Defendern00b Posted February 11, 2022 Share Posted February 11, 2022 Can anyone tell me what ampage my alternator is from the pics alone? Came from a 91 200tdi. Standard 3 pin plug. Only identifiable part no's don't turn up any results on Google. They look like: BCH 06604 (stamped in centre) 21TR 37707A 0490 Cheers Quote Link to comment Share on other sites More sharing options...
nileseh Posted February 11, 2022 Share Posted February 11, 2022 Lucas A127. It's the same as the one on my '86 ex=MoD 110. Quote Link to comment Share on other sites More sharing options...
nileseh Posted February 11, 2022 Share Posted February 11, 2022 This is a picture of mine... 1 Quote Link to comment Share on other sites More sharing options...
nileseh Posted February 11, 2022 Share Posted February 11, 2022 Sorry for multiple responses, I think slowly in the morning. The parts manual for the '91 version of the ex-MoD 110 shows the alternator to be "A127/65". My guess is that it's a 65 amp alternator. The engine in the truck is the standard normally aspirated 2.5L diesel. Hope that helps. Quote Link to comment Share on other sites More sharing options...
simonb Posted February 11, 2022 Share Posted February 11, 2022 (edited) 4 hours ago, Defendern00b said: BCH 06604 (stamped in centre) 21TR 37707A 0490 BCH 06604 (stamped in centre) -Bearing type/number 21TR and 37707A Regulator part numbers 0490 - Regulator/alternator date stamp - wk 4 1990 Its a 45A machine, 65A variants have only bolt/stud connectors for the battery. 45A machines always have the spade connector/plug. Edited February 11, 2022 by simonb Quote Link to comment Share on other sites More sharing options...
Defendern00b Posted February 11, 2022 Author Share Posted February 11, 2022 Thanks for the responses here. I was thinking 45A because of the plug connector. Cheers Quote Link to comment Share on other sites More sharing options...
smallfry Posted February 11, 2022 Share Posted February 11, 2022 Just to add to what Simonb said 21TR is the regulator type 37707A is the Lucas part number It would have been sold as Lucas or Magnet Marelli Quote Link to comment Share on other sites More sharing options...
nileseh Posted February 13, 2022 Share Posted February 13, 2022 Not so much related to this, but you guys seem to know about these alternators. I'm trying to put a tach on my 2.5L diesel. I have a VDO 52mm device that is supposed to operate off the AC output of an alternator. That would be the "W" terminal, but I don't get an indication when I connect the tach. The alternator output at 750 RPM crankshaft speed is 1.2v at 650 Hz. Is that about right? Quote Link to comment Share on other sites More sharing options...
missingsid Posted February 13, 2022 Share Posted February 13, 2022 55 minutes ago, nileseh said: Not so much related to this, but you guys seem to know about these alternators. I'm trying to put a tach on my 2.5L diesel. I have a VDO 52mm device that is supposed to operate off the AC output of an alternator. That would be the "W" terminal, but I don't get an indication when I connect the tach. The alternator output at 750 RPM crankshaft speed is 1.2v at 650 Hz. Is that about right? I just looked on the Web and most answers came from boat owners. VDU tachos for connection in this format had a calibration system that needs to be set. Maybe a table of pulley sizes to look at or maths to be done as this decides the rpm of the alternator unlike ignition that is always tied to the engine. Quote Link to comment Share on other sites More sharing options...
nileseh Posted February 13, 2022 Share Posted February 13, 2022 Right, there are 3 on-off switches and a potentiometer to accommodate a range of frequencies. I tried all settings and potentiometer positions with no change. I think perhaps the device is defective, but I don't know what the alternator signal should look like to troubleshoot the matter. That said, the alternator seems to charge the battery adequately. Can anyone confirm the alternator waveform? Quote Link to comment Share on other sites More sharing options...
western Posted February 13, 2022 Share Posted February 13, 2022 On the VDO rev counter put slides 1 & 3 up & 2 down, there is a small screw on the side for fine tuning it, a 200tdi idle speed needs to be 750 to 850rpm, it has to be connected to the W terminal on alternator. Above is how mine is fitted to my 200tdi but with a 100amp alternator. Quote Link to comment Share on other sites More sharing options...
hurbie Posted February 13, 2022 Share Posted February 13, 2022 and i asume you need a good ground on the meter . Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted February 13, 2022 Share Posted February 13, 2022 Many years ago I used a VDO tachometer and had to create a W terminal, as there wasn't one present on the alternator. It wasn't a LR engine. The W terminal is connected to the output of one of the 3 coils, before that output reaches the diode pack. It doesn't matter which coil. The output is obviously alternating (AC), and as I suspect you realize, it is the frequency of the AC which matters. At the time I had no means of measuring the frequency, but I do recall measuring the voltage using the AC scale of a multimeter. I do not recall the reading, except it seemed rather low. You ask about the waveform; I'd assume sinusoidal, but I'm thinking you actually meant the frequency, the 650Hz you mentioned. The tachometer is actually going to measure the speed of the alternator, the switches and fine tuning are to cater for the different mechanical drive ratios (crankshaft pulley and alternator pulley sizes). To know whether your 650Hz is correct for an engine idle speed of say 1,000 rpm you need to know these sizes (diameters), and thus calculate the drive ratio. I did not have one at the time, but nowadays I have an optical tachometer which responds to a dash of white paint (or silver sticker) on the pulley. I have used this to measure crankshaft speed when setting the idle speed, but obviously the optical tachometer is not designed to be used whilst the vehicle is in motion! Not the exact answer, but the closest I could get 🙂 Regards. Quote Link to comment Share on other sites More sharing options...
nileseh Posted February 13, 2022 Share Posted February 13, 2022 Thanks for all the comments. I'll try again today with those settings. It's a sunny day in Oregon so I can get it out of the garage (wife dislikes the smelly diesel idling inside). Yes I meant inquire about the frequency and voltage, but it is sinusoidal, and I too have a optical tach to calibrate the VDO device. I don't think the drive ratio matters much insofar as the instrument can be set to accommodate any frequency. As long as the alternator speed remains constant relative to the crankshaft it should be okay. Quote Link to comment Share on other sites More sharing options...
Dunc101 Posted April 9, 2023 Share Posted April 9, 2023 (edited) On 2/11/2022 at 2:31 PM, nileseh said: This is a picture of mine... Hi nilesh - I also have been sent the exact same alternator for my Dakar 4x4 (kit based on the Range Rover Classic, 3.9 EFI), but I can't work out exactly what it is! Per your other comment above - is this an A127/65 alternator? Im looking for a replacement (upgrade) for an old Lucas A133-65 / 24155A / 478612v, and ive been sent this 'BCH 06604' unit. Ive no idea what it actually is. The mounting is [nearly] identical, but the lugs on the rear are different to the Lucas unit. If you can advise, was the A133-65 used on late Rover v8 3.5 CARB engines, or 3.9 EFI also? The engine on my Dakar is a mix of so many different parts from previous owners that I wouldn't at all be surprised if its the wrong alternator for a 3.9 EFI. Any info you can share / confirm on what this BCH unit is, and if at all possible - info regarding the correct / recommended alternator for a 3.9 EFI, will be greatly appreciated. Thankyou Edited April 9, 2023 by Dunc101 Quote Link to comment Share on other sites More sharing options...
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