Temp sender unit on 300TDI with a TD5 instrument panel

[Pastycrimper]

OK Good Folks,

The rebuild is finished - And yes I will post an essay of the whole massive story (personal and mechanical)  into rebuild/owners vehicles section. I'm back to work at sea on Monday so not sure quite when I'll have it done but it's coming I promise!.

BUT in the meantime. It was a 1997 300TDI. It still is really but many of the new parts came from later vehicles including a a good condition instrument panel from a 2006 TD5. I have the 1997MY elec diagrams and also the 2002MY elec diagrams. They clearly used an engine control module (ECM/ECU) on TD5s which I don't have. The diagram in MY2002 clearly shows alternatives for TD5 and 300TDI (I assume this is because 300TDIs were still shipped to the international market even after 1997).

Anyway as far as I can see, for a 300TDI you just wire it as per the normal 300TDI diagram - i.e. temp sensor direct to coolant temp instrument gauge however I have tried this and the gauge only raises to middle of blue section when at full running temp. So either they made different temp sensors (which I guess had different resistances and hence voltage ranges and thus effect how much the needle moves on the gauge) or I have made a mistake elsewhere.

Anyone else basically got a 300TDI MY but installed a later TD5 instrument panel? Any ideas?

[Pastycrimper]

Crikey - I spend all day researching this topic, give up, post on here and then 5 minutes later maybe I found the answer.

I can find two separate temp sensors for a 300TDI:

1. AMR1425 - Which has a green collar
2. AMR3321 - Which has a black collar

They both look identical apart from the collar colour - I am assuming I have the wrong one! Does anyone know the difference between these two senders? Think I'll just buy the other one and try and see

[Retroanaconda]

You need the green sender. You also need to modify the wiring in the instrument harness to mimic the rest-of-world spec vehicles. The wire from the sender goes into the speedo head and then out to the gauge.

[Mo Murphy]

... it goes through a resistor on the speedos circut board which modifies output to the temp gauge. 

Mo

[oneandtwo]

And don’t be alarmed when it’s all done with the time it takes for the engine to warm up on the instruments. Mine with original instruments used to be up to temp after a minute or two. Soon as I swapped to the late sender and td5 instruments warm up period took 4 times as long.

[Pastycrimper]

I'm Looking at the 2002MY diagrams. For a TD5, the sender unit (sensor) has two connectors which go straight to the ECM and then one wire to goes from ECM to speedo and then to the guage. However for TDI variant, in the same diagrams it says connect the sender direct to the gauge. I've attached screenshots of these which I have very terribly tried to annotate in red showing the TDI wiring not the TD5.

4 hours ago, Retroanaconda said:

You need the green sender. You also need to modify the wiring in the instrument harness to mimic the rest-of-world spec vehicles. The wire from the sender goes into the speedo head and then out to the gauge.

So I think "rest-of-world wiring" is to bypass the speedo and go straight from sender to guage

4 hours ago, Mo Murphy said:

... it goes through a resistor on the speedos circut board which modifies output to the temp gauge. 

Mo

Especially if there is a resistor in the speedo and God knows what voltage changes happen in the ECM for TD5. 

[Pastycrimper]

Alternatively has anyone found a third party more accurate temp sensor that screw into the same thread and sends to an external dial accurate temperatures?

[western]

I had my green top sender wired direct to the gauge, missing out the Speedo 

the LR one will screw straight in to any 300tdi.

 

or change the LR parts to VDO gauge & matched sender.

 

[Pastycrimper]

39 minutes ago, western said:

I had my green top sender wired direct to the gauge, missing out the Speedo 

the LR one will screw straight in to any 300tdi.

 

or change the LR parts to VDO gauge & matched sender.

