Cylinder head corrosion

[93URS4Avant]

I have just done something similar - didnt have decent anti-freeze in which resulted in pressure coming back up to the header tank and out via the pressure cap. The hea dis off - with no 'smoking gun' as such. I am unsure whether the head has to be skimed - or whether the replacement gasket set plus bits will do...? I am reading with interest....

[220bhp]

I have always used g12 but have had lots of running issues with this car.

[Flat on my back]

.

That is quite severe corosion, look for a second hand head.

[220bhp]

I think that given that most of these heads are nearing twenty years of use, that mine
will not be the worst one out there, given the fact that I know the history, so I think this thread will be of more use to people in time to come.
I have placed the new metal gasket over the head and it is plain to see that the head gasket will seal on all important arriers. My main concern in using it would be the fact that it has just had its second skim and what affect it will have on raising the compression.
I would like to hear from anyone that has had a problem regarding compression or any other related issues.
Thanks for all your comments to date.

[220bhp]

I have had the head checked and they say it will be fine,until I told them I intend to fit an RS2 turbo and up the boost, then they where a bit unsure, so I think I will sorce another head to be safe.
I had a couple of offers of aby/ ann heads but I am not sure if they can be machined to take a dizzy, also a couple of 7a heads,
Before I make a dissision I just wondered what anyone else has to offer, I have to say I would prefer a complete 3b head but I would consider any thing else on offer.

[Acidburn]

aby/aan should have a blanking plate for the dizzy opening.

You will find that the aby/aan you will probably find cracks in them as well as most have had years of boost running thru them.

same with 3b heads. I looked at quite a few when I was after one.

[driftin jo]

That corrosion is caused by the coolant being acidic , this can be for several reasons .

If the engine was fitted with Propylene glycol antifreeze and the system for some reason was letting air in to it through a bad header tank cap or other leek such as a hose or head casket .
The problem with Propylene glycol type antifreeze is that when it is exposed to air and heat it causes oxidization and forms lactic acid that can eat your cylinder head .

For this reason I would not recommend ever using Propylene glycol type antifreeze, if you are unsure of what is in your car then dump it and use Ethylene glycol type antifreeze.

If the coolant has been in the car for a long time and the system is not perfect then the anti corrosion compounds can be used up and the coolant can become acidic , all this “G12 is fitted for life of the car” is just nonsense to me as an old car is not very likely to have never had work done on it by a non vw/audi garage and by all accounts even a little bit of none G12 antifreeze added to G12 can totally mess it up and cause it to end up acidic.

I just dump mine every 2 years ,usually sooner if I've been working on it and replace with Ethylene glycol type.

[add]

I have to say I would prefer a complete 3b head but I would consider any thing else on offer.

I have a bare 3b head,with no cracks in it....