Preheat engine with hot air?

[Furi]

Possibly an off the mark question but hopefully not.... :)

I know there are engine coolant heaters that could be installed to be able to preheat the engine coolant.

But is it possible to preheat the engine using hot air blown into the intake? Lets say 90 degrees F.
Comparing to heating the coolant is using air:
1. Just as effective?
2. Half way?
3. Not effective at all and just a lot of hot air?

[Growlerbearnz]

You're talking about preheating like during winter, which keeps the engine warm so it's easier to start and causes less wear, right?

I can't imagine preheating an engine by blowing hot air into the intake. You'd preheat the air filter a bit, but the hot air wouldn't make it all the way through all those pipes into the engine- for the hot air to be drawn into the engine the engine would have to be running, which kind of negates the purpose of pre-heating. Blowing hot air into the engine while it's running would help it warm up a touch quicker, I guess, but I imagine a few extra degrees of intake air would be insignificant compared to the hundreds of degrees from the fuel burning inside the engine.

You could aim your hot air at the engine block, but that seems an inefficient way of transferring heat. Much better to heat the water directly with an immersed heating element, or heat the oil with a sump heater. Heating liquids works fairly well because the convection currents tend to move the liquid around, distributing the heat a little more evenly.

Incidentally, a few diesel engines don't use glow plugs for starting from cold, they heat the incoming air instead using an electrical heater screen. Weird.

[Furi]

Yea; I didn't know how far the hot air can get by opening valves, etc. when the engine is off in order to be effective. So basically a lot of hot air then... :) I did read in a few places that the hot air into the intake might improve gas mileage but it was dependent on conditions.

That's Interesting about the hot air ignition. I wonder in what cases it makes sense to heat the air coming in as oppose to having glow plug. Engine design considerations?!

Thanks for the insight and alternative methods of heating the engine. In case of a heating element would you just immerse the heater element into the radiator?

[Growlerbearnz]

Intake air heaters are more reliable than glow plugs (only one thing to break rather than four, lives in the air intake not in the combustion chamber), but they can take a little longer to warm up, and aren't usually as good at starting the engine or helping it run smoothly when it's cold. Intake heaters tend to be found on more industrial engines, and Landcruisers because Toyota.

The few water heaters I've seen were inserted in the lower radiator hose or a heater hose, and when they heat the water it just circulates by thermosyphon (hot water rises, pushing cold water through the engine).

Here's a picture of one from Ebay:

s-l1600.jpg (48.18 KiB) Viewed 5565 times

[TieMyShoe]

like a cummins grid heater?

[204explorer]

There seems to be a lot of confusion here. Lol. I have a in-line coolant heater but it is not installed anymore. In my vehicle, a suzuki xl7, it just heated the radiator. It depends a lot how your thermostat is hooked up. I went with a glue on oil pan heater. That's better in my opinion anyways. An other problem is that some engines base the pre- heat duration on coolant temperature. So if your coolant is nice and warm the pre-heat does not come on and the engine will not start. That's why it's better to use an ambient temperature sensor.
The easiest thing to do is to install a block heater. Works fine for most applications as long as you can plugged it in somewhere.

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[Growlerbearnz]

like a cummins grid heater?

Exactly like that.

There seems to be a lot of confusion here. Lol.

Much of it on my part, I expect. Here ice is something you put in your drink- if water goes solid outside it's clearly the end of days.

The easiest thing to do is to install a block heater.

That's the one I was forgetting! Replaces a freeze plug and heats the water in the jacket. Bizarre.

[204explorer]

We live in a deep freezer here for five to six months. Once I get my van ( two more weeks. Can't wait) I am planning to put an espar heater on it. Not sure if that has been done lots. I will post the results on here.

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[Growlerbearnz]

Nope nope nope nope. 3 days in Fairbanks in December was enough cold for me for the rest of my life.

[Furi]

We live in a deep freezer here for five to six months. Once I get my van ( two more weeks. Can't wait) I am planning to put an espar heater on it. Not sure if that has been done lots. I will post the results on here.

Congrats on your new van. That is the best option, specially if you are living in cold climates. Also the option to have hot water and heat the cabin if making a camper. I would've gone that way but my need to heat the coolant would be sporadic and there is the cost consideration as well as the amount of work involved. One of the members; Felix has done a pretty nice setup if you like a reference... But look forward to seeing your setup once you have it.

http://dinoevo.de/diesel-coolant-heater-hot-water-tank/

The few water heaters I've seen were inserted in the lower radiator hose or a heater hose, and when they heat the water it just circulates by thermosyphon (hot water rises, pushing cold water through the engine).

Found those on ebay. Thanks; good option. What are the coolant temperature ranges? say at idle, average temperature while driving and when considered overheating? Some diesel forums I've looked up have an avg temp of 180 but wasn't sure if its same for these engines.