Most modern engines use a variable valve timing system to finely control the timing of the opening and closing of intake and exhaust valves. This ensures the best emissions and efficiency under a variety of conditions.
Usually, this is done with actuators on the front of the camshafts, which are operated by oil pressure.
The oil pressure is metered into the VVT actuator by means of a solenoid-operated valve, usually just called a VVT solenoid. Some engines only use one, while others with multiple camshafts may use one on each cam.
Costs of Variable Valve Timing Solenoid Replacement
Like most vehicle repairs, the cost of VVT solenoid replacement varies per type of vehicle and the quality of the parts being used. These are apart from the difference in terms of the labour rate being applied.
The following are some estimates of the cost of variable valve timing solenoid replacement on a few common vehicles, using £70 an hour as a labour rate:
For a 2007 Nissan with a 3.5-liter engine, the labour time to replace a VVT solenoid is estimated at 0.5 of an hour. A factory solenoid costs about £205, and a Hitachi solenoid costs about £80. The total cost to complete the job would be about £240 using an OE part or about £115 using an aftermarket part.
For a 2009 Subaru Legacy with a 2.5-liter engine, the labour time to replace a VVT solenoid is estimated at 0.6 of an hour, and a non-OE replacement part costs about £63. The total cost to complete the job would be about £105.
For a 2014 Ford Fusion with a 1.5-liter engine, the labour time to replace the VVT solenoid is estimated at 0.5 of an hour. A factory replacement part costs about £25 and a non-factory part costs about £14. The total cost to complete the job would be about £60 using OE parts or about £50 using aftermarket parts.
For a 2014 Dodge Charger with a 3.6-liter engine, the labour time to replace a VVT solenoid is estimated at 0.6 of an hour. A factory replacement part costs about £70, and a non-OE part costs about £50. This makes the variable valve timing repair cost about £110 using OE parts or about £90 using aftermarket parts.
Replacement of Variable Valve Timing Solenoid
Most of the time, the solenoid(s) is located on the front of the engine and is fairly easily accessed. Diagnosis is usually involved at a standard hour of labour, but how that is gone about in this case depends greatly on where the diagnosis is done.
The formal diagnostic procedure on most makes generally requires manufacturer-specific software, which usually requires that it be done at a dealership. At a shop without the required software, a VVT solenoid problem can still be diagnosed, but not always with the same amount of certainty.
The solenoid, in any case, is one of the least expensive and easily replaced parts of the VVT system. Often, the cost of replacement is less than the cost of diagnosis.
Other Related Issues
Most of the time, a VVT solenoid replacement is preceded by a code that points to a timing problem. The PCM looks at the positions of the cam and the crank and determines whether they agree with where they should be according to what valve timing commands it has made.
Usually, the first step in diagnosing a problem is to remove the solenoids and inspect them. They will usually have a screen covering the oil inlet port that can become clogged or obstructed. Sometimes, simply cleaning the screen and the oil feed passage is enough.
One of the simplest things that can cause a timing fault code relates to how the VVT solenoid operates; it metres oil into the VVT actuator. It is important that the oil metering be precise, and that requires that the oil be the correct viscosity.
Old oil tends to thicken up, and the oil that isn’t the correct viscosity will flow at a different rate. Because of this, one of the first steps is to verify that the oil is correct for the vehicle and in good condition.
If this can’t be verified or seems suspect, many times an oil change is done before any further diagnosis. In most cases, if these fail to solve the timing fault code, then all the other possible problems are much more expensive.
Replacing a VVT actuator means removing the timing belt or chain and usually replacing the sprocket assembly on the front of the camshaft. Timing chain wear can also cause a code to set, as a worn chain will lengthen.
This will cause a consistent error in the cam/crank timing correlation. Other problems in the guides, tensioners, or pulleys can also cause the same thing and aren’t always easy to determine without a certain amount of front-engine disassembly.
In practice, it’s common to diagnose by simply checking what can be checked, and then replacing the relatively inexpensive VVT solenoid if nothing else is indicated. This isn’t always the problem, but it is worth a try that can then justify the more expensive diagnosis involved if it doesn’t correct the issue.