diesel cooling components

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jmeirhofer

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This may be a stupid question but when I can't sleep I think about this kind of stuff.

On my cats the freshwater flows though the after cooler, turbo(i think), trans oil cooler and of course heat exchanger.

Why doesn't the antifreeze flow through all but the heat exchanger, which of course would have both? Wouldn't that significantly cut down on the saltwater deterioration? Are newer motors this way?
 
Double check your system I'm pretty sure that's how it is. That's why you hold 7.5 gallons of antifreeze plus another half in the reservoir. I believe the only thing the raw water flows through is the heat exchanger then into the exhaust.
 
your engine handbook they usually have diagrams of all systems.
 
raw water flows thru other coolers (tranny, inter cooler, fuel and oil cooler) better cooling... Your coolant typically will be around 180 degree and would not cool anything, if anything it would heat your gear oil, fuel, air charge.. Makes no sense :)

Raw water doesn't flow thru the turbo, oil does
 
Dave. It does flow through everything I mentioned except the turbo. Hence why you have to change the zincs.

Bruce - I have manuals and do know where it flows. It is not an operational or manual type of question. More an engineering curiosity question

Pascal. Not sure why I said turbo. I know better. I blame it on early morning hours. Lol. What you say does make sense though. Especially for the trans fluid. But I did think it would still be better for the after cooler. How warm is that water after flowing through the other components?
 
The aftercooler purpose is to lower the temperature of the air going into the engine so that it is denser and can burn more fuel. I ve never measured the exact temperature of the raw water as it exit the heat exchanger before reading the aftercooler but it is significantly lower than the 180 deg coolant and also than the ambient air intake temperature which has to Be close to the engine room temp, probably 100 deg under way.

A good question would be why don't diesel boats use air intakes on the inside of the ER to get cooler air in instead of the hot Ir from the ER...
 
IIRC some engines have coolant cooled after coolers. Engines are different and I am surprised yours does not show a full cooling system diagram. Diesel makers books are usually written for anyone anywhere to be able to understand how things work.
 
quote:
Originally posted by PascalG

A good question would be why don't diesel boats use air intakes on the inside of the ER to get cooler air in instead of the hot Ir from the ER...

Click to expand...


If the boat side air intakes vents are properly sized and/or you have good high volume fans pulling in outside air your engines should be seeing ambient temperature air at their intakes.

With the proper air intake system I've run boats where at the end of the day the engine room air temp. with the air exchange fans on is no hotter than the outside ambient air temps.

The 76' and 80' Lazzaras come to mind.
 
I would think putting the intakes directly outside would cause at least a small bit of problem with to much humidity. Plus as Bill said, unless the engine room is getting cold air from outside the air would get heated in the plenum anyway.

Bruce - Sorry if I have not been clear. Let me try again. I do have the manuals for my motors. I have studied them. They do have diagrams of where water and or antifreeze flows. I know how the system works and what does not as well as understand the maintenance behind it which I perform to the T. This question is unrelated to any of that. It is just a question of "why do they build it that way" that I was thinking of very early this morning when I could not sleep. Pascal has made a very valid point that I had not considered when I posted the question. And followed it up with a later point on the after-cooler.

Now that I have opened this box of worms. I intend to make me a log book and do some temperature checks through the summer. I may even try to figure out a way to hook a temp sensor to each end of the after/inter cooler and check those temps right after start up and before shut down. Or just use my trusted heat gun. I may even buy an indoor outdoor thermometer unit and put the control at the helm so I can see the difference between ambient and engine room temps.

Sounds like a fun research project. I wonder if I can get a grant from the federal government to do this study for the next ten years? LOL
 
There are several ways to monitor those temps. An IR gun and a log book is one of the cheapest. And the gun can be used to keep an eye on other temps. as well. You can also use temp. monitoring strips or paint that changes color according to the temps. they encounter. Or get fancy and use permanently mounted thermocouples going to gauges.

A remote ER temp. gauge is handy too. http://tinyurl.com/dyjhewv
 
I guess at high speed the engines suck so much air that it doesn't have time to heat up much on the way from the air intakes.

On many boats the blowers are set up to extract air so that won't do much except pulling more air in the ER thru the intake. Not much of an issue I guess

I agree that recording engine parameters in the log is good oractice and establishes a baseline which may be useful
 
The way my motors are laid out I can see where starboard motor would receive cooler fresher air. The filter/intake is just a couple feet from the hull side openings. The port motor filter/intake is centerline. Since hot air intake significantly effects turbos it would stand to reason that more HP is going to be lost on the port motor unless you can get the intake air at about the same temp.

This has totally sidetracked the original question but much more interesting.
 
Bill - I was thinking of this to monitor ambient temp at each intake.

http://www.amazon.com/Meade-TS33C-M-Temperature-Humidity-Sensor/dp/B004K6LOR8/ref=reg_hu-rd_add_2_dp

And using my IR gun to check the in and out of the after coolers but those would work pretty easy too. Not real scientific but good enough for his experiment. If the cable is long enough I could wire them back to the helm and just tape the sensors to the intake and outflow of each after cooler. I could record the temps on a spreadsheet on my iPad at the helm a few times each run.
 
The seawater in your CATs flows first through the aftercoolers and then into the engine heat exchangers. You want the intake air as cool as possible to maximize the air density in the cylinder. The air gets very hot after the turbos which run around 220. Then the water goes to the engine exchanger and the gear cooler. The oil cooler, IIRC is fresh water cooled. As Pascal said your marine gear runs cooler than the engine fresh water temps so your fresh water system would warm the gear oil.

When I had my engines surveyed the CAT mechanic carefully measured the temp gradients through the seawater system and fresh water system. The seawater inlet versus outlet gradient was 40 degrees and the fresh water jacket inlet versus outlet gradient was 32 degrees.

My engine room has large air intake tubes that funnel cool air from the engine room vents directly to the air filter boxes, but I don't know how much this really matters when you consider the cfm at cruise speed. Although the airflow when underway through the vents is pretty good, once you come to stop it really heats up with 6000 lbs of hot steel and no airflow. I think the amount of airflow into the intakes is staggering. About 1600 cfm at WOT for each of my 10.4 liter aftercooled 3208 diesels. Also, someone mentioned the coolant volume, my 3208s hold 15 gallons of coolant per engine.
 
My 3126 raw water flow goes to the exchanger first. The after cooler is last with everything else in between. No room for tubes to funnel air from the vents.
 
My Cummins the air tube from the turbo wraps around the end of the engine to get to the intake. Including the after cooler in the cooling system would add significantly to the hear load and probably require a larger heat exchanger. I agree it would reduce salt water problems and I do think some smaller engines are set up that way.

The why is probably because intake and exhaust are always on opposite sides of an engine. The turbo is mounted on the exhaust manifold but needs to push air to the other side of the engine to get to the intake, the after cooler is stuck in the middle of that pipe.

Consider that these engines are first designed for trucks etc then stuff is bolted on to make marine versions.
 
The CAT 3116 aftercoolers are cooled using coolant. With the 3126, they went to raw water cooling.
 
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