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This month we are looking at a Series Land Rover fault diagnosis exercise. Symptoms of the actual problem will be described. You are encouraged to follow your own path to a diagnosis as to what may be causing the problem at the same time as following through the diagnosis strategy presented.
A clattery sound from the top of the engine suggests that the valve clearances may not all be correct. This would cause lack of engine power as some valves would not be opening and closing at exactly the correct time. So the first job is to remove the rocker cover and, using the rule of 9 check the valve clearances (valve 1 fully open check valve clearance on valve 8 etc). Result is that two valves have clearance of 0.012thou instead of 0.010thou. But this is not much error and only on two valves. An engine test confirms that the clattery sound has gone but the engine still lacks power on a road test.
So, to test if the problem is ongoing, a new spark plug is put into No1 cylinder and the Land Rover is road tested again. Result is a brief improvement in performance but then back to serious loss of power. On removing the new spark plug a drop of fresh oil is seen on the plug. At this point, shining a torchlight into No1 cylinder shows black oil deposits on the top of the cylinder head. So oil is entering
No1 cylinder somehow.
On examining the valve stem oil seals they are found not to be damaged but may be slightly hardened. New seals are fitted.
So we may be looking at multiple causes for the power loss. We need to check the piston rings and bore. Although compression seems good, there may be a problem with the oil scraper ring, allowing oil to get past it and into the cylinder via the gaps in the compression rings.
At the time of needing to post this online piston rings at +060thou are still being sourced, so this exercise will have to be updated later in the month. Watch this space.
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