trying to get the thread started without cross-threading there was coolant pissing out over me and everything else.   Anyway, it's now back on, it doesn't leak, I refilled the engine enough to cover the Low Coolant sensor, and on Wednesday I'll take the bus to ABC Bus just down the road from here to have them change out all the coolant and check the other vital signs.   When ABC drains all the coolant, I'll recheck that damned lower connection that gave me so much grief and blood loss.   And if you're wondering why I did all this if I'm getting my coolant changed next week anyway, I hadn't ever intended to actually change those hoses right now  -  I just wanted to check their threaded ends so I could buy the correct replacements from Mesa Hose before going to ABC, then I would replace them there myself to save some labor and parts mark-up costs.   I tried to bleed any air from the petcock on the top of the coolant crossover tube when I briefly ran the engine last night, but nothing at all came out.   I guess I can't bleed the system until the thermostats open and start allowing coolant through that pipe into the radiator  -  last night I ran the engine for only a few minutes, just to make sure there were no leaks.   Let's hope the 1.5-mile trip to ABC won't cause any problems if there's still some slight air in the cooling system.   Do 6V92s self-purge entrapped air?   (Their header tank is at atmospheric pressure, so I assume it's not a pressurised system per se.)   I can't find any other petcocks on the top of the cooling system  -  are there some others hidden somewhere else on the engine itself?

John

good link to read . thanks

The whole link is interesting. Too bad they talk more about air through the engine instead of the fuel injected, which can be a little misleading conceptually.

Fuel makes the heat, asking for power at lower RPM's means more fuel injected per revolution, means higher temps.

But, as long as folks understand that under load, higher rpm's is the strategy for cooler temps, the desired outcome is achieved.

Gear down often!

happy coaching!
buswarrior