I can't believe I'v never thought how this worked. Does anybody know EXACTLY how dropping the clutch while moving starts the engine?

 

well what i would assume is it forces the motor to turn over, thus creating combustion in the chambers, thus starting the truck/car/bike...only possible on a carbureated motor tho...atleast i would think

 

Oh its possible with a FI engine, but is easier on a carb...

Basically put the car in 1st or 2nd, then push the clutch in and make sure its being pushed decently..your gonna need a bit of space to do this. As your being pushed and gain speed you dump or release the clutch and quickly get on the gas..takes practice..

 

Well...

All the starter motor does is get the engine turning over, after that the distributor turns, fires the plugs, ignites the mixture, and the engine sustains itself.

When you do the push starting trick (and generally it's easing the clutch out quickly but evenly), it's simply using the wheels and drivetrain to accomplish the same thing, i.e. turning the engine over. Assuming everything is in good tune, the engine should continue to run on it's own after it's been given the initial spin.

It's gotten my butt out of a couple bad situations.

 

It works on my EFI, some engines have a switch that needs tripped, before you can push start. Or, maybe it's before you can start it in gear? I dunno, my truck does both.

 

The engine doesn't care what turns it over. A starter motor, a crank, a shotgun shell, a pull cord or momentum through the driveshaft and clutch all contribute the same thing. If there's fuel and spark after that, it will start.

 

i retract my statement, i thought it thru more and understand now

 

i guess your sol if you have a auto ?

 

The starter spins the flywheel which in turn spins the crank. This creates compression in the cylinders. Meanwhile, assuming you have "some" battery, you will be getting spark and fuel in the cylinders, causing the engine to start. Starters take alot of juice, even more on diesels, which is why they usually have 2 batteries.

 

The alternator gets spinning when the clutch engages, thus sparkola. Battery only starts starter. Not needed when alternator starts movin'.

 

Pretty much...course you could figure out someway to do it. Engine just needs to turn over somehow.

On a related note, I once actually had to use the egg repair trick on a radiator will at a remote campsite some years ago...it worked and held till I could get a new one a week later.

 

Ahhhh, we need to clear up a missunderstanding here.

See, the EFI thing has to do with the reason one would want to roll start, or push start, a vehicle.

With a carb, it is possible to do it anytime, with not much of a hill. EFI actually takes only a little farther.

The reason is that one of the main reasons for this trick is if you happen to be near a hill, and your battery is dead, from, say, leaving your lights on. A carbed truck will need just enough speed to turn over the engine, and PRESTO, started.

Its possible to do it with an EFI truck, but you actually do need SLIGHTLY more juice to get the electronics to run. This is only going to be a problem with a REALLY dead battery.

But yeah, i drive a fuel injected beast, and have done it before several times.

 

The alternator produces enough juice at 1-10 rpm's to create spark? Cool.

 

okay, everyone else posts like 400 posts while i'm working on that one, and you've already answered the question. dang it.

 

Yes your SOL with and Auto.... When you shut the key off in drive the transmission ECU assumes that something is wrong and will shift into neutral.
(at least thats how I perceive it, but I could be wrong)
It my be a feature in an auto transmission to save it, like I noticed once, I like to shift into neutral and roll to a stop before I put it in reverse, well I went past it once and straight into reverse, the engine quit and the trans switched to Neutral (granted this was at a high speed) at lower speeds when I switch it into reverse from Neutral the trans remains in Neutral until it is either slow enough or at a stop to engage reverse. Sorta like if you take it from drive at 50 and shift into first, the auto trans will wait till the vehicle is at a low enough speed to switch. An auto trans is meant to think for itself (I hope this all makes sense, cause I am dead tired and I don't think I even made sense so someone please feel free to correct me...)

 

I think you're close Yotafun, and I retract my previous statement. It makes no sense because the torque converter can't transfer any torque without a running engine/pump. Right?

 

That answers my question. Dare I ask another?

So can you take the battery out once the engine is running, and have it still run?

 

Assuming the alternator is in working condition, yes. Most of the power is drawn from the alternator during operation.

EDIT: I wouldn't recommend doing it though, due to power running through the cables and them then being loose in the bay. Why would you want to do it anyways?

 

Yes, I have actually done this myself.

The battery is just to get the starter running or to use the radio and such when the ignition is turned to the ACC position. and even then the radio is the only thing that works when the key is in that position.

The alternator can take care for the rest IIRC

 

Yea, with an auto it may be impossible..I dont know for sure.

One time I wanted to see if I could still steer the car if I shut the engine off and had shifted into N. In my 93 camry the answer is NO...it locks the dang wheel with no engine! Maybe it was me, I only did it once and it was downrightscary..

Now my friends dodge avenger it didnt matter, he lost all power and was fine to steer.