Can you bump start a new Diesel motor?

[MickL Addicted PP Member Find all posts View Profile Close MickL]

Re: Can you bump start a new Diesel motor?

So as to push starting D4D Prado .... if you have flattened your battery below that threshold you can push it all the way home and it won't start.

As long as the battery has enough life left in it to excite the field in the alternator once the engine rotates you'll have above ECU cut off voltage.


If your battery (assuming standart type lead acid) is down to 10.5 volts you have probably damaged it anyway, considering it's considered flat in the high 11's and fully charged at about 12.6 then 10.5 is pretty far gone.


Current surge and spikes from bump starting with a flat battery are right up there with mobile phones setting of airbags on the scale of risk. Cars have generally had EFI/ECU's since the mid 80's and the technology is pretty robust and reliable. People push/bump/tow start these vehicles all the time without a plague of blown up EFI systems being unleashed across the country.

Mick

[01Rod Junior Member Find all posts View Profile Close 01Rod]

Re: Can you bump start a new Diesel motor?

So as to push starting D4D Prado .... if you have flattened your battery below that threshold you can push it all the way home and it won't start.

As long as the battery has enough life left in it to excite the field in the alternator once the engine rotates you'll have above ECU cut off voltage.

Hey Mick... just remember most ECU's are now controlled by the cars ECU.. so most times the alternator will never excite without the threshold voltage..

If your battery (assuming standart type lead acid) is down to 10.5 volts you have probably damaged it anyway, considering it's considered flat in the high 11's and fully charged at about 12.6 then 10.5 is pretty far gone.

Most cars that have the lights left on, or doors left adjar or a load etc will have a static battery voltage of about 0.30v when you test it.. shut the doors turn off the headlights etc and leave the battery sit for a few hours and it will slowly start to recover, then you will see the static voltage no more than about 11.50v at the most after the vehicle has sat for a while with the loads off).

Current surge and spikes from bump starting with a flat battery are right up there with mobile phones setting of airbags on the scale of risk. Cars have generally had EFI/ECU's since the mid 80's and the technology is pretty robust and reliable. People push/bump/tow start these vehicles all the time without a plague of blown up EFI systems being unleashed across the country.

Mick

Mick, I work for one of the auto clubs, 5 years on the road as a patrolman, and now 4 years in a training and research role.... I can assure you we see approx 5 vehicles per week that have been damaged prior to our arrival, through either incorrect jump start or yes CLUTCH starting the vehicle....
The usual story is this.. "I had a flat battery so we push started(or Jump started) the car.. it ran for a bit then just stopped."
end result is a tow truck...

The other interesting thing is the number of "newer" cars that are sitting at the bottom of the hill where they have been rolled to the bottom.. trying to clutch start them.... no start due to the battery voltage..

I pass this info on not as a Theory but from what I have seen and still see everyday...

Rod