BMW M323i Very Noisy N52 Engine
This BMW M323i was brought into GP Motor Works by a client with the typical N52 engine with frustrating ticking noise problem. The car also had a oil leaks.
As expected, our computer diagnosis pointed to the failure of the hydraulic valve lifters.
Purpose of The Hydraulic Lifters
Simply put, the hydraulic lifters take up the clearance between the valves and rockers.
In the old days, cars had tappets which were adjustable. Their function was to have the correct clearance when there was a change in temperature between the camshaft, valves and rockers. The problem was it wasn’t easy to set the tappets. If they were too tight it would cause excessive wear and too loose would make the engine noisy.
Hence, the hydraulic lifters were invented. They are self-adjusting and take up the change in clearance automatically.
How Do Hydraulic Lifters Work?
Effectively, the whole process begins with the oil pump. It pumps pressurised oil through the engine. The oil travels up through the galleries, into the head and finally, through small holes, into the hydraulic lifters.
The lifters consist of an outer shell which contains an internal spring loaded plunger. So as the engine runs, oil fills the outer shell and the spring and pressure from the oil pushes the plunger to extend the lifter. The camshaft then pushes the lifter down and so the process repeats itself.
The combination of the plunger and spring work in tandem to ensure the clearance within the valve train is constant. This is key to minimise the engine noise and to ensure quieter driving. The hydraulic filter also prolongs the engine’s lifespan by reducing excessive wear and tear.
What Causes A Noisy Lifter?
There are many reasons why lifters become noisy:
- Not enough oil pressure
- Faulty oil pump
- Blocked gallery
- Dirty oil and filter
- Oil sludge build up
- Use of incorrect oil
- Worn camshaft, rockers or valves
It is very important to change the complete set of lifters when doing repairs. Also, if any engineering work is carried out on the head the lifters should be changed.
Call us immediately if you start hearing a lot more noise from your engine. The earlier you take action the less damage will potentially be caused.