or "roll starting"...whatever you want to call it.

anybody have any ideas on how to do it? It's been driving me insane ever since I got the truck.

Automatic - forget it.

Manual of any kind: Shift into highest available gear (if a 5-speed, then "5" ), turn the key to run, push in the clutch. Get a push or start rolling. When you're going 5-10 mph gently engage the clutch.

If another vehicle is pushing, let them get you up to 5-10, then have them STOP. Don't let them be on your bumper when you let the clutch out.

[This message has been edited by CanyonAg77 (edited 2/22/2007 2:32p).]

Why the highest gear? I hadnt heard that one before (and have always just used 1st).

Least stress on the transmission. In non-overdrive transmissions, high gear is 1:1. So when push starting, you are trying to turn the engine once for every one time the driveshaft turns, or about 3 times for every time the tires turn.

In low, you are overdriving the engine, turning it about 3 times for every one time the driveshaft turns, about 9 times for every wheel revolution.

Canyon, I respectfully disagree on using 5th. I'd think you'd want to be turning the engine at least close to idle rpms. 5mph in 1st gear would put you in that ballpark. 5th gear would not.

Don't forget to put the key in the "run" position.

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anybody have any ideas on how to do it? It's been driving me insane ever since I got the truck.

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Why have you been dying to try this?

http://www.4lo.com/calc/gearratio.htm
According to this calculator, 3.73 gears, 30" tires, 5th gear (.73 ratio) in the LD GM 5-speed (NV3500), and 5mph would net 152rpms. 1st gear (4.02 ratio) would net 839.

yeah, I was gonna say I don't think it would turn over in 5th gear.

i was always told to do it in 2nd.

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i was always told to do it in 2nd.

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I've always done it in second gear as well.

Hey, they are your transmissions. I've only been doing this sort of thing for 40 years.



Trust me, 5th gear will be plenty fast. Your starter does NOT turn the engine at idle speed. It turns it at 100-200 rpm max.

In the old days (before my time) lots of vehicles hand cranked. Do you think great-grandpa was turning that model T 1000 rpm?

It is not speed of cranking. If you have spark, compression and proper fuel/air, you can start at 20-30 rpm.

In fact, find a farmer with an old John Deere tractor (from 1923 to 1963) . He can show you how to set it up and start by flicking the flywheel about 1/4 turn at maybe 10 rpm.

you misunderstood...and apparently take me for an idiot

I'm not looking for the procedure to push start a vehicle...I know how to do that very, very well...

I'm trying to find out how to push start a 2002 Silverado. Which seems to be a little more difficult with some sort of "security" feature.

After rolling, with the key in "on" and upon letting the clutch out, the word "security" flashes on the info center screen and the truck fails to start.

How do I make the computer not care that the starter isn't being used to crank the engine?

From reading on the Internet apparently there is a "Clutch Start Switch" that is behind the clutch pedal that keeps it from starting if the clutch isn't depressed.

I assume it's something similar to the switch behind the brake in an automatic that keeps you from shifting out of park unless the brake is depressed.

I wonder if you could tape that switch and see if that worked?

The best way to handle this problem is to get a new reliable car.

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Hey, they are your transmissions.

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Well, if the tranny can't take the stress of turning the engine over at 800 rpms, then it likely would've failed the next time you tried to accelerate at a brisk pace or move a load anyway.

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Trust me, 5th gear will be plenty fast. Your starter does NOT turn the engine at idle speed. It turns it at 100-200 rpm max.

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This is probably true. Every time I've ever done it though, I've had a dead battery and usually some unrelated problem that is causing hard starting which resulted in a run down battery.

In these cases, I always found it easier to start with the higher rpm, likely for 2 reasons:
1) turning the engine over quicker clears any fuel flooding that may have occured and
2) turning the engine over quicker gets more output from the alternator helping the ignition system get more spark than it would've from the run down battery.

When you push start in 5th, what happens once the engine fires? Seems like you'd have crazy vibrations and maybe even knocking as soon as the engine was running in overdrive at 5mph. Do you have to stab the clutch back in as soon as it's starting to fire?


[This message has been edited by F W ag 01 (edited 2/22/2007 10:01p).]

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From reading on the Internet apparently there is a "Clutch Start Switch" that is behind the clutch pedal that keeps it from starting if the clutch isn't depressed.

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That usually just keeps the starter from engaging without the clutch pushed in. It shouldn't do anything to keep you from push starting.

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Well, if the tranny can't take the stress of turning the engine over at 800 rpms

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The difference is the way the stresses are applied: Backwards. In normal operation, a trans in 1st gear is taking 800 rpm and translating it out the back at say 200 rpm, a 4:1 reduction.

Go the other way, and you are asking the transmission to accept stress from the opposite end that it's designed to take stress and overdrive the engine at 1:4.

