Removing Engine Sludge and Improving Mini Cooper Performance – Case Study

At GP Motor Works clients often ask us how they can improve their vehicle’s performance especially when their vehicle appears to run very sluggishly.

We had such a case very recently – a client’s Mini Cooper was very sluggish and had a persistent rough idle where the rev counter was hunting a lot. We suggested doing an engine flush to eradicate the sludge in the engine. We also suspected the VANOS (variable camshaft timing) solenoid valves were blocked up with debris.

We decided to use two products to address the two issues, Liqui Moly Engine Flush Plus and Liqui Moly Carb Cleaner.

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Engine Flush Process

One of our technicians first added the Liqui Moly Engine Flush Plus to the existing oil. He then started the engine and allowed the vehicle to run for several minutes to ensure the product evenly mixes thoroughly with the oil and circulates throughout the engine. As this happens the sludge is dissolved into the oil and the deposits are cleaned. He immediately switched the engine off and started to drain the oil completely. The oil was very black and contaminated with engine sludge and carbon deposits.

Our technician then added brand new (specified) engine oil to the Mini Cooper.

Cleaning VANOS Solenoid Valves

The reason we suspected the VANOS solenoid valves were blocked was the evidence of the erratic behaviour of the rev counter.

Now The Mini Cooper R56 engine is fitted with one VANOS solenoid which is mounted to the cylinder head. It basically ensures there is a direct oil flow to the VANOS actuator. This is operated by the engine oil pressure and controlled by the engine control unit (ECM). This is how intake valve timing is managed by advancing or retarding as the revs increase. When this is all operating as it should the engine runs smoothly.

However, when the oil is filled with sludge the opposite happens, the engine performance is adversely affected. There are several reasons why the oil is damaged, perhaps the incorrect oil was used or the oil got very hot. Other causes are when the wrong top-up oil is added or the scheduled oil change is not carried out on time. (refer to this article detailing why the timeous oil change is so critically important to the life of your engine.)

We proceeded to remove the solenoid valves and just as we suspected, the tiny holes in the valve were gunged up with debris and carbon. We used Liqui Moly Carb Cleaner to effectively remove the gunge and re-fitted the valves.

Our client was impressed with the improvement in the vehicle’s performance and in how smoothly the engine was running. Another job well done by the GP Motor Works Team.

A word of caution however, while a good engine flush with a reputable product can help, it is highly advisable that you consult with us before carrying this out. In some cases, it is advisable NOT to use engine flush products, especially in older high-mileage vehicles.

Call us when your engine appears very sluggish so we can give you an expert opinion.