Detroit Diesel two-strokes and Chevy Corvairs

[RJ]

While pondering some cooling issues in another thread, it suddenly occurred to me that the two engines mentioned in the subject line above both have something in common:

Their secondary (and vitally important) cooling system is oil!  More so on these than others, due to the nature of their design.

No wonder there are specific oil requirements for both engines!

Will mull this over some more while I have breakfast. . .

FWIW. . .

[TomC]

EVERY Diesel engine, including the cruddy Oldsmobile 350 converted into Diesel from gas engine has oil coolers that are positioned to use the coolest radiator water first before the coolant goes to the engine.  On turbo engines, the main use of the oil is to cool the pistons with oil nozzles that are on the engine block shooting a continuous stream of oil to the bottom of the pistons.  Oil also cools the bearings along with lubricating them.  Just as important is the fuel system that flows at least twice what the engine uses to both cool and lubricate the fuel injectors.  So when you look at it, a Diesel engine has 3 cooling systems, and with a turbo, if it has an air to air intercooler, 4 cooling systems!

Just a side line-on some larger ship engines, the ocean water is sucked into the heat exchanger in the ship where it cools the coolant.  Then the cooled coolant goes to another heat exchanger that cools the engine coolant.  They put this extra layer of protection in case the heat exchanger leaks and won't introduce salt water into the engine.  Course the simplest is what is called keel cooling where the coolant from the boat engine goes to a series of pipes on the bottom of the boat where the motion of the boat against the water cools the pipes with the coolant inside.  In all actuality, a boat engine is the only really true water cooled engine.  All land based engines are still air cooled-albeit through a radiator.  Good Luck, TomC

[Chaz]

So do you think to keep a DD cool, one should also look into an auxilary oil cooler??
Sounds about right. I know there are the trany coolers, do you think they, or something like them used to cool the engine oil, would be beneficial?

  Just something to ponder over breakfast, (s**t missed that, lunch then)
        Chaz

[tekebird]

RJ is right as well as Tom,
However, unless you have repowered a DD should be able to keep itself cool with the factory engineered cooling system that is in good order.

most people neglect the cooling system in their cars too...

[Buffalo SpaceShip]

I knew there was a reason my 8V71 takes seven gallons compared to a big block gasser that might take seven quarts. Cooling, it is!

Chaz, while you could add an oil cooler, and use a tranny oil cooler (Hayden, etc.), you'd want to keep the oil from getting too cool. IIRC, DD specifies 180 deg. for coolant and between 200 and 215 deg. for oil on the 8V71. Back when my oil temp. gauge used to work (and I'm trying to fix it today), it stayed within that range. If the oil runs hotter than than, and the stock system is in order, it could benefit from some add'l. cooling. But I'd definitely use an alarmastat valve or something inline to prevent the oil from running too cool on cold days.

Since our coaches aren't stock setups due to the V730s, we sometimes have to re-engineer the cooling and/or trans. cooling setups. And maybe the oil cooling, also. In addition to the engine temp. gauge,  mine has a setup that (when running properly) can monitor temps. for engine oil, tranny oil before the cooler, and then tranny oil after the cooler. It helps alert me to potential issues, for sure.

Cheers,
Brian B.

[TomC]

One thing for sure is the engine oil cooler from Detroit was designed well for cooling the engine oil-so leave it be.  I've put the auxiliary Hayden transcooler on mine, and need to do some fine tuning, but it works well.  Hopefully it will make the difference in Aug when we go to Mammoth.  Good Luck, TomC