Embark on the intricate process of cylinder head removal from the formidable Mercedes M273 engine. This comprehensive guide will empower you with the knowledge and expertise required to navigate this complex task. As we delve into the intricacies of this procedure, you will gain a thorough understanding of the critical steps involved, ensuring a successful and meticulous outcome.
Before embarking on this endeavor, it is paramount to gather the necessary tools and materials. A comprehensive socket set, torque wrench, and a variety of wrenches and pliers will form the foundation of your arsenal. Additionally, a high-quality gasket set, specifically designed for the M273 engine, will prevent future leaks and ensure optimal performance. meticulous preparation is essential, as it sets the stage for a smooth and efficient cylinder head removal process.
With preparation complete, the actual removal process can commence. Begin by disconnecting all electrical and fuel lines connected to the cylinder head. Carefully remove the valve cover, exposing the camshafts and valvetrain. Utilize the appropriate tools to release the camshaft bolts, allowing for the removal of the camshafts. Disconnect the exhaust and intake manifolds, followed by the removal of the cylinder head bolts. As you gently lift the cylinder head from the engine block, pay meticulous attention to prevent any damage to the mating surfaces. The cylinder head is now successfully removed, paving the way for further inspection, maintenance, or repair.
Preparing the Engine for Cylinder Head Removal
Before removing the cylinder head, it is crucial to properly prepare the engine. This step ensures a smooth and successful removal process, minimizing the risk of damage or complications.
Disconnecting Electrical and Fluid Lines
Begin by disconnecting all electrical connectors and vacuum hoses attached to the cylinder head. Note the location of each connection for easy reassembly later on. Next, drain the engine oil and coolant to prevent spills or contamination. Finally, disconnect the fuel lines and fuel rail, ensuring to seal off any open ends to prevent fuel leaks.
Removing Engine Accessories
Remove all accessories mounted on or near the cylinder head, such as the intake manifold, exhaust headers, camshaft covers, and any sensors or wiring harnesses. Carefully disconnect and label all electrical connections and hoses associated with the accessories being removed.
Positioning the Engine
Position the engine at its highest possible point using a lifting device. This provides ample clearance for removing the cylinder head bolts and lifting the head off the engine block. Ensure that the engine is stable and securely supported before proceeding further.
Removing the Cylinder Head Bolts
Locate and remove all cylinder head bolts in a sequence specified by the manufacturer. Follow the tightening sequence in reverse order when removing the bolts. Use a torque wrench to apply the correct amount of force during removal. Be cautious not to drop any bolts into the engine, as they can be difficult to retrieve.
Table: Cylinder Head Bolt Tightening Sequence
| Bolt Number | Tightening Sequence |
|---|---|
| 1 | 12 Nm |
| 2 | 15 Nm |
| 3 | 20 Nm |
| 4 | 25 Nm |
Removing the Intake Manifold
1. Disconnect the Battery
Begin by disconnecting the negative terminal of the battery to prevent any electrical mishaps during the process.
2. Remove the Intake Manifold
- Unbolt Accessory Brackets: Locate and unbolt any accessory brackets connected to the intake manifold, such as the power steering pump and alternator.
- Remove Air Intake Hoses: Detach all air intake hoses and vacuum lines leading to the intake manifold.
- Unbolt Intake Manifold Bolts: Using a socket wrench, loosen and remove the bolts securing the intake manifold to the cylinder head.
- Carefully Lift Off Manifold: Once all bolts are removed, gently lift off the intake manifold and set it aside on a clean surface.
- Clean Surfaces: Before proceeding to the next step, thoroughly clean the mating surfaces of the cylinder head and intake manifold to ensure a proper seal upon reassembly.
| Tools Required: |
|---|
| Socket wrench |
| Ratchet |
| Assortment of sockets |
Disconnecting Coolant Hoses and Lines
Carefully disconnect the coolant hoses and lines from the cylinder head. Use a pair of pliers or a wrench to loosen the hose clamps, then gently pull the hoses off the fittings. Be careful not to damage the hoses or the fittings.
3. Removing Coolant Lines from the Rear of the Engine
Disconnect the coolant lines from the rear of the engine. These lines are located on the back of the cylinder head, and they connect to the coolant pump and the thermostat housing. To disconnect the lines, use a pair of pliers to loosen the hose clamps, then gently pull the hoses off the fittings. Be careful not to damage the hoses or the fittings.
| Hose/Line | Location |
| Heater hose | Top rear of engine |
| Thermostat housing to water pump hose | Lower rear of engine |
| Coolant bypass hose | Right rear of engine |
Once all of the coolant hoses and lines have been disconnected, you can proceed to remove the cylinder head.
Removing the Valve Cover
To remove the valve cover, follow these steps:
- Disconnect the negative battery terminal.
- Remove the intake manifold.
- Remove the spark plugs.
- Remove the bolts that hold the valve cover in place.
