BMW and Range Rover V8 engine repairs

The V8 engines used in Range Rovers and BMW 5 series, 7 series and X5s produce smooth and reliable power for many years of service. However, some are showing their age with noisy VANOS units, leaky PCV systems and seriously worn timing chain tensioners and guides.

All of these faults add up to cause power losses, increased fuel consumption, mysterious oil leaks and eventually engine failure.

We have invested in the necessary special tools to rectify these problems:-

VANOS Unit Repairs

DSC_0358This is one of the VANOS units on the BMW V8 engine. This photo was taken after replacing the timing chains and guides, and modifying the VANOS units.

VANOS units are a special devices that allow the engine management system to vary the engine’s inlet valve timing, improving the torque output at low speeds and producing good power at higher speeds. However, as the VANOS unit ages, its internal seals begin to fail causing it to make a rattling sound and lose its effectiveness. New units are very expensive (approximately £450 + VAT each!), and there are two in each engine, but a cost effective solution has been devised where the seals can be replaced and the unit modified, providing many more years of reliable service.

PCV System Repairs

The PCV (Positive Crankcase Ventilation) system always suffers from neglect with various side effects such as oil leaks towards the back of the engine, poor quality idle, and sometimes bad smoking from the exhaust.

Repair involves replacing all of the PCV hoses, the PCV valve assembly and the oil separator, many of which are somewhat inaccessible.

Timing Chains, Tensioner and Guides

The main timing chain has a single tensioner which is good for about 100,000 miles, assuming the engine has been well serviced. However, a combination of aging tensioner and stretched timing chain eventually allow too much slack in the chain causing the destruction of the plastic chain guides.


This is a typical sump full of broken chain guide pieces, and you can also see a lot of metallic bits that the chain has started ripping from the interior of the engine.

At this point it will be obvious that something is wrong with the engine and it’s important not to drive the vehicle in this condition – so long as the engine still runs, all should be fine after a repair but please arrange for the car to be delivered to us, not driven, as going bang is very likely and considerably more expensive to repair!

On this particular car, the customer had been given a diagnosis of terminal engine failure, effectively making it a write-off. After a week in our workshop it was restored to rude health and the performance is better now than when it was purchased 3 years ago.

Perfect Running

Doing all of the above repairs at the same time may seem costly but is the most efficient solution, and results in the engine being returned to it’s original condition, virtually silent, smooth and powerful, just as it should be!

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