Torque Convertor lock up issue perhaps?

wammers said:

No because the regulator senses the battery voltage and adjusts the current in the field coils turning the alternator output up or down. A full charged battery will not receive a charge from the alternator but one that falls below say 12.5 volts will. 14.2 volts set point of the regulator is the maximum voltage that will be allowed to be put through the field coils and would give maximum output. This will vary, controlled by the regulator between 13.5 and 14.2 depending on the batteries state of charge and alternator charge rate needed. If the regulator had a set point above 14.2 which is regarded as the maximum charge rate for lead acid batteries, then yes it would boil the electrolite off in time.

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The regulator is a fixed voltage, it has no means of sensing battery voltage, current is limited by the potential difference between the battery voltage and the regulator voltage. Battery voltage at 12 volts, regulator at 14.2 =PD of 2.2 volts = maximum current from alternator. Battery voltage at 13.8 regulator at 14.2 = PD of 0.4 volts charge rate downs to a couple of amps or so. Battery apparent voltage at 14.2 regulator at 14.2 = PD of 0 volts which equals no charge. At all times the regulator is trying to maintain the output at 14.2 volts, whenever the load pulls the voltage down below the set point the current through the rotating field (armature) is increased in direct proportion thus increasing the available output current.

Datatek said:

The regulator is a fixed voltage, it has no means of sensing battery voltage, current is limited by the potential difference between the battery voltage and the regulator voltage. Battery voltage at 12 volts, regulator at 14.2 =PD of 2.2 volts = maximum current from alternator. Battery voltage at 13.8 regulator at 14.2 = PD of 0.4 volts charge rate downs to a couple of amps or so. Battery apparent voltage at 14.2 regulator at 14.2 = PD of 0 volts which equals no charge. At all times the regulator is trying to maintain the output at 14.2 volts, whenever the load pulls the voltage down below the set point the current through the rotating field (armature) is increased in direct proportion thus increasing the available output current.

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Think you have just written exactly the same thing i did but in a different way. An automotive alternator is not self exciting so can only work by the battery voltage being fed to the rotating field coils. As the battery voltage increases the voltage to the field coils is reduced by the regulator to reduce the alternator output and balance the charge rate. So whether you say sensed or compared by the regulator it amounts to the same thing.

wammers said:

Think you have just written exactly the same thing i did but in a different way. An automotive alternator is not self exciting so can only work by the battery voltage being fed to the rotating field coils. As the battery voltage increases the voltage to the field coils is reduced by the regulator to reduce the alternator output and balance the charge rate. So whether you say sensed or compared by the regulator it amounts to the same thing.

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The alternator provides all the current to the field via the diode pack and regulator. The battery is only needed to kick it off. The alternator will run quite happily with no battery once started although the output is a tad rough with no ballast. I used to use one to produce 3 phase AC which I stepped up to 110 volts with a transformer. The residual magnetism in the field was enough to start it, no battery used at any time. As I was trying to say, it's the load that affects the output.

So I'm biting the bullet and getting the box changed. Very helpful and knowledgeable chap Simon at The Mechanical Workshop, Leicester. Not the cheapest or the nearest to me, but he seemed to know these gearboxes well. Let you know how I get on.

Can anyone confirm that later auto DSEs did indeed have an electric fan on the tranny cooler so that front fogs could be fitted? My coolers leaking anyway so whilst I'm at it I'll have new cooler and pipes and I'd have one with afan if possible for the fog lamp option. Part No?

revmarkp said:

So I'm biting the bullet and getting the box changed. Very helpful and knowledgeable chap Simon at The Mechanical Workshop, Leicester. Not the cheapest or the nearest to me, but he seemed to know these gearboxes well. Let you know how I get on.

Can anyone confirm that later auto DSEs did indeed have an electric fan on the tranny cooler so that front fogs could be fitted? My coolers leaking anyway so whilst I'm at it I'll have new cooler and pipes and I'd have one with afan if possible for the fog lamp option. Part No?

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The later DSE did indeed have a fan fitted to the cooler but it was NOT to allow fog lamps to be fitted, the cooling was marginal under certain conditions.
Fog lamps were NEVER fitted to the diesel.

Thanks Datatek.

Better forget those fog lights I think, I want to look after the new gearbox and I'm towing heavy.

Sounds like only the very last (not all 99MY on) vehicles had the fan. I can't find any info on it online though?? Anyone got any part numbers etc.

Any reason it might not fit on my older car? Are the four mounting lugs on this version of the cooler here where the electric fan mounts?

revmarkp said:

Thanks Datatek.

Better forget those fog lights I think, I want to look after the new gearbox and I'm towing heavy.

Sounds like only the very last (not all 99MY on) vehicles had the fan. I can't find any info on it online though?? Anyone got any part numbers etc.

Any reason it might not fit on my older car? Are the four mounting lugs on this version of the cooler here where the electric fan mounts?

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I'm sure you can fit the later cooler, not even sure it's different, wiring in the sensor and the fan is a different problem if you want it as per original.
You are right it was 99MY on.

Final update on this saga:

1. I suspect me spotting seized visous coupling due to this gear boax fault was nothing but conincidence.
2. I needed major overhaul on my gear box: I went to The Mechanical Workshop, Littlethorpe, Leicester. I can recommend Simon's work there. He's probably not the cheapest (although his default estimate for gearbox and TC replacement wasn't much more than Ashcrofts), it wasn't instant gratification (10 working days), he wasn't local to me in Worksop, BUT, he really new both auto gearboxes and Land Rovers.
Having heard a number of salutory stories about dirty ATF remaining in the cooler and pipes lousing up a new gearbox I had new of both of those as well. Rash I know but the cooler and one of the pipes were leaking anyway.

Two issues cropped up. The replacement cooler (Britpart) I bought didn't have the proper recess on it's side for the tranny temperature sensor.
Two fault codes cropped up: a TPS and engine temp, they both dissapeared when my 'hot fix' relay was unwired. I'm gonna post a new thread about that, as now (of course) it's not starting so well on warm/hot. Simon who wanted things right, wasn't happy about those fault codes, not least because the engine temp one also goes to the gearbox ecu and won't allow TC lockup until a certain temp.