Winter preheat

[Jim Hartley]

Re: Winter preheat

I use a one burner campstove(5000BTU),it will burn for two hours + on low. I have about three feet of rigid ducting. The last two feet is three inch. I can get my hand only within five inches of the outlet with out it becoming unbearably hot. this a good test when deciding how close to the oil sump that I place the duct. I generally drain the oil into a 0ne gallon metal hydraulic fluid can which I can leave on a wood stove over night or a burner on low for thirty minutes or so. I make sure the oil does not boil. The Quick- read thermometer shows about 170 degrees. I also have a quality engine cover to contain the heat. The hot oil cuts quite a bit of time off the preheat.

Jim

[jdoran]

Re: Winter preheat

This won't work in real cold weather, but here's an idea:

I bought a rubber hose for ducting engine exhaust outside in a garage. It's the type you slip over the tailpipe.

I used to preheat my Sundowner engine with it at the airport tie down (no electricity nearby) The heat coming out of an exaust pipe is considerable, but safe-no direct flame. I shoved the discharge end of the hose in the bottom of my cowling and just let my pickup truck engine idle for 45 mins or so. It really warmed up the engine block well.

[Hank Jarrett]

Re: Winter preheat

There have been some great ideas for warming engines on here but there are two things to keep in mind. The first is obvious. Open flames and engine compartments with potential fuel vapors are a BAD idea! Make sure any combustion heater is well isolated so the fuel fumes from the engine can't get to the flame in the heater. Fuel vapors are heavier than air and when you warm up the fuel, the vapors will start spilling out of the cowl and rolling across the floor. Do you put that combustion heater under the cowl? You DON'T want to heat the engine THAT much.
The second isn't as obvious. Any hydrocarbon combustion exhaust is FULL of water vapor. In fact, there is approximately a POUND of water in the exhaust for every pound of fuel burned. If you warm the cold metal engine with wet warm air you will get a BUNCH of condensate on every cold surface. If it is below freezing at the altitude that you are flying that water could freeze and lock up under cowl parts with ice that aren't warmed quickly or all the way through. It also means every part of your cold engine is WET! I don't know about you but I don't like the idea of that warm water vapor condensing in my mags, control linkages or INSIDE OF THE ENGINE! Admittedly, when the engine warms up, the water will boil off, but I think I want a heat exchanger in the loop if I plan to heat with a combustion heater. No vapors at the flame and no water in the engine compartment.
I like warm and dry, not burned up or wet.
Hank

[alwaysoar]

Re: Winter preheat

How cold does it have to be to require pre-heat? I've heard 20 degrees F. ok not to preheat, though I don't usually fly when it's colder--my feet get cold.

[Karl Rigdon]

Re: Winter preheat

Years ago we built a pre heater for a friends BL65 using a Covair gas heater. We mounted it on a stand with a 12 volt electric fuel pump. With some ducting and a cover for the 65 Lyc. cylinders it would heat the engine in pretty cold weather. It required supervision so the heat exchanger did not overheat. The circulation fan moved a fair ammount of air. A heater from a twin that was no longer servicable for aircraft use might be modified and with much care could heat in remoted locations.
I have electric in my hanger so a 100k BTU shotgun heater works very fine.
I also bent a auto dipstick heater so the heated area was below the oil level. I would only power that about 1 hour before I planed to start.

[Peter Collin]

Re: Winter preheat

Dick.
Your plane looks great.
Good picture of the Moose too, he's a lucky moose he survived the bears and wolves.

Peter

[Forrest Barber]

Re: Winter preheat

Thank you Alaska guys , you make my day.... Nice Moose, glad to see you back on wheels. Forrest

[matsuthunder200]

Re: Winter preheat

cool pics Dick
I got off floats about 2 days before freeze up myself. I dont think i am going
on wheels i think ill go rite to skes the ice is almost ready seems early this year. its been below zero at night for the last 5 or 6 days. defenitly time to pre-heat and wing and tail feather covers. cant wait!!

[Dusty]

Re: Winter preheat

Propane heaters get pretty pokey below about -25 (as does my oven!). Burying them in snow, especially if they are setting on ice, helps significantly.

The SportCat heaters will NOT heat up a cold engine. They WILL keep a warm engine warm for 8 hours or so with a good engine cover. It'll run fine however you can cram it in there, and I've never burned anything down with one.....

The catalytic heaters make a LOT of water which freezes on everything. Check controls VERY thoroughly before starting, and just assume that everything will be stuck in exactly the wrong position so it won't surprise you if it is.

The trick to pre-heating it to get the oil - all of it - liquid. 2 hours on a cold engine is about minimum for any heat source. You can make em start well before that, but your oil pump then gets to suck up a big globs of frozen oil. If you can turn the prop over easily you've probably accomplished that. More is always better.

I let her warm up idling for about fifteen

Lycoming says go when it'll go, and that's what I've always done with Lycs and Continentals. Does Continental say something different?

Like most on here, I use the hunk-of-pipe-and-scat-hose method when I don't have electricity. I use an old soup can to hold the heater and regulate airflow (cut holes until the stove burns right), then a couple feet of 3" AL pipe, then enough scat hose to get in the bottom of the cowling. MSR stoves (I have XKG and DragonFly) are worth their weight in gold - or more. They'll burn just about anything you can get in the tank, are tough as hell, and put out more heat than anything similar. Mine typically run about 2 hours on a small bottle of fuel (on high), and that's how long I preheat. My hose lives behind the (extended) baggage in the T-cart and in the fishing pole tube in the Champ. Trapping wire is your friend....

[Jim Hartley]

Re: Winter preheat

The trick to pre-heating it to get the oil - all of it - liquid. 2 hours on a cold engine is about minimum for any heat source. You can make em start well before that, but your oil pump then gets to suck up a big globs of frozen oil. If you can turn the prop over easily you've probably accomplished that. More is always better

Good post Dusty! Heating the oil and then pouring back in is part of my preheat if possible. Potentially cutting the preheat time in half!

Jim