912 engine preheater

[herman pahls]

My 1999 vintage Rotax 912 100hp (without soft start) is difficult to get started whenever the temps drop below 60 degrees F which is most of the time where I live.
I have installed the latest generation 912 flywheel which supposedly retards the ignition even more at start up and a new battery and starter.
My next step is to convert to the latest generation Rotax ignition modules with the built in soft start feature.
My definition of hard to start is when after going thru the starting routine, it does not immediately start and idle like the car I drive to the airport.
I feel sorry for the starter when it repeatedly acts like it is pushing against a wall and wonder when the engine will need to be removed to replace the Sprague clutch from the abuse.

Everyone but me has already figured this out, but I recently found that preheating is amazing.

I have known about the Reiff 912 phone activated preheat systems for years but hesitated because the system requires several hours to get up to temperature and I never know when I plan to fly.
I thought that it was hard on the engine to leave the heat on full time but I learned that the condensation that forms from cycling the heat on and off is what damages the internals.
Then I rationalized that if I lived in southern California where for several months of the year the night time temps do not drop below 80, how can it hurt the engine to leave the pre heat on full time?
Hal Stockman from Rotax 912 Big Bore Kits, suggested I go to Napa auto parts and pick up some 2" x 5" self adhesive 50 watt engine block heater strips.
I found these strips on Amazon for $18 each and installed 2 on the bottom of the 912 engine case and one on the oil tank and found a thick moving blanket to drape over the cowl to help retain the heat.
I came back the next day and was shocked how warm the cowl felt.
The oil temp gauge indicated 112 degrees and it started on a near freezing day like my car does.
I disconnected one of the case heaters and the next day the oil temp guage indicated 96 degrees before start up with the same immediate easy on the starter and Sprague start up.
This still leaves a starting issue when away from home in the cold mornings of the Idaho Backcountry but that is only a few days a year.

I would be interested if there are any comments regarding leaving the preheat on full time other than constant power usage?

Has anyone converted to the Rotax modules with the built in soft start and noticed an improvement when starting the high compression 912's with or without a big bore kit?

Thanks
Herman

[HighWing]

Herman,
Not an answer to your direct question, but possibly helpful, a local guy with an early 912ULS with nearly 1500 hours on it developed a starting routine that works for him. I use it on my 80 hp and it results on easy quick starts with no bouncing around.

He will start with throttle full closed, Ignition off, Crank for about ten seconds with full choke. Rotate throttle to an approximate fast idle. Ignitions on and crank again with full choke. Presto. I don't think he has yet to install the aftermarket - for him - Sprague Clutch.

[Av8r3400]

Herman, do you have an auxiliary fuel pump? I put one in the Mangy. When it's cold, I will run the pump for a few seconds with the choke pulled, to bring fuel up into the carbs, through the enrichers and then shut it off. Only then do I go into the start procedure.

I think this may be doing the same thing as what Lowell is suggesting by cranking with ignition off first.

[jiott]

It seems to me that 10 seconds of cold cranking is awful hard on the battery. Wouldn't it be better to do this cranking with the ignition ON; you may get a start long before the 10 seconds are used. Just wondering.

[HighWing]

I guess it would depend on the battery. I have used the technique for many years. I don't fly as much as I used to and the ten seconds pales compared to what the engine needs to recover from its 3 month deep sleep to full awake. Than add in the shakes and rattles before it begins to roll suggests a much stressful start considering the moving components. Then again, back in the day, the early ULSs shook mercilessly when starting frequently throwing the carburetors out of the sockets. This is why the "soft start" and "slipper clutch" bandaids were eventually developed. The stress of the rattling prop blades against the gearbox backed up against the crank and pistons was in my view something I didn't ever want to deal with, yet I did witnesses it first hand during our week long group flights together. With my 80 hp Rotax, ten seconds of smooth cranking followed by an instant start to idle after another couple of seconds with little if any stress on the engine seems like much less stress on the $$$ part with possibly a bit more stress on the cheaper much easier to replace part. My friend has been flying his IV with ULS for over 15 years.

[jiott]

Herman, leaving the heater on continually would concern me about an electrical malfunction and fire. In your mild climate just plug in the strip heaters when you get to the hangar and I'll bet that in 1/2 hour (about the time it takes to do your pre-flight and prepare to fly) it will be warm enough to start easily. I use a cheap "milk-house" heater whenever it is 40F or below and one hour of heating is plenty for me (my engine 912uls has the soft-start).

[herman pahls]

Thanks for the responses.