Removing the Valve Cover Bolts
There are 10 bolts that hold the valve cover in place. They are located in the following positions:
Bolt Position Torque (Nm) Front left 10 Front right 10 Middle left 10 Middle right 10 Rear left 10 Rear right 10 Top left 10 Top right 10 Bottom left 10 Bottom right 10 - Carefully lift the valve cover off the cylinder head.
- Use a high-quality RTV silicone sealer that is specifically designed for automotive applications.
- Make sure the mating surfaces are clean and dry before applying the sealer.
- Apply the sealer in a continuous bead, ensuring that there are no gaps or voids.
- Allow the sealer to tack up slightly before positioning the cylinder head on the block. This will help to keep the sealer in place and prevent it from squeezing out when the head is tightened.
Removing Cylinder Head Bolts
1. Position the engine at Top Dead Center (TDC) of the compression stroke for the cylinder you are working on.
2. Remove the valve cover.
3. Remove the timing chain cover.
4. Remove the camshafts.
5. Identify the cylinder head bolts. There are 10 bolts that hold the cylinder head to the engine block. The bolts are located in two rows of five bolts each. The bolts in the front row are longer than the bolts in the rear row.
Here is a table summarizing the cylinder head bolt locations:
| Bolt Location | Bolt Length |
|---|---|
| Front Row | 120 mm |
| Rear Row | 100 mm |
6. Loosen the cylinder head bolts in two stages. First, loosen the bolts one-quarter turn at a time. Then, loosen the bolts one-half turn at a time until they are completely loose.
7. Remove the cylinder head bolts.
8. Lift the cylinder head off of the engine block.
Safely Lifting and Removing the Cylinder Head
1. Safety Precautions
Always wear appropriate safety gear, such as gloves, safety glasses, and a face shield.
2. Tools and Materials
Gather the necessary tools, including a 1/2-inch socket wrench, 10mm socket, 13mm socket, 15mm socket, and a torque wrench.
3. Engine Preparation
Disconnect the battery and drain the coolant. Remove the spark plugs and disconnect any hoses or wires connected to the cylinder head.
4. Removing the Valve Cover
Unbolt the valve cover bolts and remove the valve cover. Remove the camshaft caps and slide out the camshafts.
5. Removing the Cylinder Head Bolts
Locate the cylinder head bolts and carefully unscrew them in the reverse order of tightening. Refer to the vehicle’s service manual for the specific torque specifications.
6. Lifting and Removing the Cylinder Head
Use a cylinder head lifting tool or a suitable pry bar to carefully lift the cylinder head off the engine block. Avoid damaging the head gasket or any other components.
To remove the cylinder head completely, follow these steps:
| Step | Description |
|---|---|
| A | Install two long bolts into the lifting holes on the cylinder head. |
| B | Attach a chain or strap to the bolts and lift the cylinder head off the engine block. |
| C | Carefully guide the cylinder head out of the vehicle. |
Cleaning the Cylinder Head and Engine Block
Cylinder Head Cleaning
Thoroughly clean the cylinder head to remove any carbon buildup, oil, or debris. Use a wire brush and solvent to scrub away any visible deposits. Ensure the combustion chambers, intake and exhaust ports, and valve seats are spotless.
Valve Cleaning
Carefully clean the valves using a valve seat cutter or scraper. Remove any carbon buildup or debris from the valve faces and seats. Ensure the valves move freely within their guides and that the valve clearances meet specifications.
Engine Block Cleaning
Clean the engine block’s top surface where the cylinder head bolts. Remove any old gasket material or debris using a scraper or wire brush. Ensure the surface is flat and free of any unevenness.
Engine Block Screw Holes Cleaning
Thoroughly clean the engine block screw holes to remove any thread sealant or debris. Use a thread chaser or tap to remove any rust or corrosion from the threads. Ensure the bolts can be easily inserted and tightened.
Water and Oil Passageways Cleaning
Flush out the water and oil passageways within the cylinder head and engine block. Use a cleaning solvent or compressed air to remove any debris or obstructions. Ensure the coolant and oil can flow freely without any restrictions.
Engine Block Surface Preparation
Carefully inspect the engine block surface where the cylinder head bolts. Ensure it is flat and free of any warping or damage. If necessary, use a surface plate and straight edge to measure and correct any unevenness.
Apply Gasket Sealant
Before mounting the cylinder head, apply a thin layer of gasket sealant to the engine block surface. Follow the manufacturer’s instructions and ensure the sealant is applied evenly. This will help prevent leaks and ensure a proper seal.
Inspecting the Cylinder Head and Engine Block
Inspecting the Cylinder Head
Once the cylinder head is removed, inspect it thoroughly for any damage or wear. Look for cracks, warping, or any other irregularities. Pay particular attention to the valve seats, guides, and camshaft journals. If any significant damage is detected, the cylinder head may need to be replaced or repaired.
Inspecting the Engine Block
Similarly, inspect the engine block for any damage or wear. Check for cracks, warping, or any other irregularities on the surface of the block. Pay special attention to the cylinder walls, camshaft bearings, and oil passages. If any significant damage is found, the engine block may need to be replaced or repaired.
