starter motor difference

28th September 2013, 02:12

Does the starter motor from a diesel need more power from the battery then a petrol engine one ? And if yes, could fitting them th wrong way round be the cause of multiple need batteries dying, in light of the alternator being fine?

28th September 2013, 05:31

Diesel starter motors draw much more power from the battery than a petrol, as diesel engines have a high compression ratio. Whereas a petrol engine is much easier to rotate so less torque/power is required from a petrol starter motor.

So to answer your question a diesel starter motor will drain your battery much faster, especially if the car is used for short journeys where the alternator doesn't get much of a chance to re-charge the battery

28th September 2013, 08:29

Diesel starters are geared down, so they dont take any more to turn over, its the glow plugs that will suck power from a battery, and if theyre dead itll be a bugger to start.

28th September 2013, 16:28

Quote:

Originally Posted by welshpug

Diesel starters are geared down, so they dont take any more to turn over, its the glow plugs that will suck power from a battery, and if theyre dead itll be a bugger to start.

im not sure who to go with!

what do you means by geared down? i have read that you should let a diesel engine sit on the second click in the ignition for a while to warm the Gplugs or just turn it over for a while?

28th September 2013, 17:21

he means they are geared so the same force of turning can spin the higher compression over

28th September 2013, 18:46

indeed, whereas petrol units are direct drive.

is your battery warning light working properly?

28th September 2013, 18:47

The TUD5/TUD3 starter motors are not geared down. The diesel starter motors are the same as the ones fitted to a TU5 (8v or 16v).

So, the starter motor from a 1.5D, fitted to a VTR wouldn't draw any more current than a "VTR" starter motor. Nor would it turn the engine over slower.

Diesel ENGINES are harder to start due to huge current draw for the glow plugs followed by turning over high compression.

You have a current leak, or the alternator isn't charging correctly due to bad connections etc or a slipping belt under load.

28th September 2013, 19:31

The starters are no different.
Your battery going flat may be down to an aftermarket stereo or something like that.

With the car running check on the battery with the multimeter, should read about 14.6V. may well just be a lame alternator.

28th September 2013, 20:09

Or even a dud alternator sapping power from the battery.

28th September 2013, 21:04

Quote:

Originally Posted by welshpug

indeed, whereas petrol units are direct drive.

is your battery warning light working properly?

Nope, no light on my dash

And the alternator puts out 14.1v with everything bar the rear windscreen heater on. Belt slipping , how can I test this ?

Also, this past summer, drove twice a day, 12 miles either way. If the alternator was dud, it should have failed me at least once . There is a 0.14a draw but on the f8 fuse (interior fuse) but that's exactly the same as from a couple of other saxos WHICH DON'T KILL BATTERIES. Baffled!

28th September 2013, 21:43

Quote:

Originally Posted by ns9900

Nope, no light on my dash

And the alternator puts out 14.1v with everything bar the rear windscreen heater on. Belt slipping , how can I test this ?

Also, this past summer, drove twice a day, 12 miles either way. If the alternator was dud, it should have failed me at least once . There is a 0.14a draw but on the f8 fuse (interior fuse) but that's exactly the same as from a couple of other saxos WHICH DON'T KILL BATTERIES. Baffled!

Maybe you have a crap battery that's starting to sulfate? So with your small current draw it's killing it off?

29th September 2013, 00:01

Yes diesel starter motors have reduction gears but I haven't seen one that doesn't draw more power compared to a petrol. For example I work for a Volvo specialist and the S40 2.0D starter uses 2.2Kw power whereas the petrol 2.0 s40 starter uses 1.2kw.

Also just checked with ECP and the saxo vtr 1.6 petrol starter uses 0.7-0.9kw but the 1.5d starter uses 1.4kw, a totally different rating and they will work and fit the same but in the long run will cause issues like you have now, take what you want from it.....check yourself, im not lying to you

29th September 2013, 00:02

they all fit iirc. i've got a 1.4? one off a 106 roland on mine atm.. as i ruined mine months ago when had the fueling/pump/injector issue (on off/start) With the 106 starter, it starts up as good as my orig one did.

orig gave the ghost up lastnight

29th September 2013, 18:17

Quote:

Originally Posted by SnakeVTR

Yes diesel starter motors have reduction gears but I haven't seen one that doesn't draw more power compared to a petrol. For example I work for a Volvo specialist and the S40 2.0D starter uses 2.2Kw power whereas the petrol 2.0 s40 starter uses 1.2kw.

Also just checked with ECP and the saxo vtr 1.6 petrol starter uses 0.7-0.9kw but the 1.5d starter uses 1.4kw, a totally different rating and they will work and fit the same but in the long run will cause issues like you have now, take what you want from it.....check yourself, im not lying to you

Regardless, a motor will only draw what power it needs to turn the engine over. even if the ratings are higher, that's a maximum output. This means if you fit a 1.5D starter to a petrol that's okay. but not the other way about.

