How to cure a valve tap/how to change your oil

So the other week my C240 developed a little valve tap when it was cold. Like most modern engines the valve lifters on the car are operated hydraulically. They begin to tap when the oil pressure is wrong for them as too much oil or an oil that is too heavy means that the lifter cannot properly travel.

Since oil thins as it gets hot and the tap went away once the car was hot I’m going to assume that the oil is too thick. Both Halfords and Euro Car Parts suggest a 10w40 which is a very thick oil when cold. It might be fine for the car in the summer but in the winter it is far too thick!

The owners manual suggests a range of oils with 10w40 being used on hotter climates and 5w30 and 0w30 being used in more moderate and colder climates. I thought I would get some 0w30 as it is thinner it will help clear any muck out of areas that the 10w40 might have not so easily gotten into and then I will change back to 5w30 in the summer. The 0w30 I went for was Castrol Edge from Amazon: Castrol EDGE Engine Oil 0W-30, 4L


I also picked up a couple of additives to put in with the new oil The first is WYNNS Hydraulic Valve Lifter Treatment  which is designed to release sticking valve lifters and the second is Moly 63399325 Engine Protector with Molybdenum which just offers a little more protection atop of the standard oil
Some people don’t believe additives do anything. A lot of people seem to buy them as a cheap miracle cure for a problem without addressing the underlying issue. Injector cleaner for instance is only going to work for a little while if you are using a low octane cheap supermarket fuel and valve lifter treatment is only going to work for a short while if you are using the incorrect oil.

Anyway onto getting the old stuff out!

First thing to do is to jack your car up and get it one axle stands. Once you have done that you are going to need to locate the sump plug.

The oil sump is kind of like a pan that sits under your engine and is where the oil is kept. It is literally the first thing you will see as you look at the bottom of your engine. What we are looking for is the sump plug. The sump plug is basically a bolt that when removed allows the oil to drain out.


Before you undo this you’ll want something to catch the old oil as it falls so you don’t make a mess. An old bowl does the job nicely but Halfords sell these cool jerry-can like things that you can drain your oil into. They are only about £6 if memory serves and are sealable so you can get rid of your old oil easily and safely!

Position it a little way back as the oil likes to come out pretty quickly haha!


And undo the plug!


Now the old oil is draining it’s a good idea to have a look at the sump plug to clear the threads of any debris and check for damage. A stuck some plug makes doing this job a little more complex.


Now the old oil is out it’s time to change the oil filter. Some cars will have the filter underneath the engine and some will have it above, so it is dependant on your car. With most cars you change not only the paper filter but the whole housing too, it sort of screws off as one big unit. With this Mercedes however the housing stays in place; you just unscrew the top and replace the paper bit of the filter. At least it is right at the front left though so easy to get to! You see the big cylinder?


With that replaced it’s time to add the new oil! On top of your engine block you will find a cap marked with oil. On mine it’s conveniently behind the oil filter. Most cars thankfully have it in a sensible location! Simply open it up and pour the new oil in!


This Mercedes has a capacity of 8 litres. So I added a litre, the the additives and then the rest of the first bottle of oil. I then checked the dipstick to see how full it was (It was reading empty at 4 litres!) The second bottle I only added half a litre at a time and kept checking the dipstick until it read about three quarters full. It’s important to only top up with a half litre at a time as overfilling the engine can do damage.

Job done!! Now take it for a little drive to get the oil settled in! It can take a minute for a valve tap to go away but this one was gone instantly! So if you do have a little valve tap replacing your oil and filter is a super easy and fairly cheap way of hopefully fixing it!

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Twitter: @Garage_RFrancis
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