2.5 V6 heater problem hot>cold>hot

[Roverguest]

Hi,

On the V6 Rover 75, the heater has started going cold, and on investigation it appears (could be coincidence) that when accelerating it warms up, and at times gets nice and hot for a time before going cold again.

Initially I thought perhaps a stuck thermostat but doing the diagnostic shows and engine temperature as I was test driving around local roads around 100 degrees, certainly plenty for a toasty heater.

Coolant level is fine

Thanks in advance

[trikey]

You have an airlock in the system, have a search on here for the correct procedure for refilling the system, this should sort your issue.


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[Roverguest]

Would that be likely despite the car not having had any work done since buying it last week? (when the heaters were fine)

[trikey]

Yes, if it hasn’t been done correctly then it will keep happening until resolved I’m afraid.


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[Roverguest]

Coolant level is same as it was on picking up the car.
Would air only get in with a leak ?

[trikey]

Originally Posted by Roverguest

Coolant level is same as it was on picking up the car.

Would air only get in with a leak ?

No! The coolant level will remain the same with an airlock, the coolant won’t be circulating around the whole system properly.




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[Roverguest]

On a side note, It’s a 02 reg, and I think a 3 speed fan as no visible relay, but no fan kick in until coolant reaches 112 on the diagnostics on IPK.

Fan works with AC

What would this indicate?

[SD1too]

Originally Posted by Roverguest

... and I think a 3 speed fan as no visible relay ..

David, your profile says that you have a 1.8T engine but you are definitely asking about a KV6? Please confirm. By the way, it's not a relay it's a resistor.

Originally Posted by Roverguest

... but no fan kick in until coolant reaches 112 on the diagnostics on IPK.

As Trikey says that usually means low speed failure, or in the case of a 3 speed fan low and medium speed failure, which you should repair immediately. This will involve removing the front bumper.

Originally Posted by Roverguest

Fan works with AC

1. Start the engine from cold.
2. Press the windscreen demist button.
3. Get out of the car and walk to the radiator grille.
4. Is the radiator fan running continuously or is it pulsing on and off periodically?

Please report back asap.

Simon

[Roverguest]

Originally Posted by SD1too

David, your profile says that you have a 1.8T engine but you are definitely asking about a KV6? Please confirm. By the way, it's not a relay it's a resistor.

As Trikey says that usually means low speed failure, or in the case of a 3 speed fan low and medium speed failure, which you should repair immediately. This will involve removing the front bumper.

1. Start the engine from cold.
2. Press the windscreen demist button.
3. Get out of the car and walk to the radiator grille.
4. Is the radiator fan running continuously or is it pulsing on and off periodically?

Please report back asap.

Simon

Hi Simon, thanks for the info!

Yes I have my 1.8t but a friend who is new to discover these great cars got himself a lovely Wedgewood 2.5 auto with Neptune leather.

Just ironing out some foibles and bits, as I have never really touched the V6s before.

Having done a little research and what Trikey says, I have advised he needs to go for the uprated fan which is available on ebay from 75ztspecialist?

Thanks for the advice

[SD1too]

David; I would like you to perform the test I listed because your evidence doesn't point immediately to a straightforward diagnosis. Your friend should not buy anything yet as there is a risk that he could waste his time and money. The cheapest and most reliable solution is to repair the original fan system. Ebay fans will not be "uprated". If a replacement is proven to be necessary, and we don't know that yet, I'd strongly recommend that you take the advice of club members Arctic and Jules.

Simon