 

VDO - that was the name I was trying to remember! In the offshore world I use PRT (platinum resistance thermometer) for seawater temperature and these are very accurate (O.1 deg) (PRT)  - Not sure what technology VDO use but was wondering if there are PRT sensors and matching guage. It would be nice to know exactly what temp the coolant is

[Ex Member]

The sender is 1/8" NPT.  Very common.  The TD5 gauges and senders are actually made by VDO.

Anyway, get a VDO Vision Gauge in 52 mm and a 1/8" NPT sender to match it and you can read real numbers.

[landroversforever]

The info for wiring it all up is on James' website retroanaconda.com That's how ralph ( @western) and I wired mine in and it worked faultlessly.

 

EDIT: 

Here: http://www.retroanaconda.com/landrover/2009/10/installing-defender-td5-gauges-into-a-200tdi300tdi/ 

[dailysleaze]

This is the thread you want that explains all

 

[Pastycrimper]

7 hours ago, landroversforever said:

The info for wiring it all up is on James' website retroanaconda.com That's how ralph ( @western) and I wired mine in and it worked faultlessly.

 

EDIT: 

Here: http://www.retroanaconda.com/landrover/2009/10/installing-defender-td5-gauges-into-a-200tdi300tdi/ 

Well I couldn't ask for more than that! And then delving into the thread @dailysleaze linked above satisfied all of my curiosity especially the picture of the circuitry in the speedo which I suspected was more than just a resistor or two. I'll get the green collar in tomorrow as I think the wiring is currently as Retroanaconda's diagram now.

Although I am now distracted by third party senders and gauges namely this sender (https://www.auberins.com/index.php?main_page=product_info&cPath=20_15&products_id=134) with this gauge (https://www.auberins.com/index.php?main_page=product_info&cPath=5_21&products_id=504).

Side question - what should be the normal running temp of a 300TDI under normal conditions? And what temperature is considered the start of bad things happening for a 300tdi - If the needle is in the red what temp does that indicate? Prior to rebuild (and aside from a rad issue I had once) I think as fro most people my gauge always sat just fractionally below half way. Only once towing a heavy trailer up  what us Cornish call Pig Sh*t Hill on the A30 did the gauge run up to about 2/3rds. What temp is that and would a 300tdi keep running happily at this temp?

Anyway I'm pretty skittish about engine temps and I'd prefer to know the numerical value rather than a needle.

Edited May 26, 2018 by Pastycrimper
bad spelling

[western]

All Tdi engines standard factory temp sender is 88 degree,  mine usually runs around 88 to 95 in normal driving rises a bit if climbing hills but drops back to 90 on level roads, I had100 on it yeasterday when pulling up a long hill but it dropped back, 

these are my sender & gauge are VDO units,  gauge reads upto 120 degrees. [as an example] theymatch the Td5 gauges quite well as VDO actually made the Td5 gauges for LR [they have VDO labels on the gauge bodies]

https://www.merlinmotorsport.co.uk/p/vdo-water-temperature-gauge-310010002

https://www.merlinmotorsport.co.uk/p/vdo-water-temperature-sender-5-8-unf-thread-323801001008

my temp gauge can be seen in a photo on page 5 about halfway down the page of my engine rebuild post -- https://forums.lr4x4.com/topic/101989-my-24-year-old-200tdi-rebuild/?page=5

 

[Pastycrimper]

14 hours ago, western said:

All Tdi engines standard factory temp sender is 88 degree,  mine usually runs around 88 to 95 in normal driving rises a bit if climbing hills but drops back to 90 on level roads, I had100 on it yeasterday when pulling up a long hill but it dropped back, 

these are my sender & gauge are VDO units,  gauge reads upto 120 degrees. [as an example] theymatch the Td5 gauges quite well as VDO actually made the Td5 gauges for LR [they have VDO labels on the gauge bodies]

https://www.merlinmotorsport.co.uk/p/vdo-water-temperature-gauge-310010002

https://www.merlinmotorsport.co.uk/p/vdo-water-temperature-sender-5-8-unf-thread-323801001008

my temp gauge can be seen in a photo on page 5 about halfway down the page of my engine rebuild post -- https://forums.lr4x4.com/topic/101989-my-24-year-old-200tdi-rebuild/?page=5

