T4 : Battle Across Time (2010 to present)

[Activ8]

Help needed.

While I had the coolant pipes off the bus over the weekend to reroute and make new ones up I thought I'd replace the coolant temp sensors for peace of mind etc...
The T4 is an AJT with AirCon and auxilliary pump.

Popped down to Euro Car Parts for the two sensors,
Got supplied a two pin sensor and a 4 pin sensor without thinking any more about it until I came to change them this afternoon.
Part number matched the top 2 pin sensor so in it went, but the the 4 pin was completely different.
I was supplied FEBI 059919501A but removed VAG 078919501C. Stuck the supplied unit in and hurried to the net to check.

The removed sensor is not recognised for the T4. OK - as everything has been working - hasn't it? - so what should it be...
So looked up the sensors online, but according to the ETKA image the green 4 pin supplied by ECP is a top sensor (part ID #7), see below;

TOP HOUSING SENSOR
(7) 025906041A temperature sensor, control unit, F >> 70-X-053 924 2 pin, blue, 20MM ;;1 AEU,ACV,AET,, AUF
(7) 251919501D temperature sensor, for vehicles with electro059919501A ni- cally regulated air condit., F >> 70-X-053 924 2 pin, green/black, 20MM ;;;1 AJA
(7) 074919501 temperature sensor, for coolant temperature gauge, F 70-X-053 925>> 4 pin, brown, 20MM ;;;1 AJA
(7) 6U0919501B temperature sensor, for vehicles with electric tachograph 20MM, green/black 1 AET,AEU,ACV,, AJT,APL,AUF,, AVT
(7) 059919501A double temperature sensor, F 70-X-053 925>> 4 pin, green, 20MM ;;1 AEU,AET,ACV,, AJT,AHY,APL,, AUF,AVT,AYC,, AXG,AYY
(7) 357919501 temperature sensor, for vehicles with electric tachograph 20MM, green/black 1 AJA
LOWER HOUSING SENSOR
(8) 701919369C temperature sensor with switch, for coolant temperature gauge, and/or, additional coolant pump, F >> 70-X-053 924 -- + 93/88C, 4 pin, blue/white, 20MM ;;;;;1
(8) 021919369 thermal switch, for vehicles with radiator fan run-on, and/or, additional coolant pump, F 70-X-053 925>> 93/88C 20MM, 2 pin, blue/white ;;;;;1 AET,AEU,AJA,, APL,AYC,AYY,, AXG,ACV
(8) 701919369D temperature sensor with switch, for coolant temperature gauge, and/or, for vehicles with radiator fan run-on -- + 100/95C, 4 pin, black/blue, 20MM 1 ACV,AUF,APL,, AVT
(8) 701919369E thermal switch, for deactivating the air- conditioning system, and/or, radiator fan 105/112C 20MM, 106/102C, 4 pin, green, 3 stages 1

Can anybody shed some light on the correct sensor required for the AJT with A/C, with temp gauge, auxilliary pump and radiator fan run-on?

[Activ8]

Just pulled two sensors from other vans with A/C but both are ACV engine codes - part numbers removed .... you guessed it VAG 078919501C (the one not recognised for the T4!) All the sensors removed have been black with no additional colour coding.

[Activ8]

Just plugged in VCDS with ignition off after unplugging both sensors to show a forced error. Replugged them in and cleared the recognised errors. So the ECP supplied sensor "works".

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[frenchdna]

Not that I really understand any of this, but even so, it somehow captures my attention, so that I even find myself looking up part numbers for sensors!!!
Not that I need any sensors as I haven't even got an ECU. Lol

[Activ8]

