I think I like this car. You see, it’s very easy to work on – apart from the horrible location of the spark plugs. That’s good, because I started dismantling the engine without a manual. It must be easy though, because I managed it. I must pay credit to Japanese-spec bolts. After years of working on British and French motors, I half-expect every single bolt to snap. Not Japanese ones though, seemingly the same even when the car is built in the North East of England. There’s a delicious crack, and then the bolt simply comes undone. Even the long bolt that goes into the ‘stat housing, and which looked like it had lived in the sea for 20 years, came out with very little argument. I like that.
No special tools were needed either, with most bolts and nuts 12mm, 14mm or 17mm, the latter just for the exhaust manifold-to-downpipe. Good penetrating oil (I like the No Nonsense stuff from Screwfix, even if it really does pong) helps of course. Before long, I was able to lift the head free and inspect the damage.
I suspected cylinder three was at fault, due to a mouldy spark plug, and I was not wrong. The surprise was that cylinder four had also blown. If anything, this one was even worse, and looked pretty old. The edge of the combustion chamber looked like it had been nibbled away.
Damage such as this is often caused by water leaking in, then getting superheated by combustion, putting too much strain on the aluminium. As well as this, there was, as you can see, a great deal of pitting. This was after I’d deployed some ‘home-brew’ magic too – a sheet of sandpaper under plate glass, to keep it smooth and level. In theory, it would have been sufficient to clean things up. In practice, it did a great job of removing bits of old gasket, but the damage was too severe for that technique to work.
So, I headed off to a machine shop – quite a trek down to Carmarthen to find one recommended by friends. I’m glad I did travel so far, because Adam at Hargreaves Engineering was certainly very knowledgeable, and had no problems with me hanging around to take photos.
After removing the camshaft pulley, Adam loaded the head into the milling machine. A ferocious looking bit spins around a wide circle in this machine, which can be precision-controlled to take very small amounts away. The first rough cut left a crinkle-finish, but allowed Adam to confirm that we would be able to get deep enough to take out some of the low points in the head.
You can certainly see the wide arc the milling machine makes as it passes over the head – or, rather, as the head passes beneath the cutter. Having confirmed that all was ok, Adam could then slow down the table, to give the final clean finish.
There’s not a lot that can be done about the corrosion around the water ports – that’s what you get when you don’t replace your antifreeze regularly. In fact, some of these ports were entirely blocked. Five years is considered a suitable maximum for OAT coolant, but older types should be changed every couple of years – and rarely are.
Next, Adam tested the valve seats. Put simply, if the valve can’t hold a vacuum when one is applied to the relevant port, then it isn’t seating properly, which means combustion pressure is lost, which means efficiency is lost – more fuel, less power.
That’s a duff inlet valve being tested there. It could generate very little vacuum pressure. The inlet on cylinder four, and most of the exhaust valves, also gave a poor reading. This means the valve seats at least need cleaning up with a lap, if not recutting, which means all the valves need to come out. This job had suddenly got a fair bit bigger. All of which means it’s going to be a couple more weeks before I can actually drive my Bluebird. Oh well! See below for a nice shot of it, taken before the dreadful Daimler departed. Yes, it’s gone!
Finally, here’s a video of the first stage of the cylinder head gasket replacement tale.