Volkswagen Passat B8 - 2.0TDI BlueMotion - Intermittent Engine Overheat

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Mon 29 Apr 2019 22:59
Volkswagen Passat B8 - 2.0TDI BlueMotion - Intermittent Engine Overheat - Philflies

Hi,

VW Passat B8 Bluemotion Saloon, 2015, 94k miles.

My Passat is intermittently overheating, about once a week but under quite specific circumstances. The temperature gauge is initially rock steady at 90c and only whilst on motorway or fast dual carriageway around 15mins into the journey (from cold) the temperature will climb past 90c and upto 120+c fairly quickly.

If I notice it happening early enough and give the engine some higher revs 3000-4000rpm it seems to sort itself out, temperature will return to 90c and will be fine for the rest of the journey. It may not occur again for a week or so. It has not happened while doing slower, town driving type journeys.

Could it be the thermostat sticking closed? or maybe the waterpump giving in?

I've got it booked in with the garage to be looked at but want to be armed with some prior info if anyone out there can help please?

Thanks in advance.

Phil

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Tue 30 Apr 2019 01:25
Volkswagen Passat B8 - 2.0TDI BlueMotion - Intermittent Engine Overheat - elekie&a/c doctor
I suspect the temporary overheat is when the dpf is in regeneration mode.
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Tue 30 Apr 2019 15:13
Volkswagen Passat B8 - 2.0TDI BlueMotion - Intermittent Engine Overheat - Philflies
I thought that too originally but a couple of times it’s made it to the red line, I’ve then got a beep and an overheat warning on the dash. I thought I’d also read that when the dpf is doing its regen you get a symbol on the dash?

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Tue 30 Apr 2019 15:36
Volkswagen Passat B8 - 2.0TDI BlueMotion - Intermittent Engine Overheat - dieselnut

I think this engine has the electric coolant pump sleeve.

It restricts coolant flow with an electrically operated sleeve until the engine reaches normal operating temperature, the idea being to improve engine efficiency.

Problem is that the sleeve sometimes sticks closed & stops coolant flow, then frees itself.

I belive VW will replace the pump FOC if you have a word with them.

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Wed 1 May 2019 14:25
Volkswagen Passat B8 - 2.0TDI BlueMotion - Intermittent Engine Overheat - Philflies

Thanks for that info, much appreciated.

Having got to the point where it's overheated and come up with a warning on the dash will that have left a fault code anywhere?

Being an intermittent fault you can guarantee it won't perform when it's at the garage!

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Wed 1 May 2019 15:19
Volkswagen Passat B8 - 2.0TDI BlueMotion - Intermittent Engine Overheat - elekie&a/c doctor
If the car is fitted with an on demand water pump, not sure if this would flag the mil light if in trouble . It is only a 2 wire electro magnetic device, so would need to be open or short circuit to bring the light on . If it is stuck mechanically, the ecu can’t see that.
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