The start procedure I use includes turning on the electric pump to make sure it is making pressure and to fill the float bowls if needed.
I then pull the enrichener with the throttle fully closed and turn over the engine with the ignition off for 5 seconds.
Then I wait 15 seconds, advance the throttle to a fast idle, engage the starter and then flip both mag switches to give the starter a head start on the mags.
In warmer weather this works almost flawlessly.
Go camping at altitude in the Idaho Backcountry where it often gets near freezing at night in June and you sometimes wonder if the starter or sprague will destroy themselves before it starts.
Once started that day it fires off perfectly.

Larry, the enrichener seems to getting plenty fuel into the venturi without enrichening with the electric fuel pump on.
I have learned that too much enrichener and it will act flooded when it finally starts.
I wish I had your updatedignition system even though your engine starts fine with out the soft start feature.

Lowell, ever since you gave me the starting routine, it starts great in warm weather but not cold.

Jim, I also am concerned about the power constantly on for fear of fire.
in the past it was common procedure to leave a 100 watt bulb going inside the aircraft to keep the avionics warm.
I am sure the 100 watt bulb is safer than heat strips.
Maybe using a low amperage circuit breaker than the traditional 20 amp would add some safety in case of a short develops.
I will experiment, but doubt a 1/2 hour will do much.
Reiff, the company that makes the pre heaters suggests 3 hours to get 20 degrees temp increase with their 150 watt system and I am only using 100 watts at the time.
They say these lithium batteries actually crank better if you place a load on them for a few seconds and then wait several seconds.
Seldom does it freeze here but it sure has the last few weeks.

I may fly several times a week but for only 30-45 minutes.
So having an engine that starts simply and does not feel like it is destroying itself makes it a more enjoyable process.
Maybe I have a problematic starting older 100 hp but it sure runs well once started.
I am hoping pilots with similar high compression engines would have the answers.
My goal is to install the Big bore Hi compression kit which will only make the starting more difficult.

Herman

[Norm]

This has morphed into a starting sequence procedure so I have a newbie question.

Does anyone use a primer on the 912. I am fairly new to 912 operation and I know when I put a primer on my 582 the starting was much easier. Would this work on the bings on the 912 as well as it does on the 582?

[SkySteve]

Norm,
I have an 80hp 912. I did install a primer and use it for all "first starts" of the day regardless of temps. I prime 5 or 6 pumps, do not use the enricher, pull the throttle out about 1/4", switch mags on and turn the key. It starts every time. Our temps range between 100 F and -20F but I don't fly below about 25F. I do not have an engine heater. My plane is always hangared.

[Norm]

Thanks Steve Think I will do the same.

[jiott]

Herman, you might give my "milkhouse" heater system a try. It is 1500 watts, quite a bit more than the 150 watt block strip heaters. A half hour at 1500 watts may do more than you think. I realize that all 1500 watts of hot air is not going into the block, but still it is quite a bit of heat circulating thru the engine compartment.

[herman pahls]

I have done more experimenting with engine preheating using Kats engine block heating strips from Amazon and have settled on the best combination for my application.
Jim.

I am too impatient to wait for a heater even if it only took only a 1/2 hour before flight.

These self adhesive strips are 2" x 5", produce 50 watts each and cost $18 each.
I started with 2 strips on the bottom of the 912ULS and 1 on the oil tank.
This gave 112 degrees oil temp before start up and the 912 starts and idled like I had just turned it off.
I cover the cowl with a quilt and it feels almost too warm.

I disconnected one of the engine heaters and the cowl felt noticeably less warm and the oil temp read 96 degrees before start up and it started perfect.

Then I disconnected the oil tank heater and the next day the cowl felt barely warm with only one block heater, the oil temp was 76 degrees and it was hard to start. Just like it is when I do not preheat.
Hard to start to me means the starter acts like it is up against a wall and it takes several attempts to start.

I went back to 2 heaters and am making a dedicated extension cord to power these strips that add up to 100 watts.
The extension cord will have a 3 amp fuse on the hot leg of the cord.
If I am doing the math correctly, 100 watts only requires about 1 amp of current so I am going to a low amp fuse to reduce the chance of fire if there were to be a short.

I especially like the fact that the engine gets up to take off temperature in 2 minutes instead of 10 or more and we had a rare snow here today.
I can use a cell phone activated switch if I pre plan a flight by 6 hours instead of leaving the heaters on full time.
Herman

[Av8r3400]

I went ski flying Sunday. It was about 25º F here when I started preheating with my "cube on a stick" system. After about 30 minutes I got bored waiting and fired up the plane.

