nickwilliams Posted November 27, 2011 Share Posted November 27, 2011 When starting my 300TDi from cold, I find I need to 'blip' the throttle to get the revs above about 1250 rpm briefly before the charge warning light goes out. Once the light has gone out it stays out when the engine drops to idle. Once it's warm there isn't a problem. Idle speed when cold is about 650rpm and increases to about 850 when the engine has warmed up. The S belt is less than 2000 miles old and the tensioner is working correctly. There are no squeaking or squealing noises. Is this an indication of imminent failure of the alternator or is it a belt related problem after all? Nick. Quote Link to comment Share on other sites More sharing options...
Puffernutter Posted November 27, 2011 Share Posted November 27, 2011 This isn't a problem! Mine does exactly the same. It's just a case of needing to get sufficient current from the alternator to make it self excite. I suspect when all is warm, resistances may be slightly lower (friction and electrical), plus the fact the battery will be better charged. Cheers Peter Quote Link to comment Share on other sites More sharing options...
ejparrott Posted November 27, 2011 Share Posted November 27, 2011 my 200 does the same! Quote Link to comment Share on other sites More sharing options...
nickwilliams Posted November 27, 2011 Author Share Posted November 27, 2011 Well, it seems unlikely that they left the factory like that so it would be interesting to know what the cure is.... Quote Link to comment Share on other sites More sharing options...
Puffernutter Posted November 27, 2011 Share Posted November 27, 2011 The charging light is in the circuit of the field coil and provides current to start the excitation process off. I suspect when all is cold and the battery has been discharged to start the car, the rpm required to generate enough current to self excite is more than when everything is warm/hot. I imagine that they do leave the factory like that! Cheers Peter Quote Link to comment Share on other sites More sharing options...
western Posted November 27, 2011 Share Posted November 27, 2011 Tdi idle should be between 750 to 800rpm, 650 is to low. reset the idle rpm, my 200tdi charge light goes out straight after start. Quote Link to comment Share on other sites More sharing options...
TSD Posted November 27, 2011 Share Posted November 27, 2011 Don't know if whole vehicles leave the factory like that, but it's not a fault as such. It indicates the current through the warning light circuit is insufficient to kick the regulator (and hence the alternator) into operation. When you blip the throttle, you force the alternator into self-excitation (fnarr). You could try a higher wattage bulb in the warning light (if they exist in that size) or a resistor (or another bulb) in parallel with the warning light. On the other hand, mines been like that for 140k (was a new crate TGV) and I've yet to get around to it Quote Link to comment Share on other sites More sharing options...
Range Rover Blues Posted November 27, 2011 Share Posted November 27, 2011 If it really bugs you, strip the alternator, clean out the brushbox and fit new brushes for the field coils. Chances are they have workn and are sat in their own dust making them stiff, so the resistance of the field coil is effectively higher. Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted November 27, 2011 Share Posted November 27, 2011 All three of mine do it, has never really bothered me enough to do anything about it though. Quote Link to comment Share on other sites More sharing options...
Dads Toy Posted November 28, 2011 Share Posted November 28, 2011 Reassuring to know that mine is the same as a lot of others - and stopped me worrying about it. Quote Link to comment Share on other sites More sharing options...
rusty_wingnut Posted November 28, 2011 Share Posted November 28, 2011 mine did it for years Quote Link to comment Share on other sites More sharing options...
thinfourth Posted November 28, 2011 Share Posted November 28, 2011 Don't do as i have done. Have a flat battery and jump start the landrover, leave it running for 10 minutes at idle while you pack away the jump leads and then wander out of the car park and housing estate at idle. Get to the main road and stall, discover that you have put zero charge into the battery and walk back to get the jumps leads and other car to start it again. Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted November 28, 2011 Share Posted November 28, 2011 And do remember that if your bulb fails the alternator will not excite until you rev the engine to 3000 rpm or so. I carry a spare bulb just in case! Quote Link to comment Share on other sites More sharing options...
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