So the mighty Audi came to me with a cold start problem.
Having spent a long time around EFI engines, particularly the Cossie, I knew there was a few basics that needed to be checked out first.
- Fuel pump -> OK
- Crank position sensor -> replaced -> OK
- Coolant temperature sensor -> replaced -> OK
- Phase sensor -> OK
- Spark plugs -> replaced -> OK
- Coil packs -> OK
The cold start problem manifested itself as and engine that would crank but not fire after it had been left for a few hours, or would misfire and run on 3 until something had cleared. Eventually
In the meantime the water pump failed, either due to the underlying problem, or separately, it’s not clear. The pump did appear to have received some damage to the impeller though, which was odd. Replacing that was a mission in itself too!
Back on topic, the gasket failed in the weirdest way – Cylinders 2 and 3 turned out to be blowing out of the exhaust side of the gasket and into the coolant jackets, and then drawing coolant into the bores after the engine was shut down. This left an engine that wouldn’t start when it had been left for several hours without first depressurising the coolant system. When the engine finally overheated and the head was removed a few weeks later, the cause was found, along with two bores full of coolant.
After mopping out the coolant and re-oiling the bores, the head was taken to the folks at Headline MK in Woburn Sands, near Milton Keynes to be rebuilt and cleaned up. They’ve done a bangup job for a perfectly resonable price, including:
- minor repair to a water jacket
- New valve stem seals
- Resurfaced valves
- reset cam timing
Now comes the semi-daunting task of putting it all back together. Hoping all the screws and nuts I removed go back where they came from!