SWMBO has had to call out the breakdown services today.
She left her lights on in her Honda CRV and flattened the battery. Stupidly it does not have a lights on warning buzzer.
She was parked on a hill and _could_ have bump started it - but she did not know how, as she has not had an auto before.
It got me thinking. We have all had the ignition on, rolled down a hill in neutral, then popped it in to third. Hey presto! your manual car has started. (If it was a diesel it would keep going without any electrics at all day like this.....)
Anyway, how do you bump start an auto ?
I can't think....
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I accidentally switched my auto off because I got in the car funny, and banged my knee on the key in the ign, I remembered as the LED keyfob light flashed in the dark.
About 20 miles later, I was going round a bend and lost power, PAS and warning lights came up, and "Automatic Gearbox" on the display.
anyway, I was coasting along, and went to turn the key to try and restart, and as soon as I turned it it started, the starter didn't even engage as it was not in N or P. It had bump started.
I then tried this again another day, and sure enough at 30mph, it restarted. I have no idea though, if this was because it was already in D.
If it was in P or N maybe there would not be enough power to engage drive or maybe the hydraulics would have to be running first.
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I think thats imposible because the auto box works totally different, the auto clutch i dont think will work unless the engine is running!! Push it down a hill & puttin it in D might reck it i think?
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Its not what you drive, its how you drive it! :-)
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have heard this used to work years ago on older auto-boxes, i wouldn't try it on some newer stuff, actually make that any. new auto-boxes are expensive. renault espace box cost 3 grand to fix...cheers...keo.
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I think that modern auto boxes only have a hydraulic pump on the input shaft so bump starting isn't going to work.
Kevin...
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My W123 Merc had instructions in the handbook for bump starting - to my surprise.
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I thought bump starting was bad for the catalytic converter or oxygen sensor? But I suppose once, in an emergency, would be all right.
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Thats correct, father used to manage a fleet of 150 Mothers Pride BMC LD vans with 2.2 diesels and BW35 autos and they were twin pump and could be tow started and needed to be in the winter.
I didn't think modern boxes had twin pumps and towing it without knowing for sure could damage the box. Also towing or bumping cars with cambelts can jump the cambelt.
Jim
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well, you learn something everyday....my 1973 Escort had a BorgWarner type 35 auto box and I was under the impression that it could not be bump started...it was only a problem in winter when the starter motor could not turn the engine and a autobox due to the auto fluid becoming viscous.
StarGazer
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Essential kit for Auto drivers:
Heavy Duty jumper leads - none of those namby-pamby ones that you buy on special at the petrol station!
Page from owners' manual, on "how to jump start" - photocopied and enlarged, laminated, and kept in the bag with jump leads.
(You don't really want to ponce about finding the relevant page in the manual at 2am, with rain and wind lashing down, do you?
Oh, and it is dark, and you can't even SEE the writing...)
I've seen enough blokes ('I know what I'm doing') making mistakes when they jump-start cars... and on one particular Beemer, not reading TFM ended up frying a very expensive piece of electronic control unit...
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Essential kit for Auto drivers:
Page from owners' manual, on "how to jump start" - photocopied and enlarged, laminated, and kept in the bag with jump leads.
>>
Thanks for that tip. Will do.
I've seen enough blokes ('I know what I'm doing') making mistakes when they jump-start cars... and on one particular Beemer, not reading TFM ended up frying a very expensive piece of electronic control unit...
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It is worth noting that instructions vary from make to make of car as to what kit to switch ON - BEFORE disconnecting the leads.
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>> Thanks for that tip. Will do.
I posted something a while back on a similar vein ...
copying the fusebox layout, the tyre pressures, fluid requirement charts, adding telephone numbers of AA and insurers etc and laminating into one 'handy' sheet for use in emergencies.
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Not all BW35 were twin pump, these were specifically built for the commercial market, certainly other BW boxes I've had can't be bump started. Also the vans had to be doing circa 35MPH!
