The Function of the Crankshaft
One of the most precisely engineered and heavy components in your engine is the crankshaft. The task is to transfer the up/down action of the pistons into rotation that eventually is applied to the wheels. Each time the piston goes off firing, the crankshaft stores that energy and converts it to something useful. It is under immense stress and spins thousands of times per minute and carries the entire load of the combustion for all of the cylinders.
The Main Causes of Crankshaft Failure Are:
A broken crankshaft will not give up easily. The first symptoms are usually rattling, banging or ticking noises heard from the engine bottom end, particularly when operating under any load. Any vibration not detected earlier, oil pressure warnings and oil contains metalla at service time are all indications of damaged bearings or damage to crankshaft. When it stalls frequently or fails to start over and over, both the crankshaft and the bearings must be looked at immediately.
Why Crankshafts Fail
Nearly all crankshafts break from lubricating issues. If the oil is starved of oil, it becomes degraded oil or if the oil passages are blocked, the main bearings and rod bearings will overheat and begin to score the crankshaft journals. Too much revving, particularly during cold starts, exacerbates the problem. Manufacturing defects do occur, although very rarely, and in some engine families that have been recalled. Additionally, a timing belt or timing chain failure on interference engines can cause damage to an engine’s crankshaft.
What Replacement Really Means
It’s a huge engine job to replace the crankshaft. The engine typically must be removed from the car. Before removing the crankshaft, the sump, oil pump, timing cover, connecting rods and main bearing caps must be removed. A rebore or re-sleeve might also be required if the cylinder bores are also worn. Very exact torque settings and measurement of bearing clearances are necessary for re-assembly. Researching the crankshaft replacement cost for your specific vehicle before committing helps you set a realistic budget and compare quotes from different garages without getting caught off guard.
The Cost Breakdown Is Shown Below.
The weight of the crankshaft can vary anywhere from 100 pounds to more than a thousand pounds, depending on the engine. Add another hundred to three hundred for main bearings, rod bearings, thrust washers, gaskets and seals. The labour cost is the highest in the bill due to the fact that the job will take between 10 – 20 hours to complete in a professional workshop. In all, the total of an entire crankshaft replacement generally costs anywhere from eight hundred to three thousand pounds. If the damage is not too extensive, reground crankshafts are a more affordable option than new crankshafts.
Reground Versus New
A reground crankshaft will have its journals ground to a smooth, true surface and is used in conjunction with undersize bearings to achieve proper clearances. It can be approximately half the cost of a new unit and, if properly installed, can last as long as the new unit. A cracked, badly bent or worn crankshaft, however, can’t be repaired. It will be measured by your machinist and he or she will advise you honestly.
Conclusion
Failure of the crank means it’s a big problem, but it’s not a fatal issue. Early detection of an issue may mean that bearing replacement is all that is needed. A ground crank means that the cost of the damaged crank is not too high. Have several estimates, demand quality bearings, and have your mechanic torque it all to specification. Your investment will be rewarded with many more miles of engine life.
