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Beware the icy roads

31 August 2015

A few years ago we went to Rhodes in the Eastern Cape on a 4×4 trip into the snowy areas around Tiffendell ski resort. The snow was so deep that the farmers had to open the mountain roads with picks and shovels. We were warmly dressed and slept in cosy guesthouses. And every evening we made sure that our vehicles were filled with antifreeze.

During our first night at Rhodes, the temperature dropped sharply and a very chilly breeze started to blow. I parked my 4×4 in a narrow passage next to the guesthouse, where I thought it would be protected from the cold.

Next morning, I switched the ignition on and off a few times to get the diesel engine’s glow plugs to do their work. The engine then started easily enough, but as soon as I pushed down on the accelerator, the engine died. I started it again and allowed it to idle for quite a while before pushing the accelerator pedal, but still the engine would not rev.

After giving it some thought, I realised that the diesel in the pipes must be frozen. Diesel becomes a jelly or slush when it freezes. This means that the pressure of the fuel pump can still suck in and deliver fuel at a slow rate, but as soon as the accelerator is pushed, the thick jelly-like diesel cannot flow fast enough.

I soon discovered that just about everyone in the convoy was struggling with the same problem. After breakfast, we were due to drive up the mountain to Tiffendell. We hoped that the problem would soon disappear as the sun was up, but the vehicles would only move at just above idle speed. Then slowly, one by one, the drivers reported that their engines were returning to normal and the procession could pick up speed.

That night, we parked our vehicles behind a wall to ensure that the cold wind could not blow in under them. This helped, but did not prevent the problem from recurring. We still had to start slowly the following morning.

Back home, I did a lot of research on the issue. Interestingly, the consensus seemed to be that dirty diesel freezes up much more readily. Also, when the engine oil is dirty and diesel has found its way into it, the engine oil can freeze and become like a jelly as well.

I have seen instances where a sump is full of oil, but the oil pump just sucks a hole in the frozen jelly instead of sucking up the oil. The jelly-like oil simply cannot flow normally and cover the hole. So the oil pump pumps air and the engine runs bearings while the sump is actually full of oil.

Antifreeze is just as important. At our altitudes, water often freezes before the temperature dips below zero. When water freezes, it expands, and I have seen welsh plugs pushed out by the ice in the engine and radiators broken by the expanding ice.

So, when it gets cold, make sure that your oil and diesel filters are clean, and that you have topped up with antifreeze. The impact of extreme cold on an engine can be quite catastrophic