Head gasket failure ?

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littlepolo
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Posts: 500
Joined: Thu Jul 21, 2011 9:47 pm

Re: Head gasket failure ?

Post by littlepolo » Mon Nov 04, 2019 8:29 pm

How long have you had the vehicle and is the history known?

Looking at the photos it seems that the problem is related to the mating surfaces, especially if the gaps are close to tolerances.

How did you test for flatness? A dial gauge would indicate any run out precisely.

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937carrera
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Posts: 375
Joined: Sat May 17, 2014 8:19 am
Drives: 2000 Polo GTi
Location: North Yorkshire

Re: Head gasket failure ?

Post by 937carrera » Mon Nov 04, 2019 11:59 pm

Time for a bit of an update (I have has the car 6 years / 32,000 miles):

The car is running again.I spoke to a garage I use and they had more faith in my abilities than I did. Convinced I had fitted the replacement head correctly they told me to give her a run.

Everything seems OK, temperatures are being managed properly, there is no pressurisation of the coolant and the engine seems a bit punchier than before.

The only negative is that she seems to burn a bit of oil when started. I think the replacement head (unknown history) has a valve stem oil seal / guide problem. Alternatively my light hone has disturbed the fit with the rings and they need to be run in again. On the road she seems to be running fine.

The coolant I was seeing was obviously just normal condensation, and the oil on the plugs was simply the result of the cold start with the oil vial the guides / rings.

I think that on the first assembly I didn't get the head bolts tight enough to seal with the slight head distortion. On the second assembly it probably was just about sealed correctly, but at that time I didn't know that the thermostat housing was broken, meaning the thermostat was not opening.

The head off the car was measured with a steel rule and feeler gauges. I do have a dial gauge but not the suitable surface to mount the head on to get sufficiently accurate measurements. The head will go away for a light skim at some point, probably a pressure test too.

I now know the failure was caused by the low speed fan resistor failing and the thermostat housing at the same time.

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937carrera
Silver Member
Posts: 375
Joined: Sat May 17, 2014 8:19 am
Drives: 2000 Polo GTi
Location: North Yorkshire

Re: Head gasket failure ?

Post by 937carrera » Tue Nov 05, 2019 7:22 pm

.............. and another 12 months test today :D :D :D

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