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Author Topic: small coolant leak and fans on constantly when ignition turned on  (Read 868 times)

Offline cravenbiker

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  • Model: Alhambra Mk1
  • Spec: 1999 1.9tdi 81kw
  • First Name: Tristan
  • Region: Non UK
hi. not sure if this is a complete coincidence but i doubt it. after the school run this morning. get home, get ready go go back out after an hour and noticed rad fans kicked in as soon as i turned the ignition on.
got out to check under bonnet and found a pool of coolant by my feet. reservoir still full up to the top of the outlet hole. pulled the connector off the rad sensor but this made no difference.
found the leak coming somewhere just to the left of the oil filter (if you are looking into the engine bay from the front of the car). think its thermostat housing. any ideas of why the fan will not turn off or how to test the system?

Thank you


T

Offline brianh

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  • Model: Galaxy Mk2
  • Spec: 2001 2.3 Ghia LPG
  • First Name: Brian
  • Region: South East
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Re: small coolant leak and fans on constantly when ignition turned on
« Reply #1 on: January 17, 2019, 07:24:18 PM »
It has been the case for others if you have the external temp sensor, and its not displaying the right temp (very high) that it will run the fans constantly, I don't know if that applies to the mk1 though, mine never had a display for the temp, but that doesn't mean yours doesn't.

Thermostat housing may have just failed - they can and do crack after a while.

The expansion bottle has a level sensor on it, but it may not work (Both my mk1 and mk2 ones have stopped working), theres a lot of liquid in the system of these, so you may have lost some from the heater system due to the leaky housing but still have quite a bit in the system. Theres also a gasket inside the housing, it may be that this has gone hard and not sealing well enough anymore, until you remove it or can see exactly where its leaking from, you can't tell which bit you need (if you can pressurise the system then you stand a reasonable chance of seeing the exact locaction of the leak, as you can then do it with cold fluid in there so you can feel for the leak much more accurately)

I don't know how the fans on the diesel are controlled, but its possible the sensors on the thermostat housing have something to do with it The petrols have 2 sensors, one tells the ecu how hot the coolant is, the other one drives the gauge. I don't know if the diesels have anything similar going on, but with the petrols you can look at the obd data to see what the other sensor is seeing, if its showing something daft it may be the sensor has failed in some way, if your really lucky that may be your leak. Go careful when your putting the sensor back into the housing, its easy to over tighten them and break the housing by doing so.
« Last Edit: January 17, 2019, 07:27:47 PM by brianh »

Offline cravenbiker

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  • Model: Alhambra Mk1
  • Spec: 1999 1.9tdi 81kw
  • First Name: Tristan
  • Region: Non UK
Re: small coolant leak and fans on constantly when ignition turned on
« Reply #2 on: January 17, 2019, 09:22:45 PM »
It has been the case for others if you have the external temp sensor

Im guessing the sensor for this is the sensor that i have found and moved about recently while replacing the turbo which is found close to the control unit screwed above the radiator?


Thanks for your input. I will go through each of your suggestions tomorrow morning to help narrow down the issue. starting with the external temp sensor.

thanks again

Offline brianh

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Re: small coolant leak and fans on constantly when ignition turned on
« Reply #3 on: January 17, 2019, 10:56:55 PM »
Im guessing the sensor for this is the sensor that i have found and moved about recently while replacing the turbo which is found close to the control unit screwed above the radiator?


Thanks for your input. I will go through each of your suggestions tomorrow morning to help narrow down the issue. starting with the external temp sensor.

thanks again

It might be yes - do you have an external temp readout on the dash? My mk1 didn't but was a Ford petrol and Aspen spec so not a good comparison. If its a sensor just on a wire then yes its probabbly that one.

