This article gives detailed instructions on replacing the valley pan gasket in a BMW vehicle with the 8 cylinder N62 engine. Even though we used a 2005 645ci to perform this repair, this article can be applied to any vehicle with the BMW N62 8 cylinder engine including 5,6,7 and X5 models with minor modifications to the repair steps.
A BMW N62 valley pan gasket replacement may cure the coolant leak dripping from the back of the engine.
If you own a V8 BMW produced from 2000 through 2010, then you most likely have the “new generation” N62 eight cylinder engine. The N62 engine was considered a large technological leap over its predecessor, the M60/62 V8. One of the most significant advancements was an optimized engine cooling system featuring an improved cross-flow coolant pattern through the engine block. This improved coolant flow created a more even temperature distribution around the cylinders and ultimately a more efficient engine.
In order to properly channel coolant from the front water pump to the rear of the engine, the BMW N62 relies on a valley pan – a cast aluminum cover that runs down the centerline of the engine block between its cylinder heads (or its “valley”). The valley pan is actually a “U” shaped conduit, allowing coolant to flow efficiently without the need of pipes or hoses. The valley pan is sealed to the engine block by an integrated rubber gasket. Over time, age and heat causes the valley pan gasket to become hard and brittle allowing coolant to seep out around its edges. A leaking valley pan usually leaves a trail of coolant on the engine block, making it very easy to diagnose.
The classic symptom of a leaking BMW N62 valley pan gasket is coolant leaking from the rear of the engine. Since the engine block is sloped slightly to the rear, any leaking coolant will find its way to the rear of the motor and onto the ground.
A BMW N62 valley pan gasket replacement requires removing the intake manifold and the water pump from the vehicle. It is a time consuming repair, but is very “doable” for any home mechanic with average abilities.
Since the water pump and coolant return pipes must be removed for this repair, now is an excellent time to do some maintenance to your cooling system. At the very least you should replace the small return cooling pipe that mounts to the back of the water pump. We strongly recommend replacing the water pump and thermostat as well while they are off of the car. Spending a few extra dollars now will save you from having to repeat this repair later on down the line.
1. Valley pan (required) – The BMW N62 valley pan has an integrated rubber gasket…you can’t purchase it separately. Therefore you have to replace the entire valley pan when performing this repair. We give you several affordable options based on your brand preference and budget.
2. Coolant pipes (optional) – Although not required, we strongly recommend replacing your coolant return pipes while you have the engine apart. Replacing your coolant return pipes is cheap insurance against having to disassemble your engine again to fix a leak.
2. Water pump and thermostat (optional) – Once again, replacing these parts is not required but highly recommended. A new water pump and thermostat for the N62 engine are inexpensive, and since both need to be removed to complete this repair, it only makes sense to replace them.
In order to perform a BMW N62 valley pan replacement, the water pump/thermostat assembly must be removed from the front of the engine. This is because the two water pump coolant return pipes have to be cleared out of the way to get the valley pan our of the engine block. The pipes cannot be removed with the water pump in place.
- To remove the water pump/thermostat from your N62 engine, please see our article BMW N62 Water Pump Replacement – 8 Cylinder 5,6,7 and X5 Series before proceeding to the next section.
After you have removed the water pump/thermostat assembly from the engine, you will need to remove the intake manifold. The valley pan is located in the center of the engine block, directly under the intake manifold.
- To remove the intake manifold from your N62 engine, please see our article BMW N62 Intake Manifold Gasket Replacement – V8 5,6,7 and X5 Series before proceeding to the next section.
After removing the water pump and intake manifold, replacing the valley pan is fairly simple. We cannot stress enough cleaning the engine surface prior to installing the new valley pan. Just a small amount of dirt or debris can keep the new pan from sealing correctly.
- Identify the heater return pipe that runs down the right side of the valley pan. Using a 10mm socket wrench, remove its mounting bolt.
- Use a flat blade screw driver to release the return pipe’s metal locking clip and remove it from the vehicle.
- Unclip the positive battery cable from the top of the valley pan. Be sure not to lose the clips…you will reuse them on the new pan.
- Using a 10mm socket wrench, remove the 12 valley pan anchor bolts.
- Grasp the pan and carefully remove it from the engine block.
- Use some CRC Brakleen to thoroughly clean the valley pan mounting surface before installing a new pan. the surface must be completely clean to avoid future leaks.
Installing a new valley pan is very straight forward with no special procedures or steps. We strongly recommend replacing the water pump return pipe as well as the intake manifold gaskets during reassembly. We have provided a handy checklist below with the reassembly steps along with important torque values.
BMW N62 Valley Pan Reassembly Checklist
***The following steps were performed on a 2005 645ci…other models may vary.
- Carefully install a new valley pan and torque its mounting bolts to 10.5 Nm (7.75 ft-lb).
- Clip the positive battery cable back onto the valley pan.
- Reinstall the heater return pipe. Make sure that its locking clip is closed and it “clicks” securely into its fitting. Replace its mounting bolt and torque to 10.5 Nm (7.75 ft-lb).
- Replace the intake manifold. Please refer to our article BMW N62 Intake Manifold Gasket Replacement – V8 5,6,7 and X5 Series for installation instructions.
- Replace the water pump/thermostat assembly. Please see our article BMW N62 Water Pump Replacement – 8 Cylinder 5,6,7 and X5 Series for installation instructions.