Refitting Head onto Block

Been a newbie regards to working on engines beyond a simple service, i get stuck and need help, i understand the components what they do etc.

So my question is, what good common practices should i do when building the head back onto the block.

junkie wrote:Been a newbie regards to working on engines beyond a simple service, i get stuck and need help, i understand the components what they do etc.

So my question is, what good common practices should i do when building the head back onto the block.

Are we talking about just refitting it or as in rebuilding a fully stripped head, and refitting valves, cams etc?

Were just talking fitting the head, i have new gaskets bolts etc, but is there some things that i dont know about that i need to do, you know tricks of the trade kind of things.

junkie wrote:Were just talking fitting the head, i have new gaskets bolts etc, but is there some things that i dont know about that i need to do, you know tricks of the trade kind of things.

Well, talking from my massive experience of changing one cylinder head, just make sure the block and head faces are very clean and have no bits of head gasket left on them. Time both bottom end and top end up to the marks on both cylinder head and block before refitting and that's about it really. The rest is just general spannering

Cool, its already timed from when i took it off and its a metal head gasket, im not too sure if i need to use any forms of paste anywhere.

Any good tips for cleaning the valve faces.

Oh and also once its all torqued up do i need to run the engine to temp and then re-torque again on the head bolts, sure i heard that somewhere.

junkie wrote:Cool, its already timed from when i took it off and its a metal head gasket, im not too sure if i need to use any forms of paste anywhere.

Any good tips for cleaning the valve faces.

Oh and also once its all torqued up do i need to run the engine to temp and then re-torque again on the head bolts, sure i heard that somewhere.

If corrosion on the head, normally around the waterways, is evident then you will possibly need some special paste that can be applied (liquid metal IIRC). This then needs to be machined back flat at an engineering firm. Can you sling up a piccie of the head so we can have a look?

As far as cleaning the valve faces, petrol is a good solvent, and should get most of the crap off, or even some POR15 degreaser and a plastic wired brush, like a hard toothbrush.

As far as running it up to temp then re-torquing it, that would completely depend on the head. You don't have to do that with VR or 16v heads, so I'd assume not but I think your best bet is to consult a Bentley manual. That will also give the correct torque settings and also the order in which to tighten them.

Are you going to put the exhaust manni on b4 or after you put the head on?
I suspect you'll put the exhaust manni on 1st.?!??

MUCH easier imo.
In fact when I put the head back on I think I had the inlet manni attached too.

Yea everything that can go on will be going on, an absolute right pain in the preverbial if i dont.

Couple of rules to follow from experience.

Doesn't matter how straight a head measures if it is aluminium skim it. It will be warped.

Make sure that the block is 100% clean

Depending on the engine would dictate whether pastes are required. For example a rover k series requires pastes. However not a single VAG engine does. Check the service manual if not sure.

When torquing up head bolts make sure all the threads of the bolts and any washers are properly lubricated otherwise you are torquing against the thread resistance not giving you a true clamping force.

If the tightening sequence involves tq settings and degrees settings to preload the bolts.
For example take the common VAG 4pot tq settings of 40Nm, 60Nm, 90 degrees, 90 degrees. Before executing the first 90 degrees make sure that each bolt is preloaded to 60Nm again as you'll find by the time you do the outer bolts the inner ones are no longer at 60Nm.

If the tightening sequence includes an tightening measurement in degrees it indicates that the headbolt is a stretch bolt. These are pre loaded using the degree settings in the tightening sequence and require no further tightening. However if using a none stretch bolt like an ARP stud once the engine has gone through the complete heat cycle it is important to check the torque settings whilst the engine is cold.

hth JP

Agree with all that /\

The VR6 engine is one VAG application that benefits from gasket compound where boost is concerned.

No matter what you do to it afterwards, but once the factory seal is broken, they never seem to seal properly again. In fact, even the factory seal tends to seep oil at the water pump end of the block, but it's just a little sweat rather than a leak as such.

My personal feeling is the head clamping arrangements aren't quite good enough at certain points along the head, but not a whole lot you can do about that. The 24V VR6 is massively better though.

For this reason I use Permatex Copper gasket adhesive and swear by it. Providing the block is super clean and the head face resurfaced, the permatex takes care of the last bit of final sealing and it works a treat.

It's even more of a necessity now that the modern thin metal gaskets are common place. They're not tolerant of surface imperfections at all.

Cheers for the heads up with much needed info.

Do i have an aluminium head then or not, G60?

The head has previously been skimmed once and refaced i think once maybe twice, how warped will it be?

G60 head is aluminium, I'm pretty certain.

Kev, where do you get the permatec from? I am gonna use a metal head gasket when I build a block up with my VW cup head.