Head rebuild.

So someone on here msut have undertaken this.
many specialist tools?
Am I better of farming this sort of thing out to a pro?
I'm sure all the pro's will say yes.

To be fair, it isn't that bad a job to do. I rebuilt my valver head but left the guides as I thought it required a specialist (I've since been told of a good method to DIY that part of the job).

Tools wise, you'll need a valve spring compressor, valve lapping tool and paste and small fingers. The only other thing you need is a means to remove and replace the guides, but I'll come to that.

This is the method I used...

1) Remove cams, remembering the order and location of each cam cap.

2) Remove Hydraulic tappets. This can be a bit tricky as they will be covered in oil and they kind of stick (hydraulic action of the oil)..

3) Compress the valve spring with compressor, try and get the collets off, they should stay stick to the top of the valve stem because of the oil again. release the compressor and the valve will be released. It's not entirely necessary, as you'll be lapping the valves in, but stick the valves through a peice of card so that you keep the same order for them to go back in. Repeat for all the valves.

4) Now this is the bit I didn't do, but have read this is a good method...
a) Find a suitable 6 inch bolt and turn down an inch or so of the length of it so that it fits inside the valve guide. then turn the rest of the length down so that its wider than the internal diameter of the guide, but narrower than the external diameter, and leave a 90% shoulder where the change in diameter is.
b) Get a heat gun and stick the end of it in the port of the guide that you are going to remove, and warm up the casting.
c) You should then be able to use the bolt to tap out the guide quite easily. The guides should have a shoulder on them to stop them from going in too far. Obviously you need to determine which end the shoulder is on so that you don't stand there for 30 mins trying to extract them from the wrong end
d) Meanwhile stick the new guides in some liquid nitrogen. Admittedly most people don't have access to liquid nitrogen so in the freezer overnight will suffice
e) Again heat up the casting as before and then using the extra cold guides you should be able to tap the new guides in, from the opposite end to their removal, and as far as they will go based on the shoulder.
f) Repeat for all the guides.

5) Next you need to get you valve and lap it back into the valve seat. I used a special drill attachment that oscillates to provide the lapping mechanism and basically lapped until there were no pits on the seat, using course then fine paste.

6) Now here comes the first fiddly bit. You need to push the valve stem seals onto the top of the guides. Getting them seated right is tricky because the casting is kind of in the way, I then used a socket to push them on, although I'm not convinced that is the best way, as you don't want to damage the seal. Them push the valve back in and be careful not to dislodge the new seal. Repeat for all the valves

7) Now here comes the next fiddly bit, where small hands/fingers are definitely an advantage. Repalce the valve and spring and spring retainer, compress with the valve compressor and get your collets back on the end of the valves. Definitely easier said than done. I found a little bit of oil helped with them 'sticking' to the end of the valve stem. Repeat for all the valves

8) Finally stick the tappets back in and the cams, paying attention to the correct order of the cam caps.

I hope that isn't too much mumbling, and I'm sure someone will come along and correct me, if I've said something not quite clear or indeed the correct method....

Thanks stu,that was quick.
Very Impressive.

yeah I have removed valves,tappets collets n stuff b4 but I have never attempted valve stem seals.
I'm game for giving it a go though.Something to do over the festive period asside from gaining half a stone.

I have a little pen style mageny that i use to sort of position the collet in place while I decompress the spring.Very fiddly,takes a bit of practice each time you do it.
Cheers buddy.

So do the valve seals a skim amd a clean and I should be good to go!?!?

Sort of what Mr beige said. Heating the head and freezing the guides is a good tip. Tool wise I'll take series of pics at one point if people are interested.

But as a rule of thumb the driver you use to refit new guides should have an internal support all the way into the guide to stop it collapsing and it is an idea to ream to spec for oil clearancing otherwise you can end up with sticky valves.

Refitting stem seals you use a pilot dow the guide that aligns the seal perfectly to the guide which has a cup fitted over the pilot to drive the seal home with a couple of light taps of a hammer. This way you avoid any distortion.

Refitting the valve locks use a bit of LM grease smeared into the grooves of the valve stem before refitting them into the head. Then use a very light magnetised tip of a thin flathead screwdriver to locate the locks. The grease will hold them in place whilst you position the second and release the clamping tool.

As for lapping the valves in a lot of the time especially on valvers you will need to recut the seats before lapping as the guides 90% of the time go in pissed.

If you look at the Golf + tech sections from the beginning of 2008 (poss Jan or Feb issue) I wrote a 3 page article rebuilding a VR6 head with all the tools and techniques shown.

JNLRacing wrote:Sort of what Mr beige said. Heating the head and freezing the guides is a good tip. Tool wise I'll take series of pics at one point if people are interested.

But as a rule of thumb the driver you use to refit new guides should have an internal support all the way into the guide to stop it collapsing and it is an idea to ream to spec for oil clearancing otherwise you can end up with sticky valves.

Refitting stem seals you use a pilot dow the guide that aligns the seal perfectly to the guide which has a cup fitted over the pilot to drive the seal home with a couple of light taps of a hammer. This way you avoid any distortion.

Refitting the valve locks use a bit of LM grease smeared into the grooves of the valve stem before refitting them into the head. Then use a very light magnetised tip of a thin flathead screwdriver to locate the locks. The grease will hold them in place whilst you position the second and release the clamping tool.

As for lapping the valves in a lot of the time especially on valvers you will need to recut the seats before lapping as the guides 90% of the time go in pissed.

If you look at the Golf + tech sections from the beginning of 2008 (poss Jan or Feb issue) I wrote a 3 page article rebuilding a VR6 head with all the tools and techniques shown.

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pics would be great.
I don't have any back issues of golf + i'm afraid.
I'm sure others would be interested too

top tip for removing tappets is either a magnet pen thingy or the the wooden stick with the suction vup on it that you use to cut the valves back in with

I would also recommend purchasing one of those generic automotive multi peice vacuum / pressure test kits. They're not expensive. Some of them can check for water, intake/exhaust and oil way sealing too, i.e. crack testing without expensive x ray analysis.

You can create a vacuum across the head ports to check how well your valves are sealing and removes the guesswork. You just put a plunger with a tube attached across one of the ports, suck all the air out and see how well the valve holds the vacuum. The posh kits have gauges etc too. If the valve holds vacuum well, then you know you've done a good job and don't need to faff around with engineering blue.