BX XUD9A tacho query

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white exec
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BX XUD9A tacho query

Post by white exec »

The sensor that drives the tacho has gone open-circuit on the '92 BX19D.
VIN: VF7**************[VIN obfuscated, can be read by forum staff]

Having difficulty in identifying exactly which of the listed sensors is the correct one for 1905 diesel tacho drive, rather than 1905 petrol timing etc.

The parts page makes it look like 5918.75 (#2) is the right one (and looks the right shape), but is this correct?
Sensors.JPG
The other question was about tacho triggering...
Is the sensor looking for spigots or notches on the flywheel perimeter?
How many pulses are seen per flywheel rev? I think it might be two, but unsure.

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Re: BX XUD9A tacho query

Post by xantia_v6 »

Looking at the Peugeot 205 parts list, 5918.75 seems to be correct for the 205 with XUD9.

Does this look like the same part? https://www.ebay.co.uk/itm/BOSCH-0-986- ... 3993378077

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Re: BX XUD9A tacho query

Post by white exec »

That looks right, Mike. Thanks.
Not at all helpful that Cit Parts, under a correct diesel VIN, list what could be/are petrol (1905L and 16S) parts! #-o

What's the preferred method of setting the sensor position (closeness to the flywheel) in the clamp bracket?
Access to it, engine in situ, is pretty grim.

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Re: BX XUD9A tacho query

Post by Pug_XUD_KeenAmateur »

Surprised you're struggling for access Chris; coz while I'm not familiar with the BX Engine Bay surely its broadly the same as my 405 Bay with the same XUD9A, with perhaps some extra suspension gubbins.

I access it from the top, having removed Battery, Air Box and Trunking.

I've never been fussy about 'Distance from the Flywheel', just push it 'Home' then pull it back a couple of mm.

Tacho issues are usually the Sensor, but in my case it was the Tacho itself. I do have spares I can photograph if you want a 'reference', though I can't be sure if they're the same....

...saying that, most of my spare Tacho Sensors have come off scrappers / spare engines from various Models and Years and I've never found any discrepancy between any of 'em, including when testing / fitting so think a strong chance they're all the same.

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Re: BX XUD9A tacho query

Post by white exec »

An FAE 79156 (= 5918.75) ordered from Mister Auto.

Thanks, Puxa. Will take another look. Swinging the HPP pump away helps with access.
Am I right in thinking that the sensor is looking at the smooth edge of the flywheel (next to the starter teeth), and has ?2 notches machined into it, 180º apart?

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Re: BX XUD9A tacho query

Post by white exec »

Just found this, in Haynes - tucked away in Engine and transmission - reconnection :
Refit the TDC sensor and holder and tighten the bolts. When the TDC sensor is fitted new it incorporates three legs which are 1.0 mm (0.040 in) long and these automatically set the sensor 1.0 mm from the flywheel/driveplate. When fitting an old sensor the legs should be filed off – the unit can then be fully inserted until it touches the flywheel/driveplate and then withdrawn by 1.0 mm (0.040 in) before tightening the bolts.
Citroen Diesel Engine, 1990 p.76 §28.9
pic from the web
pic from the web

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Re: BX XUD9A tacho query

Post by Pug_XUD_KeenAmateur »

I’m guessing that’s a Cam Driven HPP Pump on the Gearbox side, in the same way as my 1987 309 GRD had the early style Cam Driven PAS Pump

I haven’t looked at my Tacho Sensors in a while, but while I’m not completely sure, I don’t think there’s any notches in ‘em, one of which is new; I can put my hands on em readily, so happy to have a Butchers if you like

Never given any thought to the location, but looking at my photos, attached in case they’re useful; looks like you’re right

Be curious to see the BX bay with Spheres, HPP Pump ‘n’ all that, see how different it is. Guessing it might be old enough to be the ‘early’ layout coz would imagine the HPP pump got ‘moved’ to being Aux Belt driven instead of Cam Driven, in a similar way to how the PAS Pump did on the 405’s
Chris 1.jpg
Chris 2.jpg
Chris 3.jpg