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Old 25th May 2019, 19:01   #1
chillyphil
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Default KV6 overheating

Mg zt-t 190.

Hi all,

Out and about last night when the engine overheat flashed on the IPK for a few seconds and went out.
The engine temp indicator maxed, then slowly returned to normal.
Luckily I was at the top of the hill, so in neutral with the engine idling, I managed to get home without any serious overheat.

This morning, put around 3 litres in the system, bled it on the engine hose, and started up.

Looking at the torque ap, temp rose to normal, then slowly crept up to 96.

After a few minutes I revved the engine to 3000rpm for a moment or two, the temp went up to 102.
I shut it down.
During this routine the high speed fan on the rad came on and off sporadically.

When the engine was off and cooled to around 70, I turned on demist, the interior fan came on, but the rad fan didnt, same happened when I tried the air con on lo.

I didnt seem to lose any fluid during this time, even when the temp went over 100 so I am assuming the thermostat housing is ok?

Any thoughts on the cause before I start messing around and making it worse?

Phil
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Old 25th May 2019, 19:13   #2
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is your fan working properly.i think you may need a new resistor or new bushes sorry didnt check age of your car.

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Old 25th May 2019, 19:31   #3
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Your radiator fan should come on low speed at around 100 and stay on until 95. If it doesn't then you have a problem with the fan, that could be a failed resistor, relay or fan brushes.
Regardless of this your car shouldn't overheat just because of a failed slow speed fan, the next speed should come on at around 106 and cool the engine.
It could be a combination of a failed low speed fan and a sticking thermostat.

1st job is to find out if you have a 2 or 3 speed fan.
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Old 25th May 2019, 20:00   #4
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Thanks Dave and Gordon,

How do I check what fan set up I have?

It's an 03 reg.
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Old 25th May 2019, 20:52   #5
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Quote:
Originally Posted by chillyphil View Post
Thanks Dave and Gordon,

How do I check what fan set up I have?

It's an 03 reg.
Look through the grill at the front, behind the fan at approx the 2 o clock position you will see a silver resistor around 15mm x 15mm x 70mm (ish)
if not it is (almost) certain you have the older type 3 speed fan.
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Old 25th May 2019, 21:07   #6
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Hi Phil,

Quote:
Originally Posted by chillyphil View Post
... put around 3 litres in the system, bled it on the engine hose ...
3 litres is a lot of coolant to lose. Remove the engine acoustic cover and check the 'V' for leaks from the thermostat housing 'O' ring.
When you bled the cooling system, did you raise the expansion tank with the engine not running?
Quote:
.. the temp went up to 102 ... the high speed fan on the rad came on and off sporadically.
That sounds like a 2 speed system with a failed resistor, but I await your confirmation that you have a resistor.
Quote:
I didnt seem to lose any fluid during this time, even when the temp went over 100 so I am assuming the thermostat housing is ok?
Don't assume Phil, look into the 'V' and find out for sure.

Simon
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Old 25th May 2019, 23:37   #7
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Thanks Simon and Dave, I'll make those checks tomorrow PM, when I return from work, and post the results.
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Old 26th May 2019, 09:31   #8
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Phil; it's also important that we address this:
Quote:
Originally Posted by chillyphil View Post
... put around 3 litres in the system, bled it on the engine hose ...
Quote:
Originally Posted by SD1too View Post
When you bled the cooling system, did you raise the expansion tank with the engine not running?
MG Rover's official procedure for the KV6 specifies raising the expansion tank. If you didn't do this, you risk introducing an air lock. You'll be able to find this procedure in many posts of mine but let me know if you have difficulty.

Simon
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Old 27th May 2019, 18:09   #9
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Managed to have a look at the fan this afternoon.
There is no resistor visible.
There are the two screw holes on the housing which look like where the resistor should be.

Started the engine and left it on idle.
Engine temperature climbed to 96, fan didn't come on.
Temperature climbed to 107, still no response from the fan.

I bottled out then and turned the demist on.
The fan came on and the engine temperature quickly dropped to 102 within around 1 minute.

Leaving the demist on and fan running, the temperature dropped to 96 within six minutes.

It then continued to hover between 96 and 97.

Any thoughts.

Phil
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Old 27th May 2019, 21:11   #10
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Hi Phil,

Thanks for the test results. However, my diagnosis depends upon your answer to my earlier question:
Quote:
Originally Posted by SD1too View Post
When you bled the cooling system, did you raise the expansion tank with the engine not running?
Can you let me know whether or not you did this please? It's very important.

Simon
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