If your engine needs 0.6KW to start, the motor will only draw 0.6KW considering that both the motors have the same number of teeth and the same fitment. I think it's 9 teeth - it's 9 teeth on my 1.5D starter.

ECP is hardly a reliable source? isn't that the company that supplies tapered driveshafts for pre1999 saxos and 106s? oh yes. And the same place that ordered the wrong wheel bearing for me, twice in a row. then had to supply me a C2 wheel bearing because "we can't get 106 GTi wheels bearings". //end ECP rant.

29th September 2013, 19:44

Quote:

Originally Posted by MartinObviously

Regardless, a motor will only draw what power it needs to turn the engine over. even if the ratings are higher, that's a maximum output. This means if you fit a 1.5D starter to a petrol that's okay. but not the other way about.

If your engine needs 0.6KW to start, the motor will only draw 0.6KW considering that both the motors have the same number of teeth and the same fitment. I think it's 9 teeth - it's 9 teeth on my 1.5D starter.

ECP is hardly a reliable source? isn't that the company that supplies tapered driveshafts for pre1999 saxos and 106s? oh yes. And the same place that ordered the wrong wheel bearing for me, twice in a row. then had to supply me a C2 wheel bearing because "we can't get 106 GTi wheels bearings". //end ECP rant.

The motor doesn't get to choose how much power it consumes, regardless of what engine its fitted to it will still draw the same power as it is rated to, as this is the power needed to work the motor.

If a under rated starter is fitted to an high compression diesel engine the motor wont draw any more or less power than its rated, it just wont turn the engine over fast enough and more than likely burn the motor out because it cant use the power its drawing

"ECP is hardly a reliable source?"....... Depends who you speak to

29th September 2013, 21:12

Quote:

Originally Posted by SnakeVTR

The motor doesn't get to choose how much power it consumes, regardless of what engine its fitted to it will still draw the same power as it is rated to, as this is the power needed to work the motor.

If a under rated starter is fitted to an high compression diesel engine the motor wont draw any more or less power than its rated, it just wont turn the engine over fast enough and more than likely burn the motor out because it cant use the power its drawing

"ECP is hardly a reliable source?"....... Depends who you speak to

Let me repeat what I said, but worded differently.

If your engine requires 0.6 KW to start, and you fit a 0.8KW motor. the motor will only draw what load is put on it i.e 0.6KW.

If you fit a 1.4KW motor, and the load you put on it is 0.6KW, it will only draw 0.6KW.

A 1.4KW motor, unloaded just spinning on its own, isn't drawing it's rated power.

The rating of the motor, is the maximum average power it can consume safely. It can load more for short periods of time, or less for longer periods.

so you're right, the motor doesn't choose what power it consumes, the load put on the motor decides.

I said, in my previous post that fitting the 0.8KW motor to the diesel WON'T work.

Thank you and good night.

30th September 2013, 02:25

Another one issue, considering terminals and battery checks out , is a bad starter motor? Maybe worn parts causing no turn over ?
I'm told that a battery reading 11.8v is fine but for me, sub 12 is when it don't turn over...

Surely bad internals means the normal rate of power sent won't suffice as there is more resistance

30th September 2013, 18:23

Quote:

Originally Posted by ns9900

Another one issue, considering terminals and battery checks out , is a bad starter motor? Maybe worn parts causing no turn over ?
I'm told that a battery reading 11.8v is fine but for me, sub 12 is when it don't turn over...

Surely bad internals means the normal rate of power sent won't suffice as there is more resistance

No way 11.8 is fine.

12.8 is fine
12.7 is okay
12.6 is starting to wear out and age.

consistently less than 12v after a drive and settling time would indicate a battery that is starting to Sulfate.

That's what gives you that internal resistance.

1st October 2013, 01:06

It reads 12.6v+ for 2 days after a long drive. Day three however it drops to sub 12... Spoke to a Citroen mechanic and he said that the srs circuit , if not complete, up to 5a of current can be drawn from the battery even if the car is sitting doing squat. Testing the theory atm and will update in a few days! Thanks for the help thus far, if anyone has any opinions , just lay it down in case I come back unsuccessful :o

3rd October 2013, 20:51

updated, battery still died. gonna get auto electrician to check the earths. aside from those in this quote, are there any others?

Quote:

Originally Posted by Mochachino

Check the circuit between the alternator, starter motor, and the earth on the gearbox. You have 2 earths on the gearbox, one quite thick and a small thinner one coming from the main loom.

One on the inner strut behind the drivers light area. And one behind the battery underneath the large fuses.

Checked there isnt somthing live overnight when it should be switched off, or you just need a new battery?

3rd October 2013, 20:55

alternator could be knackered if the batterys dead

4th October 2013, 14:21

na, i've had it load tested by a couple of mechanics and all have come back showing 14.1v unless you put the rear screen heaters on. :/