Oh jeez, where do i start?

[lida]

Originally Posted by tourer

Any updates?

Hello Tourer, The erratic temp continued, and I observed it in real time thru the diagnostic. Two weeks ago, while driving, the diagnostic screen suddenly registered -128 degrees, the temp gauge on the dash became disabled dropping to the resting position, and the 2nd speed cooling fan came on. On reaching home I switched off car but fan kept on running. I waited 25 mins and then had to disconnect battery - the only way to stop the fan.

I'm assuming the culprit is the coolant temp sensor and it has now totally failed. Apparently if the ECM does not receive an engine coolant signal it will indicate to the CAN bus that it cannot supply the engine temp. I understand that, but why would the fan stay on after car ignition is off ...... open circuit?

Anyway, I am sick of explaining to garages that the temp gauge on the dash will always remain at just under half-way and should not be taken as a sign that all is well (the only time the needle will rise is when radiator is in dire need of water). It's a feature of the KV6 as we know.

She's not been used since then - too risky because the cooling fan being on all the time is drawing more energy than the alternator can generate back to the battery.

[stocktake]

Whilst it is true that the rad fan would remain on after the keys have been removed in an overheat situation I have yet to know one stay on for 25 mins.

It is also correct that if the temp sender fails to send a signal then the rad fan is also activated but I am under the impression this is only whilst the ign is on.

In most cases where a rad fan is operating all the time (key in or key out situation) it has been because the relay in the relay box has failed and remained in the energised position.

More than happy for anyone to advise me if I have this wrong?

[lida]

Hi Stocktake, If the second culprit is the relay, is this an electrical failure or of a component?

[dave lincs]

Hi Lida sorry your car is still not sorted think most of us had assumed Simon had sorted it for you, If you are stuck and have breakdown cover bring it up to me and I will sort it for you

Dave

[stocktake]

Originally Posted by lida

Hi Stocktake, If the second culprit is the relay, is this an electrical failure or of a component?

It is the most likely component failure but I fear it is not your only problem, but one brought about by constant requirement.

[SD1too]

Here's an update from me for followers of this thread.

Lida telephoned me earlier this month to report the erroneous temperature gauge reading and the constantly running fan. At my request she carried out a few tests and I concluded that her slow speed relay contacts had fused in the "made" position. It also appears that the coolant temperature sensor circuit is faulty. During our engine inspection together in the spring we noticed that the ex-MG Rover main dealer had routed the wiring harness from this sensor incorrectly. Instead of crossing the 'V' towards the rear of the RH bank of cylinders, the garage had laced the wires in a spiral around a coolant hose in the direction of the throttle body and it is possible that any consequent damage to the conductors is responsible for the apparent erratic signal to the ECM. I was not able to locate the connector in this circuit without dismantling.

In the spring I had offered to take Lida's car to dismantle and inspect the work done by the garage in an attempt to reach a reliable diagnosis and carry out the necessary repairs. She appeared to want more time to consider her next move and I did not hear from her again until her recent phone call. I very much regret that, owing to other major projects, I am unable to take her car at the moment. I therefore recommended that she takes it to Lates who is best placed to help her. I have the impression that she is giving this suggestion consideration.

Stocktake's posts above are very helpful and I agree with his thinking.

Simon

[lida]

Originally Posted by dave lincs

Hi Lida sorry your car is still not sorted think most of us had assumed Simon had sorted it for you, If you are stuck and have breakdown cover bring it up to me and I will sort it for you

Dave

Thank you Dave, but as the cooling fan is constantly on, it is too risky to drive her any significant distance. The fan uses far more power than can be replenished back to the battery. Lates is too far away, and Russell at MG Rover Solutions in Kent said he wasnt interested (too far), though I thought he was running a mobile service and I would have paid him travelling time.

[slovcan]

Originally Posted by lida

Thank you Dave, but as the cooling fan is constantly on, it is too risky to drive her any significant distance. The fan uses far more power than can be replenished back to the battery. Lates is too far away, and Russell at MG Rover Solutions in Kent said he wasnt interested (too far), though I thought he was running a mobile service and I would have paid him travelling time.

Hi folks. This bit I put in bold in Lida's post has me baffled. The alternator ought to be putting out over 14 volts. That should be plenty to run the cooling fan non-stop while driving the car - maybe with the exception of hours of stop and go urban driving. If that were the case, maybe turn the high draw electrical things off for the trip to Lates. You know, things like the heater, blower on low, electric window defrost, etc.

[SD1too]

Originally Posted by slovcan

Hi folks. This bit I put in bold in Lida's post has me baffled.

Me too Glenn because I did advise Lida on the telephone that when the car is being driven the alternator will generate sufficient current to run the fan continuously at slow speed. MG Rover would have made sure of this for drivers who use the air conditioning on every trip.

Lida's probably wary because her battery was depleted, as you'd expect, when the fan ran continuously for half an hour with the engine stopped.

Thanks for pointing this out Glenn.

Simon

[lida]

Originally Posted by slovcan

Hi folks. This bit I put in bold in Lida's post has me baffled. The alternator ought to be putting out over 14 volts. That should be plenty to run the cooling fan non-stop while driving the car - maybe with the exception of hours of stop and go urban driving. If that were the case, maybe turn the high draw electrical things off for the trip to Lates. You know, things like the heater, blower on low, electric window defrost, etc.

Thank you for your post. Two people have told me it is a journey they would not do themselves. One of them was an RAC man. I hardly ever use high-draw electrics in that car, not even the heater. I just would not travel 85 miles, esp. as I do not have nationwide breakdown.

I bought a temp sensor from Mat at Discount Rover, as well as a windscreen washer grommet in case that is the cause of a leaking reservoir - though I suspect it's the reservoir itself, which Mat says is pricey.