Valve Train Diagnosis C/K 800, B7
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
DEFINITION: A light tapping noise with a frequency equal to one half engine speed, or any other varying frequency. | ||||
1 | Is there valve train noise? | -- | Problem solved. | |
2 | Check for a high engine oil level. An engine with the oil level above the FULL mark may allow the crankshaft counterweights to churn the oil into foam. When foamy oil is pumped into the lifters, the lifters become noisy. A solid column of oil ensures proper lifter operation. Is the oil level too high? | -- | Drain oil as required. | |
3 | Check for a low engine oil level. An engine with the oil level below the ADD mark may allow the oil pump to pump air at high engine RPMs. Is the oil level too low? | -- | Add oil as required. | |
4 | Check for proper engine oil pressure. Refer to Engine Mechanical Specifications and Oil Pressure Diagnosis and Testing . Is the engine oil pressure within specifications? | -- | ||
5 | Check the oil pump screen for damage or a loose fit to the oil pump. Are the components worn or damaged? | -- | Replace the components as required. | |
6 | Check for a damaged oil pump or loose mounting bolts Refer to Oil Pump Clean and Inspect Are the components worn or damaged? | -- | Replace the components as required. | |
7 | Remove and inspect the valve rocker arms, valve rocker arm shafts, and pushrods. Refer to Valve Lifters and Guides Clean and Inspect . Are the components worn or damaged? | -- | Replace the components as required. | |
8 | Remove and inspect the valve lifters and guides. Refer to Valve Lifters and Guides Clean and Inspect . Are the components worn or damaged? | Replace the components as required. | ||
9 | Check the camshaft lobe lift. Refer to Camshaft and Bearings Cleaning and Inspection and Engine Mechanical Specifications . Are the components worn or damaged? | -- | Replace the components as required. | |
10 | Remove the engine front cover and inspect the timing chain and sprockets for excessive wear or damage. Refer to Timing Chain Wear Check and Timing Chain and Sprockets Clean and Inspect Are the components worn or damaged? | -- | Replace the components as required. | |
11 | Perform a complete disassembly of the engine and inspect all internal engine components. Are the components worn or damaged? | -- | Replace the components as required. | |
Valve Train Diagnosis Other
A light tapping at one-half engine speed, or any varying frequency, can indicate a valve train problem.
These tapping noises increase with engine speed.
Before attempting to judge the valve train noises thoroughly warm up the engine. By doing this you will bring all engine components to a normal state of expansion. Also, run the engine at various speeds and listen for engine noise with the hood closed while sitting in the driver's seat. The causes of the valve train noise include the following conditions:
| • | Incorrectly adjusted valve lash |
| • | Low oil pressure |
| • | Loose valve rocker arm attachments |
| • | Worn valve rocker arm and/or pushrod |
| • | Broken valve spring |
| • | Sticking valves |
| • | Lifters worn, dirty or faulty |
| • | Camshaft lobes worn |
| • | Worn valve guides |
| • | Worn or damaged valve keys |
| • | Bent pushrods |
