Does this Car Push/Roll Start?

[FRSBRZGT86FAN]

Originally Posted by mdm

Without researching it any more, I'd theorize the following scenario.

During Several unsuccessful attempts at push-start the air-fuel mixture flows through the engine and fuel is collected in cold cat. When the engine ultimately starts, the cat heats up, and suddenly you have a significant amount of fuel in the presence of very hot catalysts, and things get nasty.

One thing that my brilliant theory does not explain, is why things would be any different if a few unsuccessful starts using the starter are followed by successful start.

That literally is not how it works, the cat stays cold it takes quite some time for it to warm up, so much so any unburnt fuel will ignite in the exhaust regardless by that time or just get sent into the atmosphere, if it does nothing dangerous will happen it's contained. People are actively creating tunes to do this by retarding ignition timing off throttle to get there exhausts to crackle and pop.

[thomasmryan]

I like the bearings to have a supply of oil before loading the crank with the drivetrain.

I will not jump or be jumped on any car with a computer.

Charging a disconnected battery or just purchase a new one if it has issues, is the preferred route for me. Bad batteries kill alternators. Bad alternators kill batteries.

There is a sticker on your window for a number to call if you have a dead battery. Most manufactures do this for free.

[Ultramaroon]

Originally Posted by thomasmryan

Bad batteries kill alternators. Bad alternators kill batteries.

There's a shred of truth to this but you haven't supported any of your wide swath of assertions. If you care to explain your reasoning, I promise I'll be civil with my responses.

[WNDSRFR]

Originally Posted by Ryguystye

In the event of the battery being too low to start normally, can I start this car with a push/roll? Or do the modern ignition and fuel systems require me to use jumper cables?

Yes you can. Regardless of all the overcomplicatation put forth is this discussion.

Just turn the key on, put the gearshift into 2nd, engage the clutch, get rolling to a reasonable speed, disengage the clutch, and the engine will start.

Unless you have an automatic transmission or a "push to start" miracle of modern technology.

Then WHY?

[billwot]

You cannot push-start a modern car if the battery is fully discharged.

If it is fully discharged, you have no power to the ECU, no powerto the the FP, no power to the injectors, and no power for ignition.

All of those systems/devices are required to start the engine.

[thomasmryan]

Ultra...

Say your voltage regulator is bad and puts out 17volts, it won't take long for the electrolyte to gas off or heat up the battery to the point of swelling, ect.

In the other scenario, assume you have a dead cell or a cell low on electrolyte. Your voltage regulator will keep allowing higher and higher amounts of exciter current to try to get the lame battery up to voltage...which never happens because of the dead or weak cell.

[thomasmryan]

When one downshifts in a not so smooth fashion, these little springs are being pushed instead of being pulled.

I equate that to roll starting where the clutch is the driving force instead of what is being driven.

[FRSBRZGT86FAN]

Originally Posted by thomasmryan

I like the bearings to have a supply of oil before loading the crank with the drivetrain.

I will not jump or be jumped on any car with a computer.

Charging a disconnected battery or just purchase a new one if it has issues, is the preferred route for me. Bad batteries kill alternators. Bad alternators kill batteries.

There is a sticker on your window for a number to call if you have a dead battery. Most manufactures do this for free.

There is a sticker on your window for a number to call if you have a dead battery. Most manufactures do this for free.


Roadside assistance? This is not free, AAA in my case requires a yearly renewal of subscription fees.....

Bad batteries kill alternators. Bad alternators kill batteries.


Second part is true first part isn't always true, if you jump the car incorrectly you can totally destroy an alternator though. If there is a dead cell in the battery, it will though cause extra heat in the alternator lessening it's life cycle. As long as you replace it quickly enough that it doesn't keep trying to overcharge that dead cell you're fine. If you do something stupid like leave the lights on a car with a new battery you're for the most part fine....

I like the bearings to have a supply of oil before loading the crank with the drivetrain

What? Turning the engine over is a heavy load as well, and if anything a load has to be applied to get the oil pump to start moving oil to the valvetrain and bearings....

[FRSBRZGT86FAN]

Originally Posted by billwot

You cannot push-start a modern car if the battery is fully discharged.

If it is fully discharged, you have no power to the ECU, no powerto the the FP, no power to the injectors, and no power for ignition.

All of those systems/devices are required to start the engine.

This is an important assertion, it will only work if you have enough power for maybe when all the ignition lights and internal lights to appear dim

[Ultramaroon]

If you quote me I'll know you responded.

Originally Posted by thomasmryan

Ultra...

Say your voltage regulator is bad and puts out 17volts, it won't take long for the electrolyte to gas off or heat up the battery to the point of swelling, ect.

In the other scenario, assume you have a dead cell or a cell low on electrolyte. Your voltage regulator will keep allowing higher and higher amounts of exciter current to try to get the lame battery up to voltage...which never happens because of the dead or weak cell.

First part is true. Second part is true only in the case of a shorted cell. Not a common failure mode. My first gen Eclipse sucked at dealing with a deeply discharged battery. Regulator would take a dump every time. I finally modified my fourth alternator. Replaced the internal regulator with an external one from a Ford F150.

Originally Posted by thomasmryan

When one downshifts in a not so smooth fashion, these little springs are being pushed instead of being pulled.

I equate that to roll starting where the clutch is the driving force instead of what is being driven.

That's not going to hurt anything. They can handle it. Don't forget what's on the other side of the friction disc. It's the flywheel.

I'll hold off on the oil thing for now.

[MasonL1997]

You can definitely do it. Had to do it to my 86 last week after not being started for 2 months. Started it with a jump starter then drove somewhere. I sat in my car while dad went to the shops, had the radio going for 5 minutes and battery went flat. Got out, pushed, jumped in, pop clutch with ignition on and with a bit of jumping, boom she came into life.

[mdm]

Originally Posted by FRSBRZGT86FAN

That literally is not how it works, the cat stays cold it takes quite some time for it to warm up, so much so any unburnt fuel will ignite in the exhaust regardless by that time or just get sent into the atmosphere, if it does nothing dangerous will happen it's contained. People are actively creating tunes to do this by retarding ignition timing off throttle to get there exhausts to crackle and pop.

It would be interesting to know what is the rationale behind owner manuals discouraging push-starts.

[Ultramaroon]

Originally Posted by mdm

It would be interesting to know what is the rationale behind owner manuals discouraging push-starts.

I'm going to guess concerns of personal injury or property damage due to loss of control of the vehicle.

[Tcoat]

Originally Posted by mdm

It would be interesting to know what is the rationale behind owner manuals discouraging push-starts.

Originally Posted by Ultramaroon

I'm going to guess concerns of personal injury or property damage due to loss of control of the vehicle.

That and if you screw up too bad you can fuck the car up big time!