KV6 coolant temp sensor location
 

I am sorting a cooling issue on a V6 that I have recently got. Just spoke to the previous owner and the coolant temperature sensor was replaced. When I have looked they have plugged it in next to the coolant pipes on the engine block but not connected the other side.....

I cant quite see where it plugs in does anyone have a diagram or know where it goes. I have removed enough to get it but don't want to remove the manifold just to plug it in

This is the sensor I mean https://www.dmgrs.co.uk/products/oem...45-75-zr-zs-zt it is plugged into the sensor but not they did not connect the harness.

Does the fan run when you start the engine? If the sensor isn't sending a signal to the ECU, it will trip on the emergency cooling program.

The sensor is located on top of the engine, near the thermostat housing (between the 'V').

What do you mean by 'plugged in' next to the pipes, but 'not connected' the other side'? Is there not a wiring harness plugged into the end of the sensor?

Thanks. It is connected to the sensor i.e in the V next to the thermostat but I assume when changed they forgot to connect the other end of the harness


As this picture in post 2 https://the75andztclub.co.uk/forum/s...ad.php?t=37359 it is plugged in as here but the other end of the harness is not connected.

Does the radiator fan start when you start the engine?
Does the temperature gauge stay in its ignition-off position?

TC

No & No

All function ok other than pressure in the tank so coolant is not cycling around I have I just need to see where it plugs in as I they have changed the sensor but not plugged it in.... I cannot see a photo or haynes where the harness connects

Dominic,

I understand what you're asking and you're right, the wiring from the sensor connector is short and terminates just to the rear of the right-hand bank where there is another connector buried underneath the plastic inlet manifold chamber.

However, in reply to T-Cut's question you said that the temperature gauge does not remain in the full cold position when the engine is warm. Have I understood that correctly? If the gauge needle is rising towards the mid-position as the engine warms then the sensor must be connected. :shrug:
Pressure in the tank? Did you remove the expansion tank cap when the engine was stone cold? Did you hear a strong hissing sound?
Why do you believe that the coolant isn't "cycling around"? It will circulate provided that the water pump impeller hasn't dropped off its shaft! ;)

Simon

It's not possible to verify coolant circulation other than by the way it controls the running temperature. There's no circulation through the header tank, so an apparent lack of flow there is meaningless I'm afraid.

From what you've said, the temperature gauge seems to be working and will provide important clues. Does the gauge sit at 'normal' (9 o'clock position) when driving? If so, the coolant is circulating. This fact is unequivocal. If there were no circulation, the gauge would hit the red line in a few minutes.

Pressurisation of the header when the engine's running is a natural consequence of the sealed coolant system getting hotter. The hotter it gets, the higher the internal pressure. The system runs quite normally up to 22psi or so using a '140' pressure cap. It's designed to do that and the cap shouldn't be touched other than for checking the fluid level when the engine is completely cold.

I honestly think your concern about the sensor harness is unfounded, unless there's another temperature related issue you've not mentioned.

TC

Apologies for the late reply and the hurried one now. I have uploaded a few photos of the connector I mean I will have a good look over the weekend and report back. Here is a link to the photo. I just assumed it must be plugged into something.

Maybe they have wired it differently. What led me to believe there is an issue is that I was sure that when the car was running coolant would come out the little hole top left of the tank and recirculate, is that not the case.

https://goo.gl/photos/kb36iZZkfQ4ty39Y8.

The small hole you mention is of no significance in terms of coolant circulation. It's usually watched when the system is being refilled and bled. The small hose connected to the header tank neck connects to this 'bleed' hole and vents air from the heads as they fill. However, there's a much larger hole also leading from the bleed hose that's out of sight under the neck. During normal operation, the smaller hole is sealed off by the pressure cap o-rings. It may also be possible to observe a tiny flow from the other hole when the engine's running (and the cap off of course), but it's of no significance. It may even stop completely when the tank's sealed and pressurised. The header contents are basically a stagnant reserve of coolant that doesn't reach the same temperature as the engine coolant. For more details see: https://the75andztclub.co.uk/forum/s...d.php?t=245285

I'm unfamiliar with the V6 so can't comment on the plug in the photo.

Can you confirm that the temperature gauge points at 'normal' when driving?

What circumstances did you notice pressure in the header tank?

TC

i know this is an old post but this one plug next to the throttle body you have in the pic is not for the coolant temp sensor. did you ever find out?