I want to run a tap through the holes in a aaz block, however I know nothing about metric tap sizes but there seems to be just a couple of different sizes. Can anyone please tell which one's I'll need to get in order to do them all.
Also - other than the head bolts (as I'll be using studs) which bolts should I be replacing during a re-build and if possible what are the sizes. I'm thinking crank and rod bolts?
Any help appreciated. Thanks
M8X1.25 is probably the most commonly used size
Common opinion is to *not* use a tap for this job, since it will remove metal and weaken the threads..you're after just the dirt.
A different approach is to take one of your old head bolts and grind the end half-way flat... this will scoop up any dirt etc but leave all the metal behind.
I cleaned the threads on my AAZ, but it depends on which bosses you want to clean.
Some are M8 x 1.25mm, others are M10 x 1.5mm. I used a bottoming tap to chase the threads - so long as you use a quality tap, it shouldn't remove any metal. The thread should only chase what was there already - I can't see how it would remove any extra? When I did mine, all I got out was the oily sludge that had taken up residence.
HTH
Make sure your tap is for 2b thread tolerance.
M6-1.0
M8-1.25
M10-1.5
M12-1.75
M14-2.0
That should do most of the entire car...I think the flywheel bolts are a -----at M7-1.0 and the axle stub is M16-1.5 But don't quote me on the last two.
The M6,8, and 10 should do most all of the block for you
Do be careful though, as although all the ones in the block are as listed above, there are quite a few 'Metric fine pitch' nuts and bolts on VWs.
these are typically 10x1.25 and 12x1.25, so if it don't look 'right' it could be a fine pitch.