Starting Cold Engines

Tech Shorts September 25, 2004 0
One of the finer skills snowmobilers acquire is how they go about starting engines in very cold temperatures. Normally, the engine is so stiff...

One of the finer skills snowmobilers acquire is how they go about starting engines in very cold temperatures. Normally, the engine is so stiff that even electric starters are not able to do the job if you just go out and crank the key.

One tactic is to remove the drive belt, removing the drag on the primary caused by a rock hard belt. Warming up the drive belt and re-installing it after the engine fires is a good one, just be careful to not rev the engine above idle without the belt installed!

Don’t just walk up to the sled and turn the key or pull on the rope as hard as you can. All of the parts are stiff and there will be great resistance. All of that injection oil is sitting in the bearings and cylinders and acts like glue. Give the rope a few gentle pulls with the ignition off, very slowly and all the way through, to gently loosen up the engine. This works good for the electric start sleds too, so when you do give ‘er the juice it is easier to start.

Fresh winter fuel is also critical if you’re going to get any vaporization to occur. Old fuel or summer gas just won’t cut it. If this is your first ride of the year, then plan on getting fresh gas to get it started. Old gas doesn’t vaporize worth a darn at cold temps.

Anything you can do to warm the engine will also help. Sunlight, heated blanket, removing the battery and warming it, coolant heaters, block heaters, they’re all good. Oil selection becomes critical also, make sure your oil has a pour point well below the temps you’re in.

When you do get the engine loosened up and decide it’s time to start it, you want to spin it as fast as possible. This means robust pulls on the rope when you’re serious about getting it fired.

When the sled does fire, let it warm up until the cylinders are slightly warm to the touch. Be careful to not let it idle too long, it can over heat! Also be weary of slushy coolant, we’ve seen this happen at temps below –40.

Try very hard not to use things like starting fluid, you’re usually far better off (safer) to just warm the sled up somehow. A dry set of plugs work better than a frosty set or wet ones, so remember the basics of strong spark, atomized fuel and compression to get it going. You can wet the plugs easily with raw fuel and go from needing choke to being flooded.

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