2.5 TD in a Series 3

drewjones · Dec 14, 2007

I've inherited a 2.5 TD (19J) engine in a Series 3. The Temp Gauge and the Oil Pressure lights don't work. I've check the Oil light circuit and shorted the return to the switch to earth and the lamp lights. SO i would assume the switch is faulty,

but

A its a 2.5TD switch, or variable resistor on the engine (assume the same for the Temp Sender) are they compatible or do in need a form of conversion ?

Thanks in advance !

Sean · Dec 14, 2007

the only proper way to do this is to fit a TD temp guage in one of those dash mounted pods as the guage needs to match the sender - it'd certainly not be impossible to get the series guage reading but, as you mentioned, there would have to be some messing doing first - that's a good question and as i have a series dash in the garage i might go experiment as a few people have asked if i'd put a TD in a series

the oil warning light should work without any issues

have you ever seen the temp guage move ?

drewjones · Dec 14, 2007

I've never seen it move before, i have a spare one it think, that i know works (or did when i took it out)

The Mad Hat Man · Dec 14, 2007

I am at a bit of a loss to understand this common problem on landies....

1) the oil pressure switch is exactly that - a switch - it is designed to close at a pre-determined pressure - 5PSI? - and then grounds the input wire. It shouldnt matter what switch yu use, providing it fits the engine.

2) the Temp gauge is just a Voltmeter - I think, designed to read FSD (Full Scale Deflection at 10.5 volts (the output from the voltage regulator). The correct sensor is a Thermistor (variable resistor), mounted in the cooling system. if yu are getting the correctly regulated voltage on one side of the Gauge, no high resistances in the wiring - It is such a simple system - why peeps seem to have continuous inaccurate gauges is beyond me.

Can some on explain why, what should be simple electrics, always seem to cause problems?

CharlesY · Dec 14, 2007

To get the TEMP gauge working right you will have to use the proper SENDER unit from the engine that was originally in the car.

The sender and gauge must MATCH or the gauge reads all to Hell and back again.

You may need to fit the correct sender into the head near the back top left corner.

CharlesY

The Mad Hat Man · Dec 14, 2007

that still dont explain why that shud be - it dont make sense!

slob · Dec 14, 2007

maybe the sender work over a different range of resistance therefore letting a current outside the gauges range go through the gauge.or vicky verky

Sean · Dec 14, 2007

slob said:
maybe the sender work over a different range of resistance therefore letting a current outside the gauges range go through the gauge.or vicky verky

exactly, it's possible to get the almost any guage to read correctly at any single temp using almost any temp sender using a couple of resistors (the value could be caulculated but trial and error would be much quicker) but you'd end up with inaccurate indications at any temp other than that

2.5 TD in a Series 3

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