Inspecting the Cylinder Head Gasket Surface
The mating surface between the cylinder head and the engine block is critical for proper engine operation. Inspect this surface carefully for any scratches, gouges, or other irregularities. If the surface is not perfectly flat, it can lead to a compromised seal and potential engine problems. Ensure the surface is cleaned and free of any debris before reassembly.
| Cylinder Head Gasket Surface Condition | Recommended Action |
|---|---|
| Minor scratches or gouges | May be acceptable if depth is minimal; smooth with fine sandpaper |
| Significant scratches or gouges | Resurface the cylinder head at a machine shop |
| Warped or uneven surface | Replace the cylinder head or have it professionally resurfaced |
Reassembling the Cylinder Head
Once the cylinder head is clean and ready to be reassembled, follow these steps:
9. Apply a Thin Bead of Sealer
Using a clean rag, apply a thin, consistent bead of RTV silicone sealer to the mating surface of the cylinder head. Be careful not to apply too much sealer, as this can block oil and coolant passages. You want just enough sealer to fill any irregularities in the surface and create a gasket-like seal between the cylinder head and the block. Here are some additional tips for applying the sealer effectively:
Post-Removal Maintenance and Inspection
Inspect Valves and Valve Seats
Thoroughly inspect the valves and valve seats for any signs of wear, damage, or carbon buildup. Replace any worn or damaged valves and re-seat or replace the valve seats if necessary.
Clean Combustion Chamber
Use a solvent and a brush to remove any carbon deposits or other debris from the combustion chamber. Ensure that the chamber is completely clean before reassembling the head.
Check Cylinder Bores
Inspect the cylinder bores for any scoring, scuffing, or wear. If any issues are detected, consult a professional machinist to determine if the block needs to be bored or honed.
Inspect Piston Rings
Carefully inspect the piston rings for wear, breakage, or sticking. Replace any worn or damaged rings and ensure they move freely in the piston grooves.
Measure Cam Timing
Reinstall the camshafts and ensure that the cam timing is correct. Use a dial indicator or other precision tool to measure the timing and adjust it as necessary.
Check Head Bolt Torque
Tighten the head bolts to the specified torque following the correct tightening sequence. Refer to the manufacturer’s guidelines for the proper torque values.
Apply Sealant and Reassemble
Apply a thin bead of high-temperature sealant to the mating surface of the cylinder head. Position the head carefully and lower it onto the block. Install all necessary bolts and torque them to specification.
Reinstall Timing Components
Install the timing chain, sprockets, and other components as per the manufacturer’s instructions. Ensure the timing is correct before starting the engine.
Inspect Oil and Coolant
Check the oil and coolant levels and replenish them if necessary. Monitor the engine closely for any leaks or abnormalities after starting.
Additional Notes
Before reassembling the engine, it is crucial to thoroughly clean all parts and components. Use a compressed air gun to remove any loose debris or contaminants. Additionally, if the head was damaged beyond repair, it may be necessary to replace the entire engine.
| Component | Inspection Points |
|---|---|
| Cylinder Bores | Scoring, Scuffing, Wear |
| Piston Rings | Wear, Breakage, Sticking |
| Valves | Wear, Damage, Carbon Buildup |
| Valve Seats | Wear, Damage, Leaking |
How to Remove Cylinder Head from Mercedes M273 Engine
Step 1: Safety First
Before starting work on the engine, remove the negative terminal of the battery and drain coolant from the system.
Step 2: Remove Upper Intake Manifold
Disconnect all electrical connections and hoses from the upper intake manifold. Remove intake manifold bolts and lift the manifold to expose the cylinder head.
Step 3: Remove Valve Cover Assemblies
Unbolt valve cover assemblies from the cylinder head. Lift off assemblies and remove camshafts by carefully sliding them out while supporting rocker arms.
Step 4: Remove Timing Chain
Assemble a locking tool for the crankshaft and use it to align the timing marks. Remove the tensioner and slide the timing chain off the camshaft and crankshaft sprockets.
Step 5: Loosen Cylinder Head Bolts
Follow the reverse torque sequence to loosen cylinder head bolts in increments. Repeat the sequence until all bolts are removed.
Step 6: Remove Cylinder Head
Using a pry bar, carefully pry the cylinder head off the engine block at each corner. Once loose, lift the head and remove it from the engine.
People Also Ask
How much does it cost to remove a cylinder head?
The cost of removing a cylinder head can vary depending on the vehicle make, model, and year, as well as the complexity and labor involved. Expect to pay between $1,000 to $2,500 for the repair.
Can I remove the cylinder head myself?
While it is possible to remove a cylinder head yourself, this is a complex task that requires specialized tools and knowledge. Unless you have significant mechanical experience and confidence, it is recommended to leave this task to a professional mechanic.
What are the signs of a blown cylinder head?
Symptoms of a blown cylinder head can include excessive white smoke from the exhaust, coolant leaking into the oil or combustion chamber, overheating, and poor engine performance. If you suspect a blown cylinder head, have your vehicle inspected and repaired promptly.
