Skoda Rally Blog

… is how today was supposed to be.  In essence, remove the old manifold and cylinder head, check the height of the pistons above the liners (which should be 0.6-0.7mm), and then put the new head on, put the manifold on, make all the right adjustments and then fire it up.  Easy.

So, I got started fairly early, and removed the old inlet manifold and the exhaust, and then it was time for the head to come off.  Basically, undo bolts, easy enough.  I’d drained the water out of the engine yesterday, so it was all nice and dry, and all went according to plan.  Once the bolts were undone, the pressure of the cam on the two open valves in the engine meant the head was already pulled away from the block, and nice and easy to lift off.  I took it off and put it in the garage.  And noticed something unusual – usually the head gasket stays with the block, but this time it was stuck to the head.  Fair enough.

Then I went back to the engine, and thought I must have been seeing things – the gasket wasn’t on the head, it was on the block.  Had another look at the head.  That had a gasket too.  There were two gaskets fitted to the engine.  Alarm bells sounded.  Those of you who are regular readers will know this engine was bought early in the year (when it was snowing), and installed with the help of a friend ready for the Sunseeker, and wasn’t run that much – just to check that it fired up – as it was time for mapping when I became incapacitated.  So this engine hadn’t done a lot of running.  And it had never really run right, it seemed a bit lumpy.  And I guess I was seeing why now.  I went back to look at the head, and noticed something else which wasn’t right – the edges of the inlet valves were shiny, which made it look like there had been valve/piston contact.

Valves should not have a shiny bit on them!

So I then took a look at the pistons to check them.  Same story there – shiny bits on them, where they had clearly been hitting the valves.

Pistons shouldn't have shiny bits either!

So, this wasn’t looking good at all.  Time for some measurements – the head builder told me that ideally there should be a 0.8mm clearance between piston and cylinder head, and a compressed gasket it 1.5mm.  So I’m looking for the pistons to be 0.6-0.7mm above the liners.  I got the verniers out, and measured…. 1.2mm.  Clearly not going to work either.  I then took a closer look at the pistons, and they seemed to be very loose in the bores.  Plus I had no idea what the problem was with the camshaft – it could be the timing was a long way out leading to the interference between the valves and pistons.  In short, looks like I got a complete pup.  And more to the point, time for a different bottom end – there was NO WAY I’d risk my new head (which cost over £1000) on this.  Fortunately, I have a couple spare!

From the shed, up came the engine that did Rally GB 2008 – this was a good engine which ran well but was limited by the head and inlet manifold, so I got the head off and measured the piston protrusion – spot on at 0.6mm.  Then did a dummy build with an old gasket (handily I have a few about) and the new head, to check valve to piston clearances with some plasticene on each piston, plus also getting the valves set up and checked.  Only takes a second to write the sentence, takes about an hour to do.  But all was good – had a 0.92mm clearance to the head, which isn’t exactly right (being 0.12mm wider than spec), but is good enough, I think.  Then did the real build with a new TEMAC gasket, torqued everything up, and then transferred all the studs into the new head (which again, quick to say, a while to do).  The engine was pretty much ready to go in, but of course next the other one had to come out.  I’ve obviously done this a fair few times, so it’s fairly straightforward, other than the fact that I have a sling that I use that is usually attached to the head… which was missing, so getting the engine out wasn’t that smooth.

Split the engine and box, and then fitted it to the new engine.  I did this with the engine on a stand (I made a few up for storage purposes), which made is SO much simpler than before – usually this is a really annoying process, but with the engine held firm and square, it was dead easy.  And as if by magic, Kevin appeared – up to this point, Mum had been helping with the two-man bits, so was glad to be relieved of duty.  With the engine now in place, and the sling set properly, getting the engine back in place was dead easy – everything lined up easily, and it bolted up without any drama.

At this point I needed to stop because I have  my bike up for sale (which is how I’m paying for the cylinder head or the entry to Rally GB, depending on which way you look at it), so I wanted to tidy up before he came over.  Thankfully that paid off, so I have the money for the entry!

Tomorrow, everything else will be put back on, and hopefully in a position to fire up – the silicon hoses for the air intake arrived this morning, so it seems everything is in place, albeit with a lot more work than expected.  Here’s hoping it pays off.