I was showing about 70º F on the Dynon for oil temp at startup and no issues starting. I do have the low compression Zipper kit on my engine, so that does make starting easier.

[Paul Z]

If you want to make it easier to start, I would recommend a oil tank heater and a strip heater on the bottom of the engine. If you diet the oil warm, it will flow thru the oil ports easier. I put a set of strip heaters on and it really helps. I also added an oil thermostat which reduces the time to warm up.

[kitfox2009]

Hi guys
Not sure if this is the proper thread but I just tried an experiment this morning when cold starting a mid 90's 912 UL.
The ac is stored in an unheated hanger so I always throw a sleeping bag over the cowal and blow heat in through the front airducts untill the engine cylinders feel a bit warm. Usually takes 45 mins or so depending on outside temperature. Today it about 5 C so I didn't apply much heat.
The engine cranked over just fine but never fired once,
I then used a heat gun and applied heat directly to the modules until they were quite warm.
Engine fired immediately! !
Not sure why but as someone mentioned before maybe some of these older modules need a bit of a warm up before they make juice.
Would anyone else like that experiment with this!!!!
-Cheers
Don

[Paul Z]

When I get another plane I'm going to get a real heater.
https://aerothermheaters.com/

[jeffbock]

Any experience with the REIFF engine heater? Has pad for bottom of crankcase and band for oil tank. has a thermostat which is good.
Comments appreciated before I call Spruce. Jeff

[kmach]

I use the Reiff 150 watt. Works good. Needs to be plugged in for a few hours . Use an insulated cowl cover to keep the heat in.

[mr bill]

I have the same unit, same comments. Works well.

[Wheels]

I looked at the company Paul Z recommended.
I bought one. It will be here in a few days and I"ll report on my happiness or lack of it.
Seems that the idea of heat soaking the whole compartment and recirculating the air every 3 or 4 seconds will answer the problem of condensation in my unheated hangar. The safety features and thermostatic control give me confidence that I won't be sweeping up any Kitfox shaped ash heaps.

[Paul Z]

For the amount of money we put into our planes, I can not understand why some people get cheap on a heating system. The idea of sweeping up ashes crossed my mind more than once.

[Slyfox]

Now that Paul brought up the fire possibility. Here is something I've been doing lately. I turn off the fuel. Lately my fox has been leaking fuel out the right carb. ya, I know fix it. Well I haven't quit yet figured out why. let it sit a couple days and I see a spot of fuel on the floor. Pulled the cover off and it's coming out the air filter. could it be the floats, they seem ok. could it be the needle and seat. could it be just the fact that now I have 28 tires in the front and the nose is higher, could be. I can change the floats, want the blue ones. also waiting to see how they work out. Or in my case, I just turn the fuel off. Now I have a new problem, what if... what if I leave it off and take a flight and it doesn't do anything until I hit the throttle, may not work that way, but I worry about that. so what I do, redneck I know. but I take a piece of duck tape and put it on my altitude indicator. The first thing I do when I get in the plane is adjust for altitude. yup works great. so I grab the tape and turn on the fuel than get in the plane. works for me. now there is no chance of fuel and vapor in the hangar when pre heating. that piece of tape gets stuck on the right stick or somewhere like that out of the way after I take it off. just what I do. now a lot of people have a carb drip pan under their carb, what if, there is still fuel there after sitting. just some thoughts.

[rv9ralph]

Several years ago, first preflight after my condition inspection, when I tried to sump the gascolator.. no fuel flow. I forgot to turn the fuel back on. Test it, maybe that will be your warning the fuel is off.

Ralph

[jiott]

I turn my fuel off after the last flight of the day, and I have forgotten to turn it back on a few times. Its no problem because the engine will start OK but start to cough very soon, long before the warmup is complete. No real danger of having it quit on takeoff.

[kmach]

I turn my fuel off after each flight as well and have the same experience of not worrying about forgetting to turn it on , because it won't run long enough with it turned off to get into trouble.

[efwd]

Do you think fuel injected systems might last longer before stuttering?

[PapuaPilot]

Do you think fuel injected systems might last longer before stuttering?

I have a FI Continental engine and am unable to prime my engine if the selector is off. The boost pump is between the header tank and selector.

[airlina]

Simple fix here guys is to put a liitle red flag with an alligator clip on your master switch anytime you shut off a fuel valve. You will never forget to turn it back on. Bruce N199CL

[Wheels]

who hijacked this thread?

[rv9ralph]

Thread Migration? It's as insidious project migration.

Ralph