Never trust a boil

Subsequent to my article “I’ve Got Boils” and having thought that episode was history, have a read of this one.

During the morning of Christmas Eve I took the 1932 20/25 Hooper saloon to fill it up with fuel. As I was aligning the car to the pumps, I noticed a cloud of white stuff emitting from the exhaust pipe. I woman behind was hardly visible and beginning to choke. This was distinctly embarrassing for me. Having refuelled, I drove the car off the forecourt and with the engine running examined the nature of the cloud. First impressions were that the carburettor had become detuned or that some debris had become lodged therein, thereby rendering the mixture very, very rich indeed.

I drove the car home, giving the accelerator some intermittent grief in an attempt to clear the problem, but in vain. Once home, my son and I fiddled with the starting carburettor, fast and slow idle screws with no effect and a closer olfactory investigation of the exhaust gases suggested that there were no excessive amounts of unburned fuel leaving the engine. Removal of the spark pugs revealed that No. 5 and 6 plugs were wet. Steam was the tentative conclusion. A call to John Eastwood left me with a series of possibilities, most of which sent me into a spiral of anxiety and depression. A cracked cylinder head ? “Oh no. The head was a new one just 5 years ago. The cost of another one! My God!”

John called back about half an hour later to say he was on his way to provide assistance. In the meantime I had to nip out to gather some provisions in advance of our departure to France on Boxing Day (Dec 26th). By the time I got back to the house, John was finishing off his investigations which had taken about 20 minutes. The carburettor was fine, but on removing the spark plugs and engaging the starter motor, he witnessed spurts of water droplets and some steam spurting up from cylinders 5 and 6. A blown cylinder head gasket was the least offensive suggestion and the most damaging to my cerebral hemispheres was the prospect of either a cracked head or block. None of this helped my desire for an arranged, pleasant Christmas Eve dinner with six friends around our dining table.

Our twelve days in France failed to eradicate the problem from my mind. It was confronting me many times each day and during the nights. As soon as we had returned home, the time consuming process of removing the aluminium head began. The head gasket looked as though it had been on holiday in the Afghanistan war zone; a gap between cylinders 5 and 6 had developed to the width of a finger. Where all the copper had vanished to is anyone’s guess, but the gap was sufficient to allow circulating water from the block to pass straight into the two cylinders in question. Other than giving me a pair of steam cleaned piston tops and valve areas and some slight pitting of the aluminium, there were no signs of any other damage. The drained off coolant was uncontaminated but the engine oil was a perfect emulsion and as a consequence its volume was far greater than the assumed 1.25 imperial gallons.

The new gasket was replaced and everything reinstalled. Incidentally, a number of new exhaust manifold studs were required. The nuts on them were very difficult to remove and for half of them nut removal resulted in the stud unscrewing from the head. The bench vice, penetrating oil and blow torch failed to ease the problem. I now know that a preventative measure here is always to used copper grease on the nut end of the studs, something the ex-Coldwell Engineering man who did the engine rebuild some five years ago had clearly failed to do. The nuts were so ‘welded’ to their studs that for most of them my attempts to free them using a spanner resulted in them shearing.

Fresh SAE 30 engine oil was introduced, as was the coolant. With everything now in place, the engine was fired up. Even without tappet adjustment, the sound was pleasant to the ear. However, once the oil had reached the rocker and then the tappets, my heart sank. The emulsion was still there. Was water still getting into the oil pathways? If so, the head would have to come off again. A call to John Eastwood was necessary. He was somewhat baffled and he suggested a compression test on all cylinders. Within 10 minutes this was done and pressures were all identical and holding. John suggested that with so much water entering the crankcase it might take quite some time and at least one more oil replacement to rid the engine of the contamination. The purchase of a gallon of flushing oil and some cheaper 20/50 oil was essential. Following three such flushings with engine running up to hot conditions between each of them, the problem was rectified. It is amazing how long it took, but considering the physical reaction between the oil and the water and the subsequent adhesion of the emulsion to the linings of the various cavities the oil passes through, it is not really surprising and running the engine for twenty minutes or so following each oil flushing not only breaks up the residues but also helps to remove some of the water in the oil by evaporation into the exhaust gases.

As a matter of interest, caution and warning, the guy who did the engine rebuild, long gone from Chesterfield and now working from a house near Hull (he doesn’t want me to know his address!), was not always as thorough as he would like his clients to believe. Since the engine rebuild, there has always been a tappet-like and very annoying tick on the manifold side of the engine. My own stereoscopic hearing facility always drew my eye to the middle of the manifolds, but this location may not have been the sound’s origin. Perhaps it was being transmitted from the timing chamber at the front. As part of another major job on the car, he included as part of his charges a removal of the radiator and an investigation within the timing gears. He failed to locate anything. He even told me that perhaps I needed a replacement timing gear mechanism from a dismantled 20/25. Several investigations of the tappet clearances and re-settings since then resulted in nil change. Having now had the head off for the first time since his rebuilding of the engine, the tick has disappeared. As soon as I had removed the exhaust manifold, the tick-generating problem was exposed. He had failed to install the gasket between the descending leg of the exhaust manifold where it meets the inlet manifold! The soot on the surface of the inlet manifold at this point told all and explained the problem. I have installed the missing gasket and the tick is now history.