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Defective valve stem seal: symptoms, changes and costs!

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Recently updated on September 30, 2023 at 10:59 am

Defective valve stem seal: symptoms, changes and costs!

[Update: 30.09.2023] This post was updatedto take more recent information into account. The valve stem seals (or valve stem seals) are located on the individual valves and take over in the engine the sealing of the valve control opposite the intake port. But what are the indications of defective valve stem seals? Due to signs of wear due to age and high (including thermal) load, valve stem seals can become brittle, preventing them from sealing properly. This results in the following two main symptoms: Increased oil consumption over a short period of time and strong fumes / clouds of smoke escaping from the exhaust! 

engine damage is imminent

Of course, behind the symptoms but also other defects such as damage to the crankcase ventilation, the turbocharger or a worn one Cylinder head gasket put. A clear diagnosis can usually only be made after the cylinder head has been removed.

Defective valve stem seal: symptoms, changes and costs!

Attention: In the worst case, excessive oil consumption can lead to one engine failure come with very high consequential costs. That's why you should go to the workshop at the first sign of excessive oil consumption. the Amount of the oil consumption of an engine per 1.000 km is disputed. The value also depends on the manufacturer and the design of the engine. In principle, however, one can assume that in modern vehicles everything over 0,5 liters per 1.000 km is too much and requires verification.

Repair or replace valve stem seals?

Depending on the vehicle design, the valve stem seal can sometimes be replaced high effort and costs go hand in hand and should discord be carried out by a specialist workshop with the appropriate expertise and special tools. Because assembly errors can quickly cause engine damage. The number of valve stem seals corresponds to the number of valves and depends on the respective engine. For example, on a 3,0 liter 24V engine there are 24 valves and therefore 24 valve stem seals to change. The exact replacement process varies depending on the vehicle model. After taking the Engine cover takes place, if available, the expansion of ignition coils and ignition cable.

This is followed by the removal from the valve cover and the dismantling of Timing belts and the timing chain. After that, the expansion of the attachments is like Exhaust and intake manifold your turn and the Cylinder head disassembly with the associated expansion of camshafts follows. The valves can now be accessed and the worn valve stem seals can be replaced using a special tool. As part of the change, there should always be a change - if available - of the toothed belt including water pump and the corresponding tensioning and deflection pulleys. In addition, replacing the Cylinder head gasket, Cylinder head bolts and the valve cover gasket are required for operation.

Cost of changing the valve stem seals!

The total cost of an exchange can vary greatly and is largely dependent on the vehicle design as the labour costs make up most of the total cost. The material for a new set of valve stem seals costs only 5 to 50 euros. Well-known spare parts manufacturers are Elring, Victor Reinz and Febi Bilstein. Depending on the vehicle model, between 3 and up to 14 (!) hours of work are required to change the valve stem seals. At an hourly rate of 100 euros, labor costs fall by 300 to 1.400 euros at. Material costs for the new valve cover gasket must also be taken into account. The new cylinder head gasket and (if no timing chain is installed) required toothed belt set, possibly with a water pump, can also be expensive. There is also a renewal of the engine oil. Exactly how much each material costs varies greatly. Overall, however, with total costs between approx 350 and 2.500 euros expected.

Defective valve stem seal: symptoms, changes and costs!

Defective valve stem seal – summary:

The Valve stem seals are an essential part of the engine that ensures proper lubrication of the valves and prevents excessive oil flow. If these are faulty, it can lead to a number of problems.

Signs of a defect

You can recognize defective valve stem seals by looking at them extremely high oil consumption, blue exhaust fumes at cold start or excessive exhaust smoke when changing gears. Also Combustion gases in the crankcase and air filter can indicate the problem.

How valve stem seals work and what they mean

Valve stem seals prevent excessive Oil flow from the valve train into the combustion chamber and ensure sufficient Lubrication of the valve body. This can occur due to wear or damage to the valve stem seal motor oil get into the intake or exhaust tract, which leads to increased oil consumption.

Cost of replacing valve stem seals

The cost of replacing valve stem seals varies Make, model, engine and selected workshop and amount to approximately 330 € to 2000 €. The exchange of the Intake and exhaust valves for a 4-cylinder petrol engine is between €400 and €700.

Position of the valve stem seal in the engine

The Valve stem seal is located on the individual valves and is intended to prevent oil from spilling over the valves valve stem enters the combustion chamber. A correct fit and an intact seal are essential to ensure the efficient functioning of the engine.

Replacing the valve cover gasket

Changing the valve cover gasket can be between 30 minutes and 3 hours time, depending on the additional units to be removed and the cleaning time of the sealing surfaces. The material costs are manageable, and the seal usually costs between 15 and 50 euros. The work required is around an hour, but can increase to up to two hours if the valve cover is difficult to access.

Driving with a defective valve cover gasket

A defective valve cover gasket can lead to... increased oil consumption and thus to Environmental pollution lead. It is advisable to have the seal changed quickly and inexpensively to avoid higher costs.

Difference between valve cover gasket and cylinder head gasket

While the valve cover gasket seals the area between the valve cover and the cylinder head Cylinder head gasket for the seal between the cylinder head and the engine block. It has to withstand combustion energy and is therefore made of metal embedded in the plastic.

Renewal of the valve stem seals

Aggressive chemicals, high temperatures and mechanical stress can wear the valve stem seals and cause the material to fatigue. A workshop must then Change valve stem sealsto ensure the correct functioning and efficiency of the engine.

The following note is essential: For safety reasons, tuningblog recommends all repair, inspection and maintenance work exclusively to be carried out in a specialist workshop! Although our information is summarized to the best of our knowledge and belief, we cannot assume any liability for the content. All information is therefore "without guarantee".

Of course, that wasn't the end of it!

In this tuning blog category there are guides and instructions on common defects/repairs on the vehicle as well as on installing accessories/tuning parts. Our articles explain common defects and the corresponding repairs in a simple manner and also explain how the first signs of a defect become apparent.

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Defective valve stem seal: symptoms, changes and costs!

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About Thomas Wachsmuth

Thomas Wachsmuth - He has been an integral part of tuningblog.eu since 2013. His passion for cars is so intense that he invests every available penny in them. While he dreams of a BMW E31 850CSI and a Hennessey 6x6 Ford F-150, he currently drives a rather inconspicuous BMW 540i (G31/LCI). His collection of books, magazines and brochures on the subject of car tuning has now reached such proportions that he himself has become a walking reference work for the tuning scene.  More about Thomas

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