Re 1.2 TSI CBZA 4 cy engine.

We had the unfortunate experience of acquiring a car with a blown head gasket, which was from and a fairly badly warped cylinder head. Thankfully the block looks just to be within spec.

Ultimately, 6 thou needed to be skimmed off (0.1524 mm) the head.

My usual independent parts supplier said that no thicker gasket was available. Does anyone know otherwise??

When I calculate the compression ratio change, we go from a 10:1 to 10.21:1

But does anyone have any comment as to the valve timing change we may induce from moving the head closer to the block. I understood on some engines (my vintage car engine for one) this is a point of attention, but I am unsure with the CBZA/CBZB with a timing chain and the usual set up tools, if I should be concerned, or when we lock everything back together the timing is re-aligned.

Sorry for such a technical question.

BTW: All the exhaust valves guides needed replacing, as did the oil pump chain. The old valves and seats were all recut and tested and I presume all the roller tappets will need replacing too. Quite an expensive refurb overall.

Watch out if you have one of these engines with 120k, quite a fiddly job to undertake (for the DIY enthusiast at least)

Has the cause of the gasket failure been established?

E.g. coolant pump failure, thermostat stuck closed (there are two), radiator fan failure etc.?

I don't know the answer to timing question, sorry. I wonder if you could double up on the hg?

Ignore the doubling up suggestion. Would be way too thick.

6 thou doesn't sound like a huge lot, but I'm no expert.

Edited 11 August, 202511 Aug by Breezy_Pete

7 minutes ago, Breezy_Pete said:

Has the cause of the gasket failure been established?

E.g. coolant pump failure, thermostat stuck closed (there are two), radiator fan failure etc.?

I don't know the answer to timing question, sorry. I wonder if you could double up on the hg?

Hi, no idea how it may have failed, the engine temp warning came on after approx 2 hours of motorway driving but I presume the cause here was from the air build up in the coolant once it had blown

I will investigate the thermostats now all is drained, that should be an easy one.

I believe the usual sequence of events is overheating followed by mechanical failure of the head/block joint (loss of gasket compression), rather than the converse.

OK I can see that, I presumed it was just mechanical so I will certainly look further in to the root cause.

I found thicker gaskets in the end.

but all that said, the engine did not run well following the re-build.

Skoda advised the heads cannot be skimmed, and re-fitting the time case cover I can see why as the angled fitting face near the cam cover, the bolt holes did not re-allign upn re-fitting - but a simple elongation of the hole resolved.

However, the head is still blowing, and we have miss-firing, the top is also rather rattly, I fear for the valve clearances now we have machined the head down

I am guessing that it is the end of the line for this car..

So beware - once the head goes in these engines, it is catastrophic,

BTW - the twin theremostat was replaced, not very expensive, I did test the old thermostat insert in a pan of hot water but could not see any mechanical movement when the water reached temperature. But, the radiator fan never came on once the car reached temperature - I presume this was the root cause of the overheating..

This is the first 1.2 TSI with a head gasket failure that i have read of on here.

A salvage engine might well have been a 'simply clever' fix.

Regarding the valve clearances - aren't the TSI cam-followers self-adjusting hydraulic type?

3 hours ago, Ootohere said:

This is the first 1.2 TSI with a head gasket failure that i have read of on here.

A salvage engine might well have been a 'simply clever' fix.

in hindsight yes, quite definitely, and we be my recommendation, we did not appreciate how fiddly and involved it would be, I've done a few head gaskets in the past but this was something else with the timing chain at the heart of the engine, meaning so much more had to be dismantled.
I do not have an engine hoist either, + a gravel drive way, so it seemed a natural challenge to have a go at rebuilding. Also, if you give the valves attention, and check everything else over, the engine should run like brand new afterwards, it always did before.. with my boy at home for the summer and wanting to learn more on his new car... off we set with my trusted socket wrench. We were blissflufy ignorant of how involved the job was, and how many new tools I needed to buy.

I have not been very impressed with the VAG 1.2 TSI engine 😒 I does not seem a serviceable engine, add to the mix the **** timing chain then I do wonder on how many of these cars will ever reach vintage status = zero imo.

3 hours ago, Warrior193 said:

Regarding the valve clearances - aren't the TSI cam-followers self-adjusting hydraulic type?

I put the head back praying they were self adjusting. The manual had no mention of how to adjust, nor how to even measure, I could not even see a way of getting a feeler gauge in anywhere to measure anything anyway. I was keen to just move on and re-assemble and worry about any rattle down the line and why I am a little ultra sensitive to any rattle I think I may hear.

An ex mechanic acquaintance talked about pre-machined units, and a you tube video on this engine in a polo, it was these that was the reason for the re-build failure - but on this there was some valve damage from the pistons too, Slipped timing. So I hoped that this was mechanical damage not related to my re-build.

But not being able to measure anything when we have re-guided and cut the valves/seats, and skimmed the head is unsettling.

So yes, I pray they are self-adjusting..

Timing chain issues with early 1.2 TSI,s and Leads, and from 2013 so 12 years ago so noise complaints.

They are doing quite well in their millions as Euro 5,s and then came the Euro 6 and cam belts.

A damn sight better as far as reliability than many other 1.0 or 1.2 3 or 4 cylinder engines from European Manufactures.

@simonfi How many miles had your engine done, what age was it and how long have you had the car?

Edited 11 September, 202511 Sep by Ootohere

The car had 118k miles, is a 2013 model, and pretty tatty. We only owned it for a day before the temp warning light appeared and we did a head gasket test.

It was bought, thinking for its condition, it was a fair price, it also obviously needed some attention to get the electric window working - which transpired to be several breaks in the wiring loom at the door opening.

Little did we know something was more serious under the bonnet.

Did you trim the pistons and valves according to head?

No, the block stayed in so the pistons were untouched. The valves were cleaned and cut for the new guides that were out of spec.

Aside of the misfire, on 1 and 3, which could be the valves/injectors, we have gasses coming up through the coolant which turn the head gasket testing kit a different colour - i.e. the head is still blown. The Cylinder head apparently passed a pressure test but I guess the block was out of spec enough all along, or we had some other unknown rebuild muck up along the way.

Perhaps a new engine is needed now, or we scrap. TBH I do not have the time to work on this now.. Anyone fancy a cheap project?

Edited 27 October, 202527 Oct by simonfi