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Old 20th October 2019, 21:16   #1
Typhoon190
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Default V6 thermostat running temperature

Has anyone replaced the thermostat on their V6 with the latest batch of 'genuine' housings at all please?

I thought that the running temperature was 90 degrees C +/- 3 degress?

The first one I fitted was running around 83. I've fitted another one and it's running around 81?

I let the temperature build to 93 at idle, but it still fell to 81 when I drove round?
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Old 21st October 2019, 14:55   #2
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Hello Ben,

Your running temperature should be in the low nineties when the car is moving. When stationary it may slowly rise to a maximum of 100 degrees.

The specification of the thermostat is that it begins opening at 88 degrees +/- 2 degrees and is fully open at 96 degrees.

Temperatures in the low eighties suggest that the thermostat is stuck open. I'd suggest that you change your supplier to a recognised X-Part dealer.

Simon
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Old 21st October 2019, 19:00   #3
Typhoon190
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Hi Simon.

Pretty sure I had.

First kit purchased from E-Car parts, and second from DMGR's. Both marked up MG Rover.
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Old 21st October 2019, 19:48   #4
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OK. I have no experience of DMGRS but I know that E Car Parts of Sandy, Bedfordshire is an X-Part dealer because I bought my last thermostat from them.

What method are you using to measure coolant temperature; the built-in IPK diagnostics or a third party device?

Following your work on the cooling system, are you refilling and bleeding according to the official MGR procedure?

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Old 21st October 2019, 20:33   #5
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Quote:
Originally Posted by Typhoon190 View Post
I thought that the running temperature was 90 degrees C +/- 3 degress?
That sounds about right to me.


Quote:
The first one I fitted was running around 83. I've fitted another one and it's running around 81. I let the temperature build to 93 at idle, but it still fell to 81 when I drove round?
My advice Ben, is to get back to Mat and he'll replace it without quibble. It's clearly not performing as it should. I'm not sure what the latest batch with a 'genuine housing' means though. Maybe E-Car parts supplied you with the same batch? Good luck.


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Old 21st October 2019, 23:08   #6
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Thanks for the replies.

I've had to bypass the oil cooler for the moment, as it's leaking oil into the coolant, but the thermostat would still control the engine temperature I would have thought?

I'm using the OBD through the odometer, so the only other thing would be the temperature sensor, but it's not erratic.

My blue ZT-T190 behaves perfectly. Stays pretty much spot on 90 degrees once up to temperature.
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Old 22nd October 2019, 09:07   #7
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It's the thermostat. There's another thread on low running temp from a recent stat replacement.



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Old 23rd October 2019, 06:41   #8
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Thanks TC. 3rd time lucky then. This really doesn't help with keeping these cars on the road if brand new 'genuine' oem parts are faulty out of the box.

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Old 23rd October 2019, 10:03   #9
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I doubt it's faulty in the strictest sense. It simply has a lower than normal opening temperature. Thermostats come in a small range of settings, the 75/ZT being a nominal 88C. In the petrol engines, this gives a typical running temperature in the 90-95C area. For these cars it should be the 88C type.



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Old 23rd October 2019, 10:11   #10
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A couple of years ago my thermostat cracked catastrophically, managed to get the car home eventually (many stops to let it cool down) with no overheating damage. I fitted a full thermostat kit from Matt, bled using the approved procedure. No issues afterwards, heaters warm, no coolant loss. However the normal running temperature fluctuated between 81 and 84 degrees, no-where near 96 degrees as been suggested is the norm. As said I have had no issues...until recently! Coolant level low, topped up but evidence of leakage from the expansion bottle cap. A couple of days later while sat in traffic I saw steam from under the bonnet, checked OBD and temperature was at 107 degrees before the fan kicked in.

Further investigation found the fan low speed was kaputt, and the high speed kicked in just as the expansion bottle cap would let go, also coolant in the 'vee' due to a hole in the straight pipe between the pump and the thermostat.

I have ordered another thermostat kit from Matt, along with a gold resistor to restore fan low speed operation, when fitted I will report back regarding the running temperature and see how it compares.

Edit: The expansion tank cap has 140 on the top, is this the temperature at which it opens? If so would it be wise to replace this too, seeing as it is opening at 107 degrees, or could the pressure at this temperature have been sufficient to open it?
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Last edited by Dubya; 23rd October 2019 at 10:14.. Reason: Added expansion cap question.
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