Valve train problems It can cause all kinds of engine performance problems, including:
- High oil consumption
- Blue smoke
- Cylinder head noises
- Ignition failures
Valve train problems can appear when, for example:
- allows the oil level to drop;
- forget about changing the oil at regular intervals;
- operate the engine when it is overheated;
- or go long periods without maintenance or without troubleshooting the engine.
But valve train problems can occur even if you service your engine on time and make necessary repairs, especially if your engine has a lot of mileage. Whatever the reason, this guide helps you diagnose the most common valve train problems and their possible sources. Diagnose the problem sooner rather than later to avoid costly repairs.
If you are concerned about engine noise and are not sure where it is coming from, check out this article on diagnosing engine noise before you begin troubleshooting valve train components. It will help you identify the source of the noise, anywhere in the engine.
To make it easier, the following sections are broken down into symptoms that can be caused by different types of valve train problems. Take a look at the index below. If one or more of these symptoms seem similar to the one you are facing, go to that section. Reading additional sections will give you more ideas on the types of problems that can arise and will help you with your repair project.
However, before we begin, keep in mind that while we focus on valve train issues here, none of these symptoms are unique to the cylinder head. So try to get as many clues as possible during the diagnostic phase and troubleshoot suspected components when necessary. You will also find some troubleshooting tips for doing this in the appropriate sections.
So let’s get started.
|I. Blue smoke comes out of the exhaust pipe|
|II. My engine fails at idle|
|III. My engine fails|
|IV. I can hear a rattle|
|V. I can hear a rattling noise|
|SAW. I hear a tapping sound|
|VII. My engine has no power|
|VIII. Preventing Valve Train Problems|
I. Blue smoke comes out of the exhaust pipe: valve noise
A worn valve stem seal, such as a worn valve stem or guide, can allow oil to seep through the valve guide into the combustion chamber. If enough oil leaks out, this can cause:
- spark plug dirt
- cylinder misfire
- blue smoke through the exhaust pipe
You will usually notice the blue smoke during engine startup and deceleration.
How to Replace a Worn Valve Stem Seal
You can often replace worn valve stem seals without removing the cylinder head. Some shops fill the combustion chamber with compressed air to keep the valve in place while they replace the seals. At home, you may not have compressed air, but you can use a soft, thick caulking cord or similar cord instead.
- Put the transmission in Park (automatic) or Neutral (manual) and set the emergency brakes.
- Remove the spark plug from the cylinder you need to work on.
- Turn the piston you will be working on to BDC (bottom dead center). Rotate the crankshaft using a socket and breaker bar on the front crankshaft bolt. If necessary, remove all spark plugs to facilitate crankshaft rotation.
- Fill the cylinder with approximately 5 feet of wire. Use a large screwdriver to push the wire through the spark plug hole. The end of the wire should hang out of the spark plug hole after filling the cylinder so that you can remove it later.
- Bring the piston to TDC (top dead center) by manually turning the crankshaft. This allows the cable to press against the valve and hold it in place.
- Now you can use a valve spring compressor to replace the valve seal.
- Install the new valve seal.
- Reinstall the rest of the valve components.
- Turn the piston towards BDC and remove the rope.
Consult your vehicle’s repair manual, if necessary.
II. My engine fails at idle
Extremely high temperatures in the combustion chambers can damage the face or seat of …