cooling issue

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m3ag
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cooling issue

Post by m3ag » Thu Aug 29, 2019 11:32 am

Separate thread for my cars issue, and its no doubt been covered before

6n2 GTi issue is:

Bought it as a car that had suffered an overheat a few months ago, we inherited a damaged header tank (looks to have been butchered) and very little coolant, apparently the car was left standing for 30mins ticking over, no fan kicking in meant it boiled over.

So, the fan didn't run, but does now (new fan), new header tank and cap, flushed the system best we could.

Symptoms now are

Refill the cooling system via the header tank, run the car up to temp, top hose getting hot, heater blowing hot, bottom hose still cold/barely warm. Can feel pressure in the hoses, and the return feed is pumping through into the header. After about 15mins running at approx 2k the coolant starts to boil in the header tank and starts to escape via the tanks outlet point. Bottom hose still not hot but coolant warning light comes on.

The cars history shows it had a new VAG thermostat in Sept 2018, but not the housing. Not fitted by VW but by a local garage.

So we'll pull the stat out and re-run the car without to see if this resolves the issue.

Engine runs nice, no mayo, oil is clear.

So we believe the stat isn't opening for whatever reason or is stuck as such its boiling up. I can't add any more coolant in either and we're running it with the cap on now as coolant was just spurting out with it off.

Could the car overheating like it did damage the stat?
Is it best to replace the stat and the housing at the same time, obviously best off using genuine vw parts, or could we just have a major airlock, if so so how does that get shifted?

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937carrera
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Drives: 2000 Polo GTi
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Re: cooling issue

Post by 937carrera » Thu Aug 29, 2019 8:08 pm

It sounds like the coolant isn't circulating, I doubt it's an airlock.

Time to check water pump and for blockage in the radiator, did you flush that through properly ?

Be careful with removing thermostats, sometimes the design of them means that coolant does not circulate as well when they are removed, but you already have a problem.

I haven't seen any signs of a blown HG from your description, so I doubt the overheating has caused major damage

m3ag
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Re: cooling issue

Post by m3ag » Fri Aug 30, 2019 11:59 am

flushed it again and runs clear however we took the stat out. OMG talk about ruined, the bridge has failed and the stat has fallen apart so new parts ordered from vw for fitting later today. The original would not be letting anything through in a hurry.

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937carrera
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Drives: 2000 Polo GTi
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Re: cooling issue

Post by 937carrera » Fri Aug 30, 2019 12:41 pm

:D

I read above it had a new VAG thermostat last year, but maybe it wasn't VAG ?

Anyway, looks like you have identified the problem. Nice cheap fix and GTi :D :D :D

m3ag
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Re: cooling issue

Post by m3ag » Fri Aug 30, 2019 1:24 pm

yes, found the receipt, Vindis VW. Supplied Sept 2018, fitted a week later and the part number matches up OK but looking at the flange/bridge etc that doesn't appear to have a part number and thats the part that has caused the issue I think.

m3ag
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Re: cooling issue

Post by m3ag » Tue Sep 03, 2019 2:55 pm

all sorted, it was the stat and the housing, car running great so happy bunny.

Thanks for the pointers and the suggestions, all helps you know....

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937carrera
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Drives: 2000 Polo GTi
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Re: cooling issue

Post by 937carrera » Tue Sep 03, 2019 3:17 pm

It's a pleasure, time to put some pictures up :wink:

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