Used to be a good pocket money earner when I was a kid. Saturday morning in the winter lots of self-employed van owners wanting to get started and earn money. BIG jump batteries were tried first then if that failed get another van and rope and heave the thing round and round the yard until it started in a huge cloud of back smoke. Old deisels people don't know what they're missing ;-)
Jim
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I remember being surprised by my brother in law bump starting an big old automatic Wolseley by running it up to about 30 mph and sticking it into drive on a steep hill in Devon after it refused to start.I did not know you could do it.
On the subject of jump starts I always used to carry jump leads and a can of WD40 and would always offer to help anyone in distress.
These days I would not offer with any of the latest machinery. The chances of burning out expensive electrical components are too high.
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Unless the cars handbook specificaly states the car can be bump started.You cannot..If you are able to.Dont leave it in park when trying to move or severe damage will occur to Box... Neutral or Drive OK
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Steve
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I recall, in the early '70s, being towed around in a Mk3 Zephyr auto by the owner who had just fitted a recon engine, periodically whacking it into Drive.
How we didn't wreck the gearbox I'll never know, because it turned out he had fitted hugely oversized piston rings and it was, effectively, a seized lump.
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In a similar vein, I once had to tow a very rusty Fiat 600 that I had acquired for spares, it had lain rusting in a front garden for some time and all the drums were locked on.
Having towed it through the garden and onto the road, we managed to unlock 3 of the four drums, however the last one was an absolute pig - copious amounts of WD 40 and sweating did nothing.
It was decided to try a snatch technique by allowing a little slack in the tow rope at about 15-20 mph and then accelerating hard.
I was in the Fiat and it all went pear shaped when the 'little slack' became a huge loop that I had to brake to avoid running over - just as the tow car accelerated.
How I never crashed when the whole front of the Fiat came off and sailed up the road after my Renault 16 I'll never know. I was laughing so hard I hurt the next day.
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A pal of mine used to work as a taxi driver in a large northern town. All of the cabs used to carry jump leads, and cold mornings always resulted in phone calls asking for a jump start. A good little earner for the driver and cheap for the motorist. What happened to this sort of initiative ?
steve o mentioned gearbox damage if the car is towed whilst in park. I don't doubt that he's right, but many years ago whilst driving a Colt lancer fitted with a Chrysler auto box I accidentally selected park at about 20mph. There was a VERY loud ratcheting noise, and on the last 'click' the car lurched to a halt. No damage seemed to have been done, and the car drove perfectly afterwards.
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Also towing or bumping cars with cambelts can jump the cambelt. Jim
Never understood that bit. Starter motor turns flywheel and all the other bits of oily metal start moving until the motor's running (or not). Towing the car turns the road wheels which turns the gearbox which turns the flywheel which, as far as I can see imparts exactly the same motion to the oily bits in the engine. So why the risk to the cam belt?
Hawkeye
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Stranger in a strange land
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Starter motor churns away at 10's rpm a minute, bump starting a car
causes everything to go from 0-2000 rpm in fractions of a second.
Not unknown for a belt to jump when this happens, especially if it's less than new.
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When the engine fires, doesn't it go from 10 rpm to 2000 rpm in a split second too?
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I could get away from my parking place with just a small push to get to a good downhill stretch. Purely from curiosity I tried to see if getting Sonata auto rolling and switched on in D would do anything. It just rolls as in neutral, no turning of engine. I now have one of these mains charged startup gadgets, on the principle that what you have you never need.
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Thats because it only has a single pump driven by the engine, by rolling all you are doing is turning the output of the gearbox, hence no line pressure to engage a clutch or brake band.
As regards bump starting cars with cambelts I believe it is the sheer impact as you release the clutch that is the issue, in the days of race motors with Cambelts (BDA etc) then it was always a no-no.
Jim
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As regards bump starting cars with cambelts I believe it is the sheer impact as you release the clutch that is the issue, in the days of race motors with Cambelts (BDA etc) then it was always a no-no.
That's what I still don't understand. Surely exploding a petrol/air mixture in the cylinders and rocketing the revs from 0 to 2000 in half a second is quite a big impact also? Why doesn't that make the cambelt jump?
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