The petrol ones use a fan switch in the upper radiator hose to directly switch the fan on and off, mounted in a plastic collar halfway down the hose. Don't know on the diesels but would imagine its the same (it may be in the radiator - Don't know, but someone here is likely to answer as the diesels are more common)

Offline cravenbiker

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  • Model: Alhambra Mk1
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  • First Name: Tristan
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Re: small coolant leak and fans on constantly when ignition turned on
« Reply #4 on: January 18, 2019, 10:07:57 AM »
It might be yes - do you have an external temp readout on the dash? My mk1 didn't but was a Ford petrol and Aspen spec so not a good comparison. If its a sensor just on a wire then yes its probabbly that one.I don't have temp readout in the car

The petrol ones use a fan switch in the upper radiator hose to directly switch the fan on and off, mounted in a plastic collar halfway down the hose. Don't know on the diesels but would imagine its the same (it may be in the radiator - Don't know, but someone here is likely to answer as the diesels are more common)need to test all of them i guess to find out which one, if not more than one, is faulty

Haynes manual says that engine coolant sensor is on the front of the head. but there is also a sensor in the radiator and on the top radiator pipe halfway between the rad and the head. what are these other sensors for? does the edu take a mean reading of the three of them or just take the reading of the sensor with the least resistance of the three (or am i looking at  this in too much detail?)

Thanks again for your help. really need to get this motor sorted for a trip to the mountains next week!

Offline cravenbiker

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Re: small coolant leak and fans on constantly when ignition turned on
« Reply #5 on: January 18, 2019, 10:21:18 AM »
Also, still seems a coincidence that i have the water leak and the fan is staying on at the same time........Right off to investigate!!

Offline cravenbiker

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  • Model: Alhambra Mk1
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  • First Name: Tristan
  • Region: Non UK
Re: small coolant leak and fans on constantly when ignition turned on
« Reply #6 on: January 18, 2019, 11:06:16 AM »
and just one more thought on this, should the fan stop working when the plug is pulled from the faulty sensor?

Offline johnnyroper

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Re: small coolant leak and fans on constantly when ignition turned on
« Reply #7 on: January 18, 2019, 12:48:27 PM »
My mark 2 the fan was controlled by a temp switch in radiator if I remember correctly,unplugging it stopped the fan from running.
The coolant temp sensor was at rear of engine,canít remember if it had more than 1 sensor or is that did ECU feedback and the gauge?

Offline cravenbiker

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  • Posts: 44
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  • Model: Alhambra Mk1
  • Spec: 1999 1.9tdi 81kw
  • First Name: Tristan
  • Region: Non UK
Re: small coolant leak and fans on constantly when ignition turned on
« Reply #8 on: January 18, 2019, 01:31:22 PM »
My mark 2 the fan was controlled by a temp switch in radiator if I remember correctly,unplugging it stopped the fan from running.
The coolant temp sensor was at rear of engine,canít remember if it had more than 1 sensor or is that did ECU feedback and the gauge?

so pulled the rad sensor cables off and the sensor on the upper rad pipe and the sensor in the flange at the end of the upper rad pipe that enters the cylinder head. Still, the fan runs.

So i may be looking at the rear of the engine to see if i can see another sensor there.
before i do that, would the fan be turned on using a relay? is there a chance that this may be sticking if there is a relay?

Offline brianh

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Re: small coolant leak and fans on constantly when ignition turned on
« Reply #9 on: January 18, 2019, 02:57:27 PM »
I suspect you will find the relays for it are near the battery, screwed to the front crossmember (remove the battery cover if there is still one there, then look towards the front edge of the car behind the headlight on the battery side of the engine bay, its screwed to the front crossmember there). Least thats where mine was, though may be different on diesels. I think its more than just a relay more a basic controller with a relay as part of it.

Offline cravenbiker

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  • Posts: 44
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  • Model: Alhambra Mk1
  • Spec: 1999 1.9tdi 81kw
  • First Name: Tristan
  • Region: Non UK
Re: small coolant leak and fans on constantly when ignition turned on
« Reply #10 on: January 19, 2019, 01:08:09 PM »
Does anyone have a wiring diagram for my car or can anyone tell me where i could find one?
I have opened the rad fan controller (it was mounted at the front of the battery on top of the cross member above the rad) by prizing it open and has 3 connectors and 4 relays inside and with the two connectors that go to the fans connected there is no fan running (the problem I'm trying to solve is the constant running of my fans) but when connecting the smaller of the two connectors one of the relays is activated and soare the fans turned on. managed to check continuity between the cables of the sensor in the radiator to the small connector which is triggering the fans and there is continuity between 2 of the cables of the small controller connector and the rad sensor connectors, plus one of the wires is a negative this leaves one wire that is un accounted for which i think may go back to the ecu but before peeling back the loom to look for shorts in the wiring would like to see where else this wire goes.

any links or downloads would be very helpful.

Thank you

 

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