 

Nice gauges Ralph! I, like you, like to know what is going on. Interesting in your thread above on your journey to Swindon and back you said the temp was sat at 85 degrees. This now intrigues me about the thermostat which I assume only opens at 88 degrees, or does it start partially opening before 88 degrees? I guess you can sense where I am going here.........was your thermostat always closed (not very likely) or is it that 200/300tdi's seem so good at holding running temperature that on a long drive (without heavy loads or silly hills) the thermostat is opening and closing quite frequently? My assumption is that at running temp at idle the thermostat would be open.........time to get a heat proof, water proof mini endoscopic camera with LED drilled onto the the thermostat housing and a small screen on the dash so I can watch live video of my thermostat while driving!

[western]

fitted a new stat when the new temp sender & gauge was fitted, it opens around 88 so could be starting to open around 85 will take a bit more notice on the drive home monday afternoon. 

[Pastycrimper]

6 minutes ago, western said:

fitted a new stat when the new temp sender & gauge was fitted, it opens around 88 so could be starting to open around 85 will take a bit more notice on the drive home monday afternoon. 

I'm just being unnecessarily nerdy! Given stats are bimetallic mechanically actuated I suspect they have a small range over which they open...as in it is not just fully open/fully closed at half a degree either side off 88.

Either way I may get the PRT sender and guage. As mentioned above we use them on the HPUs of our subsea machinery as we have to really closely monitor subsea hydraulic equipment temps. They're very accurate and relatively cheap.

[Ex Member]

19 hours ago, Pastycrimper said:

I'm just being unnecessarily nerdy! Given stats are bimetallic mechanically actuated I suspect they have a small range over which they open...as in it is not just fully open/fully closed at half a degree either side off 88.

Thermostats do not use bi-metallic strips.  They use wax.  When the wax melts, the thermostat opens.  The melting temperature is very specific and it opens quickly at that temperature.  The temperature rating is the temperature that the wax melts.  With a proper gauge, you can see it open.

[Pastycrimper]

2 hours ago, Red90 said:

Thermostats do not use bi-metallic strips.  They use wax.  When the wax melts, the thermostat opens.  The melting temperature is very specific and it opens quickly at that temperature.  The temperature rating is the temperature that the wax melts.  With a proper gauge, you can see it open.

Thanks Red90. How wrong I was!

When you say specific temperature, how specific? My knowledge of wax is as it starts to melt there is a  range over which is goes from viscous to less viscous - it's this range  I am interested in - as in it doesn't go instantly from full solid to liquid at precisely 88 degrees. Me and my Dad years ago gathered a collection of stats from his shed and out of a S2A and S3 and my 300tdi and warmed them slowly in a pan to try and establish which of his spares was which, and yes they did open at different temps, however visually it looked like the opening was over a range of 1 to 3 degrees  rather than say a 0.5 degree range.

[Ex Member]

There is a place called the internet, from which you can research any subject of interest, all on your own.

[western]

11 hours ago, Pastycrimper said:

Thanks Red90. How wrong I was!

When you say specific temperature, how specific? My knowledge of wax is as it starts to melt there is a  range over which is goes from viscous to less viscous - it's this range  I am interested in - as in it doesn't go instantly from full solid to liquid at precisely 88 degrees. Me and my Dad years ago gathered a collection of stats from his shed and out of a S2A and S3 and my 300tdi and warmed them slowly in a pan to try and establish which of his spares was which, and yes they did open at different temps, however visually it looked like the opening was over a range of 1 to 3 degrees  rather than say a 0.5 degree range.

a couple of links 

https://en.wikipedia.org/wiki/Wax_thermostatic_element

https://www.youtube.com/watch?v=f45kAmjAOYA