Noticed a tiny water leak last night from the upper near side service position lever arm mount. From a hairline crack coolant was seeping out in the service position from lifting out the radiators into service mode. No visible leak in the drive position but as the system becomes pressurised (upto 1.5bar) it will leak. [emoji17].
Here's the part numbers and alternatives for these short nose T4 models:
VW Transporter Caravelle MK IV Bus 1.9 TD (1990 - 2003) 50kW
VW Transporter Mk IV Box 1.9 TD (1990 - 2003) 50kW
VW Transporter Mk IV Box 2.5 TDI (1990 - 2003) 65kW
VW Transporter Mk IV Box 2.5 TDI (1990 - 2003) 75kW
VW Transporter Caravelle MK IV Bus 2.5 TDI (1990 - 2003) 75kW
VW Transporter Mk IV Box 2.4 D (1990 - 2003) 57kW
VW Transporter Caravelle MK IV Bus 2.4 D (1990 - 2003) 55kW
VW Transporter Caravelle MK IV Bus 2.4 D (1990 - 2003) 57kW
VW Transporter Mk IV Platform/Chassis 2.5 TDI (1990 - 2003) 75kW
VW Transporter Mk IV Box 2.4 D (1990 - 2003) 55kW

Equivalent Part Numbers:
VW 701.121.253 M; VW 701.121.253 E; VW 701.121.253 D; VW 701.121.253 F; VW 701.121.253 K; NRF 509514; FRIGAIR 02103003; NRF 232397; NRF 1007; GERI 16267; AKG 47870090000; QUINTON HAZELL QER1421; QUINTON HAZELL QER2363; GERI 16261; VAN WEZEL 58002114; VALEO 732397; VALEO 732845; VALEO 232397; BEHR HELLA SERVICE 376714481; BEHR HELLA SERVICE 8MK376700481; BEHR HELLA SERVICE 8MK376714481; AVA QUALITY COOLING VWA2114; ARD 311199; ARD VOLK5365; AVA QUALITY COOLING VW2114; AVA QUALITY COOLING VW2114A; JDEUS 030B34; SCHLIECKMANN 60582114; AKS DASIS 1300131; AKS DASIS 3500501; AKS DASIS 240050N

System Requirements:
Core Dimensions(mm): 718-359-32 10MC
for OE number: 701.121.253 K

Found a new Nissens unit for £45 after working through the above alternative part numbers.



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[Activ8]

I've been looking at the coolant thermostats and thought this might be useful info with the ambient temps being so high at the moment.

Thermostat
Starts to open at 87°C.
Fully open at 102°C

Electric Fans
Cooling Fans Cut In
Stage1 speed - On @ 84-89°C Off @ 76°-83°C
Stage2 speed - On @ 90-95°C Off @ 82-89°C




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[lister]

There is a company on ebay making aluminium radiators for t4s now. Dont know if you would require additional cooling with all the upgrades you are doing

[Activ8]

There is a company on ebay making aluminium radiators for t4s now. Dont know if you would require additional cooling with all the upgrades you are doing

Cheers - appreciate that. I've got a lot of data now on the temps so I'll compare as the mods get added. Coolant cooling on the T4 is very good holding the temps whilst hard driving at around 82°C but in traffic / at lights the temps rise quickly but the fans tend to work efficiently. Thought about modding the fan stage temps in the ECU to aid the top mounted intercooler (interwarmer[emoji6]Reg) but let's wait and see.

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[lister]

You can get different fan switches. If you look on the vw heritage website they do a fan switch that kicks in earlier. Its designed for hot countries, vehicles that tow.

[Activ8]

You can get different fan switches. If you look on the vw heritage website they do a fan switch that kicks in earlier. Its designed for hot countries, vehicles that tow.

Cheers , yes been looking last night at those and in light of my earlier postings regarding the sensors.

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[Activ8]

Something I picked up as useful info from the VW HERITAGE site is the part number for the 4 pin coolant sensor plug.

PN#4B0973712 - block connector for coolant sensor. About £3 with tails on eBay. Mine were difficult to disconnect and brittle but intact, you could easily break the clip off.


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[lister]

https://www.vwheritage.com/701959481...7-76c-vw-spare

[Activ8]

https://www.vwheritage.com/701959481...7-76c-vw-spare

Thanks. I picked a couple of Valeo units up last night on Amazon for £2.50 each... £13 with VWH thinking they could be useful. Great minds and all that!

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[Activ8]

Assumed the flange mounting to airbox was flat - does it have a cylindrical section that you just clamp the hose on to?

This might help Reg from the Apollo box...



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[Activ8]

- just waiting for some flange drawings from a bloke who has all the turbos.

Email sent, its Razzle for Engineers who like the dimensions drawn on or near their flanges!