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When you push start in 5th, what happens once the engine fires? Seems like you'd have crazy vibrations and maybe even knocking as soon as the engine was running in overdrive at 5mph. Do you have to stab the clutch back in as soon as it's starting to fire?

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Yes, you do. In fact, most of the time I've done this type of thing, I've been pulling the dead vehicle with a chain, instead of pushing. So you darn sure better hit the clutch as soon as it fires, else you'll be climbing the tailgate of the tow vehicle.

I forgot this step, though clutching as soon as it starts is something I always do.

Another reason for high gear start that I just recalled: Occasionally I have been in on one of these deals where the towee tries to use a low gear. The usual result is that the back tires just lock and skid. That's got to be hard on the drivetrain, but I've luckily never broken anything.

Why does it skid? Look at it this way. If it takes 5 horsepower to spin your dead engine, when you overdrive it by starting in first with that 1:4 ratio I was talking about, now it takes 20 horsepower to spin it.

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I'm trying to find out how to push start a 2002 Silverado. Which seems to be a little more difficult with some sort of "security" feature.

After rolling, with the key in "on" and upon letting the clutch out, the word "security" flashes on the info center screen and the truck fails to start.

How do I make the computer not care that the starter isn't being used to crank the engine?

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Aha! That's the VATS (Vehicle Anti Theft System). Anytime you see the SECURITY light flashing, you've done something VATS doesn't like.

VATS requires that the key with the magnetic encoding be in the ignition before the truck will start. If you go to a locksmith and have a key cut, that key won't start your truck because it doesn't have the correct magnetic encoding. You have to go to a dealer and get raped for a second key.

Anyway the system, makes it more difficult for someone to bust your column, trip the ignition switch, and get your truck started. Without doing something to fool the VATS into thinking the right key is present, it ain't going nowhere. I'm guessing VATS requires not only for the key to be present but also in the START position instead of RUN.

Try push starting it while holding the key in the start position the whole time. Be sure and engage it into start before the pushing begins to avoid having the starter gear grind the flywheel if it tries to engage once the engine is turning.

VATS also requires that either the magnetic encoded key or keyless entry be used to unlock power doors. You'll notice if you lock the doors with the window down and you outside, then reach through the open window and manually unlock the door, then open the door the horn will begin sounding and lights flashing. Likewise, this is what would happen if a theif broke the window and reached inside to unlock the door.

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The difference is the way the stresses are applied: Backwards.

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Anytime you use the engine for braking, where the drivetrain was forcing the engine to turn 800rpms more than idle, then it's seeing this kind of force. Let off the gas in first gear at 10mph, and the tranny is seeing comparable stress.

If your tranny breaks push starting at 5mph, it was going to break during that drive anyway.

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Try push starting it while holding the key in the start position the whole time. Be sure and engage it into start before the pushing begins to avoid having the starter gear grind the flywheel if it tries to engage once the engine is turning.

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I'm glad somebody else thought of this because it makes it the obvious solution...but no dice...

My guess is that the computer knows the truck is rolling (from the speedometer input) and doesn't allow it to start.

VATS != security system...I have no horn and lights scenario...manual locks and manual windows...no remote unlock...

in 1998 this truck would be classified as a W/T.

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My guess is that the computer knows the truck is rolling (from the speedometer input) and doesn't allow it to start.

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That may be the case. I'm stumped.

Bad clutch switch?

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That may be the case. I'm stumped.

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Dang, i was afraid of that...maybe someday...

There should be some kind of a clutch safety switch, so it knows when you have the clutch in or out. Solely a safety feature. If you can disconnect or affix that switch(I don't know where it is) so that it thinks the clutch is in when it is in fact out, then you'll be golden.

Automatics have a similar type of switch. If you take that switch out or bypass it in some way, the computer thinks it's in park all the time, so you can start in gear, push start, etc.

and btw, the computer knows the truck is rolling, but this with a combination of the clutch being out is what's causing it to not start, or so I would assume. Otherwise, if for some reason, you're rolling down a hill with no brakes and the engine not running, you wouldn't be able to get the engine started under normal circumstances. THAT in itself would be dangerous.

hth

Can we get back to how to roll start an automatic? I've never seen it done.

Check your owners manual. I don't think autos can be pushed to start. All the pumps that supply pressure to the shift bands, etc. are run from the engine end. There are some rare exceptions, but I don't think they include modern cars/trucks.

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and btw, the computer knows the truck is rolling, but this with a combination of the clutch being out is what's causing it to not start, or so I would assume.

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Not sure about this.

VATS has 2 methods of disabling the vehicle - it disables the starter and it disables the fuel pump and injectors. When he's push starting the truck, he's not using the starter. The only reason it won't start is because VATS is disabling the truck by killing the fuel injectors.

