Stupid flashing coolant light!

[Andystewart 10]

Morning all. My annoying coolant light won't stop flashing. So, I changed the expansion tank Thursday eve, light went out, great, simple fix. Saturday light came on, topped up thinking it was a air lock releasing, light went out. Great. Went for a hour drive to see friends, all fine. Vet in the car to come home, coolant light flashing, but levels all good!? Checked connectors, all good, but this morning noticed oil in coolant (hoping it's just the heat exchanger) but why would my light still be flashing? New tank worked at first so wouldn't think it's that, any ideas? Could.....it be the oil in the coolant now stopping the sensor working?

Thanks guys.

[Jon_vr6 1]

Where did you get the new coolant tank from?

 

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[volksworld13 0]

I think the oil will cause the issues in the header tank , I know it's a different car but a Peugeot had a head gasket gone and oil in the header tank caused the cookant light to come on a few weeks ago when I looked at it.

[fendervg 33]

The two terminals I. The sensor form a circuit via the coolant. If the level drops, the circuit is broken, hence the light goes on.

 

Check the wiring to make sure it is working and bridge the pins on the connector. You might have a dodgy tank.

[Andystewart 10]

Yeah think your right, but a wire between the connectors and lights out! Annoying as the tank worked at first. Maybe it is the oil in the coolant coating the pins for the sensor in the tank and preventing the water making contact. So, to address the oil, I've search on here and it seems, oil in the water suggests heat exchanger! Well, first port of call at least, am I right?

Thanks for the help guys,

[Supercharged 2]

Assume it wasn't a genuine tank?? unfortunately many of us have had issues with pattern ones, they usually work for a few months though before they fail, not a day :-)

[Jim 2]

Not to try and suggest the worst case scenario but oil in the water could also be a sign of the head gasket going / gone :(

[ChrisL 20]

I bought a new genuine VW expansion tank only because the old one was grubby and had it fitted by vw. This soon after started flashing, it was the pins in the bottle causing the problem

[Jon_vr6 1]

Assume it wasn't a genuine tank?? unfortunately many of us have had issues with pattern ones, they usually work for a few months though before they fail, not a day :-)

Some Genuine ones had the same problem

 

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[Andystewart 10]

Yes pattern part, lesson learnt! But glad I didn't spend out on a genuine part now as the new one has oil in it! Head gasket is always at the back of my mind, but hoping, wishing, wanting it to be the heat exchanger. Now mayo on oil cap or dip stick and no loss of performance (other than it ran lumpy the other day on start up out of the blue, but not happened again) so, new heat exchanger first, and alot of praying!

[Jim 2]

Also had flashing coolant light from pattern part (GSF) coolant bottles. Think I went through two in fact before getting an OE one and, low and behold, it was fine!

 

Like you say it could very well be just the oil cooler / heat exchanger - so certainly worth checking / swapping. Is it a 2.0 16v?

[Andystewart 10]

No it's a VR6.

I can seem to add a pic, but I just found something in the old tank. What looks like a broken plastic ring approx 35mm

[Andystewart 10]

Ok forget that it appears to be a broken part off a old cap. Few. Will take exchanger off tomorrow and pressurize it under water as suggested on here somewhere. Let's hops

[seanl82 23]

I have a genuine one that has been doing it since new too. :(

[Jon_vr6 1]

I have a genuine one that has been doing it since new too. :(

Yeah there was a bad batch happened to me and had to buy another been ok since.

 

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[seanl82 23]

Obsolete now unfortunately.....................

[Jon_vr6 1]

Obsolete now unfortunately.....................

Even from vw classic parts germany?

 

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[seanl82 23]

Even from vw classic parts germany?

 

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Thats direct from VW, but I'd imagine so from Classic Parts too. I know Heritage don't list it, but do for the 16v etc....

[Andystewart 10]

Evening guys, so, I've now changer the oil heat exchanger. Took the old one out and tried the pressure test, but I'm not 100% happy this was the cause, I could only get a few bubbles under water and I'm not sure if this was just the trapped air. So anyway, I changed it, dropped the oil (all looked good with no signs of water) put a cheap oil back in to flush through for a few days, (also thought if the problems not solved I've not wasted good oil) put a flush cleaner through coolant, emptied and refilled. Took for run and so far so good.....but I'll keep an eye on the water over the next few days. Your prayers that it's not HG will be much appreciated.

[Jim 2]

I'll light few josticks, and say a prayer to Wilhelm Karmann!

[Andystewart 10]

Soo, seems I may have oil in my nice fresh coolant again! I did a coolant flush, and connected the garden hose to give it a good wash through. And today I put my finger in the coolant tank and pulled out a little oil!! Dam dam dam dam dam! Going to watch over next few days just in case, just.....in case there was still a little bit left in the system! Anyway, been searching and looking a pictures, and wondering where on the head gasket the problem could be, where do the oil and water come close? I've not had the pleasure of removing a vr6 head before, so does anyone have a diagram of the block labeling the oil veins and water veins (if you can call them that).

Thanks