Temp Sender on Turbo Water feed

[chrisg]

Morning All !

For the more technically minded or experienced, what exactly does the temperature sender that sits in the water feed (banjo joint) to the turbo do ? This sits on the LHS of the turbo - you can just see it under the inlet manifold very close to the throttle body and it has a single yellow wire going into it.

I've looked on the Electrical diagram and it just feeds into the DME.

The reason I ask is mine looks suspiciously knackered = sender is wobbly and not secure but no water leak.

I've ordered a new one from OPC, but I'm reluctant to start fitting it in advance of the Ring trip in July - looks very difficult access and really best to do once Inlet manifold is removed.

So, what exactly does it do and what are the potential consequences of it not functioning properly ?

thanks in advance,

Chris

 

[TTM]

It starts up the turbo cooling pump when coolant temp in the pipe reaches 115°C.

Given that the fans should run on high speed when the temp switch on the rad reaches 102°C, the question now could be how high coolant temp actually gets in the area of the turbo...

I have been wondering about this since I can monitor coolant temp with my new ECU, and as the figures I see make me wince I think I should invest in a laser temp gun...

 

[chrisg]

Good man thanks for the advice- much appreciated !

 

[GPF]

Surely, the point is that it is used to contol the turbo electric water pump that is only active when the engine is shut down and the main water pump is therefore not running?

I have a non standard sensor in mine that lowers the temp at which the pump is activated.

 

[TTM]

Well, even when the sensor is removed the DME will switch on the pump when the engine is shut down, so I think its main point is to cool down the turbo center housing when it gets really hot as the engine is still running - I don't have this sensor on my set up yet the pump is still switched on when the engine is shut down.

However, I'd be interested to know under which conditions it would get as hot as 115°C, as if the fans will always kick in at high speed when coolant at the entry of the rad reaches 102°C, then what could well be coolant temp in the turbo center housing??

It would be interesting to establish a coolant temp map of the cooling system, where the various peaks/lows are.

Edited to add : do you chaps think a faulty fan temp switch could cause the fans to run in high speed higher than normally?

 

[Diver944]

I believe Tony F tested this a while back by fitting an LED in the cabin connected to the sensor.

Sure enough, under high load this sensor switches on the turbo coolant pump when the car is running

 

[944Turbo]

Yes I had to wait until the coolant was almost hot enough to trigger the fans then some heavy acceleration in 3rd + 4th would trigger it. that was on a warm 20ish degree day