Having the clutch engaged with the key in the run position and the vehicle moving shouldn't cause VATS to freak out and kill the injectors. If that were the case, the truck would never be operable, since that's the condition of everything anytime you're headed down the road.

At any rate, it's probably easier to just diagnose and fix the no-start condition than try to figure out why VATS won't let you push start and defeat that. Unless those two things are related...

Rebel, what happens when the truck won't start in the first place? Does the security light come on then? If you have a problem with the VATS module, where it incorrectly thinks the correct key isn't present, it'll disable the starter and the fuel injectors. So subsequent push starting won't help.

[This message has been edited by F W ag 01 (edited 2/24/2007 11:57a).]

He's right on as far as fixing the problem. You're push starting a 5 year old truck? I can see this at 10 or more years, but if you're needing to push start it regularly, fix it or ditch it.

As far as the VATS is concerned, I'm not sure about anything. I'm just saying that Chevrolet would want the truck to be able to start if the brakes would fail and the vehicle were rolling down a hill. Therefore you would have to push the clutch in and hit the key to start. By that reasoning, if you fool the switch(wherever it is) into thinking the clutch is in when it really is not, then you should be able to push start it. I am by no means an expert in this department.

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Can we get back to how to roll start an automatic? I've never seen it done

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I've only seen it once, never done it. Once again, I do prefer to fix them as opposed to Aggie engineering them whenever possible. It was an older model Chevrolet truck, maybe an 82 model 3/4 ton. The guy disconnected a safety switch and looped a wire across the connector so that the truck could be started in gear. He had some kind of a problem within the tranny towhere he couldn't put it in park and that fixed his problem. As a side effect, he could also push start it due to his modification. I never push started him, he just boasted about it and his mechanical capabilities. I would say in his case it is less genius/capabilities and more along the lines of white trash breeding that caused him an involuntary mental need to be able to push start his truck, kind of like Joe Dirt's face hair grew in all white trashy.
I'm not sure how this would be done in a modern automatic transmission. I'm sure it would take a lot more than that, but it could be as simple as removing the safety switch and engaging it permanently. It could be as difficult as rerunning new electronics around this switch. I'm just saying it can be done.

[This message has been edited by TheBANDIT (edited 2/24/2007 12:26p).]

That doesn't really make sense, Bandit. Push starting an auto is a function of pumps working, not switches. Just because he wired across the neutral safety safety switch didn't mean he could push start.

BTW, if he physically could not get the trans into park, he still should have been able to start in neutral, without bypassing the switch.

I'm not trying to be controversial here. That's just what the redneck told me. I did see that he could start it in gear. Aside from that, I have no proof that the push start function worked or did not.

Come on guys...it's a Chevy, there's no problem with it...

I just got lazy on day while parked on a hill, stuck the key in "on" and pressed the clutch...got it rolling, let the clutch out, and nothing but a flashing "security" light.

Been trying to figure out a way to push start it ever since (without trying anything stupid of course)...just in case...one day I go out to start 'er up and the 5 yr old battery decided to expire.

Is there any way to reprogram the main computer to not care anymore? My next guess is to get fed up with the mess, gut the truck and replace the internals with something carbuerated...that sounds more fun anyway.

Why the Angry Face? I wasn't doubting you related the story as it was told you. I agree, one can (stupidly) short across the NSS. I just wonder if he ever tried starting in neutral, rather than park. I'd bet he did not, else he wouldn't have gone through the shorting-out process.

I also highly doubt that you can push start a modern auto. A quick Google search implies that some autos up through the 60s (like a Chevy powerglide) could be push-started, but I don't think modern ones can be.

Just to add to the story...

it may not count as "push starting", but I was traveling 6 in my 1977 C10 one day a few years back and the Tach wire hit the exhaust manifolds, which burned off the insulation and grounded out the distributor.

having an engine cut out at 70 miles an hour is a pretty strange feeling...especially when suddenly you can hear the radio and the vehilces next to you and all...

but anyway...while trying things from the cab I reached down and grabbed the tach wire (aftermarket tach) gave it a good yank and managed to pull it off of the manifold. The spark kicked back in and the truck fired back up.

I must note though...this particular transmission is the locking type of TH350. Since I was going 70, the transmission probably stayed locked up in 3rd (direct) so there were no friction disks in between input and output.

If that's the case, I don't know how you would accomplish this from a standing start.

If the engine is already running, the front pump is running, providing pressure and the trans is all locked up. Thus, when the engine lost power, the trans still had pressure, all the gears were shifted and stayed shifted. Thus the driveshaft continued to turn the engine. If you had shifted into neutral, let the engine run down to 0 rpm, then shifted back into gear...it would not have worked, since the pump is in the front end.