Taco Readings high - 300Tdi

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Originally Posted by **Discovery300Tdi**

Now i seem to recall everything was all good and dandy after the trip to talla. so i take it it must have been when he put the new alt in. might have to splice all the wiring behind the alt and start off fresh and see what happens. OR the auto is about to go boom which wouldnt surprise me lol. if it does might have to cut a hole in the floor on the drivers side and go flintstone style for a while lolol

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OR don't touch a thing, take it back to him and get it done right.
If it only played up since the new-new-new one went one thats where the problem lies;)

You just have no luck with the Disco do you?

There is one usually white wire that goes to back of alt. If loose you may get fluctuating readings.
I did after new batteries fitted and had to put new connector on myself.

When you rev to 4k, does it still perform, I rarely go past 3000rpm, and find much higher and it does not really pull much, may-be your rebuild has done you some good and she really wants to rev?

Either way mate, hope you get her sorted, soon it be best Disco on here.

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Originally Posted by big guy

You just have no luck with the Disco do you?

There is one usually white wire that goes to back of alt. If loose you may get fluctuating readings.
I did after new batteries fitted and had to put new connector on myself.

When you rev to 4k, does it still perform, I rarely go past 3000rpm, and find much higher and it does not really pull much, may-be your rebuild has done you some good and she really wants to rev?

Either way mate, hope you get her sorted, soon it be best Disco on here.

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Thanks mate. Here i was thinking that when you get a new engine all is well..BOY WAS I WRONG!!!!!!! LOL

when it rev's high say past 3500k yeah she still pulls, actually the higher revs the harder she goes mind you i have had the injector pump tweaked and got it boosted to 16psi. but power wise i have no problem what so ever it just feels alittle weird seeing it rev that high on the tacho..thought it might be my auto packing it in but not sure.

On my 300tdi the wire that controls the Tacho meter is the yellow one closest to the passenger front wheel.. Mine was "loose" and giving me all sorts of funny readings.. Make sure it is a tight fit otherwise who knows what it is really reading... I also wonder if the voltage output for the tacho would be different on a 100Amp alt from a def.. Seeing as how these do not run a tacho stock, I wonder how it has been rigged up??

Does your new alternator have the same size pulley as your old one?

The rate at which the alternator spins is what the tacho is reading so if there has been any change in the pulley size it will alter the calibration of the tacho.

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Originally Posted by slug_burner

Does your new alternator have the same size pulley as your old one?

The rate at which the alternator spins is what the tacho is reading so if there has been any change in the pulley size it will alter the calibration of the tacho.

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yes this would also give funny readings.. A smaller pulley could be the reason .. This would seem to make the most sense with regards to reading high. A larger pulley would read slower.

Ill take a few pics today and post them up. From what I can gather the alt o have on now is a 100Amp from a disco which before I had one from a defer which was 65amp. When I had the 65amp hooked up they i
put a small 6 ribbed pulley for a 7 ribbed belt, tacho was fine then only prob was he'll of a lot of sqealing, changed the pulley to a bigger and 7 ribbed one and all was fine. This pulley now seems right.