AAZ (syncro) Aux coolant pump/switch

[steve770]

Hi folks, recently went out to find the new van had a flat battery which turned out to be due to the Aux afterrun pump permanently running after the engine is switched off.

The van came with an AAZ installed by a previous owner (from a JX) so not sure about how it's been set up. As I understand it there's two coolant sensors coming of the flange at the front of the engine - one for the temp gauge and the other for the glow plugs (these seem fine). There should then a coolant switch on the flange going into the cylinder head - this is what activates the afterrun pump (and should be switched at 104 deg). On mine I have what looks like the same sensor as the other two so three identical sensors - this one has two wires coming into it. Disconnected the wires and the the pump turns off (how I've left it just now).



I'm not totally sure what both wires are for - disconnecting the red one turns the pump off but any ideas what this brown/red one is for? I've read the syncro has a fan that should come on to cool the turbo at the same time as the afterun pump is that right? Would that be connected here?

I bought this switch (after reading issue was likely the switch) - https://brickwerks.co.uk/product/coolan ... ump-early/ but noticed the difference when I went to fit today.

Unsure how the current setup is supposed to work - eg when that pump should come on - could try replacing the sensor that's there with same one (or fit the switch I've bought and connect both wires to it).

Just trying to see if anyone has any ideas before messing about with it.

Thanks!
Steve
 

[Oldiebut goodie]

Sounds like someone fitted a sensor in error rather than a switch if you have 3 the same. Just test it with the new switch. ( I don't know what the 2nd wire is for though as my van had lost its JX setup before I got it)

[Aidan]

I think Andy has the wiring diagram on his website Syncrosport.com
IIRC both the aux water pump and the turbo manifold cooling fan should run on after turning off when hot so the block/head/manifolds cool down at similar rate, though it is rare for the system to still be in place or work, the cooling fan usually fails and the pipework gets butchered/lost during engine work
looking at the parts catalogue there seems to be choice of 1 pin and 2 pin temp senders for SyncroJX so there may be variants

[steve770]

Sounds like someone fitted a sensor in error rather than a switch if you have 3 the same. Just test it with the new switch. ( I don't know what the 2nd wire is for though as my van had lost its JX setup before I got it)

Yeh thanks - was thinking the same. Was just curios why it was only coming on now - bad sensor perhaps - forgot to actually test changing the wires to another sensor (since they're all the same). Anyway fitted the new switch yesterday which has of course fixed the issue eg no more pump running so should be fine. Guess I'm unlikely to hear this pump again over a Scottish winter!

I think Andy has the wiring diagram on his website Syncrosport.com
IIRC both the aux water pump and the turbo manifold cooling fan should run on after turning off when hot so the block/head/manifolds cool down at similar rate, though it is rare for the system to still be in place or work, the cooling fan usually fails and the pipework gets butchered/lost during engine work
looking at the parts catalogue there seems to be choice of 1 pin and 2 pin temp senders for SyncroJX so there may be variants

Perfect thanks. I can see the other wire is going behind the junction box in the engine bay and running to what looks like the turbo cooler - which as you say likely doesn't work - certainly wasn't coming on with the aux pump. Something to look into over winter