Valves belong to the most important components of a combustion engine. They regulate the inlet and outlet of the air-fuel mix and seal the engine during combustion. All valves are constantly in motion and as mechanical parts subject to gradual wear. In this guide, we suggest you on how to check the condition of the valves as well as how to adjust them. A manual for replacement of worn engine valves is added below!
Checking the engine valves
Basically, all engine valves in almost all cars and model series are built to last the entire life span of the car. Nevertheless, untimely wear can occur due to intensive use or defects and therefore the condition of the valves should be checked at regular intervals. Particularly their tightness (sealing quality) should be analysed as otherwise the combustion is not optimal. Initially, this leads to a higher oil consumption or performance deterioration of the car. In the worst case, the heat and the fire of the combustion chambers affect other parts in the engine.
For laymen, valve repair is rather difficult. Small errors have considerable impact on the engine function and the combustion. If you lack the required experience, restrict yourself to general inspection on general damage such as ruptures or very obvious wear. Very often, a suspicion such as unusual noises or the car failing to attain its usual performance precedes this inspection. A more detailed check is performed by garages on occasions of an extensive inspection.
Adjusting engine valves and valve clearance
More important for a clean combustion and a smooth running of the engine is the regular adjustment of the valves with their valve clearance. This also applies to valves which are physically intact and not yet worn. For the adjustment is it important to know how the valves are opened and closed by the camshaft and which processes are at work here.
It is not possible to give a general value for the optimal clearance between valve and its valve rocker. In most models, half a millimetre should not be exceeded. Guide values can be found in the car manual or must be checked with the manufacturer. The actual adjustment is done with a bolt on the valve rocker on the side of the camshaft with a corresponding nut. For an exact adjustment a feeler gauge is the proper equipment, which is nowadays available with laser technology enabling an even more precise measurement.
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Cleaning the engine valves
Deposit on the valves or a gradual corrosion cannot be avoided even with proper car maintenance. Occasional cleaning of the valves is necessary for which they must be removed from the engine. The specialised dealer has a special spray cleaner for valves, removing a large part of the superficial dirt. Other car fans rely on household products such as oven cleaners, which show a similar result.
For persistent dirt or adequate removal of rust, the careful use of steel brushes and similar products is recommended. Alternatively, the valves can be soaked overnight in a bath for removal of caked dirt. No experiments are allowed with these hour-long solutions and you should exclusively rely on professional products from the specialised dealer.
Defining engine valve noises
Noises such as rattling or a scratching sound coming from the engine can indicate problems with the valves. A too large or to small valve clearance can be acoustically observed and corrected by adjustment of the valve rockers. All other valve repair is done by their replacement, although you can try thorough cleaning first. Contrary to the valve clearance, a lot of wear does not make itself heard, but is betrayed by a deteriorating engine performance or a higher oil consumption. However, these can be the result of other engine trouble as well and therefore an exact diagnosis of the malfunction and its causes is necessary.
Engine valves replacement – a DIY manual
Installing and de-installing valves doesn’t require a professional hand, although some dexterity is necessary. We recommend visiting a garage nevertheless, as the replacement occurs right at the engine and therefore right at the heart of the car. For valve adjustment as well, dexterity and experience are very important, even though a DIY job might not appear difficult at first sight.
INFORMATION ON ENGINE VALVE REPLACEMENT
|When is it necessary?
– Obvious extensive damage
– Persistent noises from the engine
– Extremely high oil consumption
– Engine performance deterioration
|What do I need?
– An adequate set of valves per cylinder
– A well-sorted tool box
|How expensive will it be?
– Depending on model £6 – £13 per valve seat
|Advantages of DIY replacement
– Low cost
– Quick execution in a few moves
– Simple accessibility
|Advantages of replacement in a garage
– Professional execution
– Professional valve clearance adjustment
– Possible necessary replacement of hidden valves
Prior to replacement the exact location of the wear must be determined and if replacement of all valves is really necessary. Often, only the valve seats not sufficiently sealing the inlet and outlet valves to the engine are affected. In all cases a complete replacement of the affected components on all similar valves of the car is recommended, which means that on every cylinder the same steps must be taken.
Step-by-step replacement of engine valves and valve seats
The replacement of whole engine valves or separate valve seats takes place in several steps. First, the bonnet of a cooled engine must be opened to be allowed a direct view of the separate cylinders. Then the cylinder head gasket must be disassembled to open the way to the valves. These must be removed from their screw thread with the proper tools. Now a complete overview of their condition and possible wear is possible. Every cylinder generally has two inlet and two outlet valves. Many engines have hidden valves, which are not directly accessible by disassembly of the cylinder head gasket. This could be a task for the garage. If it comes to a complete replacement of the valves, the valve springs and the gaskets of the valve stem must be replaced as well. This generates higher costs, but provides the driver with the certainty, that he can rely on completely new valves for daily engine use.
Further tips for engine valves replacement
Although most drivers do not need to worry about the valves during the entire life span of their car, sometimes defects and wear make an untimely replacement necessary. Before you make a lot of costs, you need to know the exact cause – especially in case of engine problems, the cause of defects and a lower engine performance can lie elsewhere. A professional replacement of all valves at several hundreds of pounds is not really cheap, but gives you the certainty of a professional repair. There is no denying this if you wish to enjoy your car for a long period of time.
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