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The 75 and ZT Owners Club Forums (https://www.the75andztclub.co.uk/forum/index.php)

- Technical Help Forum (https://www.the75andztclub.co.uk/forum/forumdisplay.php?f=11)

- - B operation (https://www.the75andztclub.co.uk/forum/showthread.php?t=297755)

charlie 22

24th July 2019 09:12

B operation

Sorry if this is a silly question but on my kv6, and with this very hot weather should the fan keep going after the engine has been switched off.
It does feel uncomfortable that the temp when the engine is switched of at 100c plus and will sit there rather than the fan continue to curclurate the coolant to a much more acceptable temp.

Sent from my SM-G955F using Tapatalk

SD1too

24th July 2019 09:51

Quote:

Originally Posted by charlie 22 (Post 2750003)

Sorry if this is a silly question but on my kv6, and with this very hot weather should the fan keep going after the engine has been switched off.

It's not a silly question Charlie and the answer is no, it shouldn't.

Quote:

.. the temp when the engine is switched of at 100c plus ...

That tells us that you have a fault. The KV6 should run below 100 degrees C. I suggest that you perform the 'demist test' immediately. With the engine running from cold, press the 'windscreen demist' button on the air con./heater control panel. Now get out of the car and walk to the radiator grille. Is the fan running continuously?

Whilst you're there, can you see a rectangular silver resistor on the fan shrouding at about the two o'clock position?

Charlie, you must take action immediately on this. Your engine is getting too hot. Please report back.

Simon

T-Cut

24th July 2019 10:00

It's caused by heat soak. When the engine's very hot and you turn it off, the head/block contains a lot of residual heat that can cause stagnant coolant to boil in the head. The resultant pressurisation will cause discharge through the header tank cap. To compensate, the cooling system is designed to run the radiator fan for up to ten minutes without the ignition. This chart gives all the parameters.

https://www.mediafire.com/convkey/4b...1flzbr4u6g.jpg

Note that this data is for the earlier 3-speed fan system. The later 2-speed does similar things.

TC

SD1too

24th July 2019 11:53

So as you can see from that chart Charlie, your coolant is reaching 115 degrees which is much too hot. It suggests that your fan's low speed has failed hence the tests I've suggested. I look forward to your response.

Simon

charlie 22

24th July 2019 17:18

Quote:

Originally Posted by SD1too (Post 2750013)

It's not a silly question Charlie and the answer is no, it shouldn't.

That tells us that you have a fault. The KV6 should run below 100 degrees C. I suggest that you perform the 'demist test' immediately. With the engine running from cold, press the 'windscreen demist' button on the air con./heater control panel. Now get out of the car and walk to the radiator grille. Is the fan running continuously?

Whilst you're there, can you see a rectangular silver resistor on the fan shrouding at about the two o'clock position?

Charlie, you must take action immediately on this. Your engine is getting too hot. Please report back.

Simon

Evening have just done the demist test and the fan runs continuously. I have also have a gold resister fitted as well.:bowdown:

charlie 22

24th July 2019 17:25

Quote:

Originally Posted by T-Cut (Post 2750019)

It's caused by heat soak. When the engine's very hot and you turn it off, the head/block contains a residual lot of heat that can cause stagnant coolant to boil in the head. The resultant pressurisation will cause discarge through the header tank cap. To compensate, the cooling system is designed to run the radiator fan for up to ten minutes without the ignition. This chart gives all the parameters.

https://www.mediafire.com/convkey/4b...1flzbr4u6g.jpg

Note that this data is for the earlier 3-speed fan system. The later 2-speed does similar things.

TC

Hi if I am reading the table right the fan should stay on for ten min above 115c. I have one of the ezze temp gauges and started beeping at 111c the fan stated brought the temp down to 97c. I switch off the engine and fan does not stay on.

T-Cut

24th July 2019 19:08

Quote:

Originally Posted by charlie 22 (Post 2750127)

You're not reading the table correctly.

The condition for the Heat Soak regime (the 10 minute fan) requires the engine to be switched off. With the engine running, as you describe, the other four conditions apply. In this case (at 115C), the fourth condition (fast speed) would be invoked.

TC

SD1too

24th July 2019 22:35

Quote:

Originally Posted by charlie 22 (Post 2750126)

... have just done the demist test and the fan runs continuously. I ... also have a gold resister fitted as well.

OK, thanks. What's the coolant level in the expansion tank?

Simon

charlie 22

25th July 2019 06:56

Quote:

Originally Posted by SD1too (Post 2750214)

OK, thanks. What's the coolant level in the expansion tank?

Simon

The coolant level was below the min, had to put in approx 100ml to reach max. The coolant levels have always had a mind of there own since I had the metal thermostat fitted. Some times they are fine then the next I have to add a little to bring back to the max level. I have had my mechanic do a pressure test and could not find a leak in the system.
I think I will have to start calling my car Christine :D.

SD1too

25th July 2019 09:52

Quote:

Originally Posted by charlie 22 (Post 2750248)

The coolant levels have always had a mind of their own since I had the metal thermostat fitted.

Ahh. When that was done, I wonder whether the cooling system was filled and bled according to the specific MG Rover procedure. If not, you may well have some air remaining which is known to cause level variations at the very least.

Simon

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