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N62 8 Cylinder Coolant Pipe Replacement
 
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Pelican Technical Article:

N62 8 Cylinder Coolant Pipe Replacement

Nick Czerula

Time:

7 hours7 hrs

Tab:

$500

Talent:

*****

Tools:

Flathead screwdriver, T30, T45 Torx, 11mm socket (socket set), Allen bits

Applicable Models:

BMW E53 X5 Sport Utility (2000-06)
BMW E65 745i Sedan (2002-05)
BMW E65 Alpina B7 Sedan (2007-08)
BMW E66 745Li Sedan (2002-05)
BMW 545i Sedan (2004-05)
BMW 645Ci Coupe/Conv (2004-05)

Parts Required:

Intake manifold gaskets, secondary air pipes and mounts, coolant line, coolant pipe, plastic coolant pipe

Hot Tip:

Work with a cool engine

Performance Gain:

Seal coolant leak from faulty pipe O-rings

Complementary Modification:

Replace water pump and thermostat

The cooling system components of BMW E60 models with 8-cylinder engine include:

  • Radiator and coolant overflow tank.
  • Belt-driven coolant pump bolted to the front of the engine block.
  • Electric cooling fan attached to rear of radiator. The cooling fan is controlled by the engine control module (ECM) via an output final stage.
  • Automatic transmission cooler (heat exchanger).
  • Heater valve and heater core (for climate control).
  • Coolant level sensor inside expansion tank.
  • Coolant temperature sensor at cylinder head.
  • Radiator outlet temperature sensor
  • Coolant hoses and lines.

In the 8-cylinder engine a metal coolant pipe connects the water pump to the rear engine coolant passages. The pipe is sealed to the engine crankcase using rubber O-rings. These O-rings fail over time, causing a coolant leak in the valley of the engine. This coolant leak usually appears on the ground, at the rear of the engine in the transmission bell housing area. The pipe is tucked away under a valley pan that lives under the intake manifold. There are a few repair options for when the pipe O-rings fail. You can use a BMW factory part, but this requires removing the front timing cover, including the timing chains and front end of the vehicle. This method can take a few days to complete. A few aftermarket companies developed a way to repair the pipe without removing the timing cover housings. You cut the pipe out of the valley, then install an expanding pipe into the engine and secure the O-rings and pipe in place with pressure from the expanding pipe. On our subject vehicle, I am using one of the expanding pipe repair kits. They work great and save a ton of time and money. Before attempting this repair, read through the procedure and be sure you have the tools and the time it may take to complete the task.

Before doing any work on the cooling system, wait until the engine has cooled off.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

In this tech article, I will go over how to replace the coolant pipe on an N62 8-cylinder engine.
Figure 1

In this tech article, I will go over how to replace the coolant pipe on an N62 8-cylinder engine. The first major step is to remove the intake manifold (green arrow). See our tech article on intake manifold removing. The procedure will pick up with it removed. Remove the water pump. See our tech article on water pump replacing.

With the intake manifold removed you can now remove the intake manifold gaskets (green arrows).
Figure 2

With the intake manifold removed you can now remove the intake manifold gaskets (green arrows). Be sure to clean the sealing surface before installing new ones. You also have to remove the secondary air pipes (red arrows). The blue arrow points to a crack in the left side air pipe. Squeeze the air pipe plastic collar while pulling the pipes off the valves. The plastic retainers (yellow arrows) almost always break, so have replacements on hand.

Then detach the secondary air pipe from the air pump connecting hose (yellow arrow).
Figure 3

Then detach the secondary air pipe from the air pump connecting hose (yellow arrow). Squeeze the air pipe (red arrows) plastic collar while pulling the pipes off the hose. Remove the air pipe from the engine.

Next, the small coolant hose (yellow arrow) has to be removed.
Figure 4

Next, the small coolant hose (yellow arrow) has to be removed. It connects to each side of the engine valley. This hose is known for breaking, so have one on hand. Loosen the hose clamps (green arrows). Then pull the hoses off the engine and lay the hose aside.

Working in the engine valley, remove the four 13mm knock sensor fasteners (green arrows).
Figure 5

Working in the engine valley, remove the four 13mm knock sensor fasteners (green arrows). Then remove the knock sensors from the engine.

Pull the wire loom (green arrow) out of the valley pan.
Figure 6

Pull the wire loom (green arrow) out of the valley pan. It is mounted in two metal clips and pulls straight up when removing. You may have to transfer these clips over to your new valley pan. Double check the new part before discarding the old one.

Next, remove the 10mm coolant pipe fastener (green arrow).
Figure 7

Next, remove the 10mm coolant pipe fastener (green arrow). Then lift the coolant pipe (yellow arrow) up and lay it out of the way.

Working at the valley pan, remove the eleven 10mm fasteners.
Figure 8

Working at the valley pan, remove the eleven 10mm fasteners. You can leave the plastic pipe (yellow arrow) in the valley pan, as it has to be replaced anyway.

With the fasteners removed, lift the valley pan up and remove it from the engine.
Figure 9

With the fasteners removed, lift the valley pan up and remove it from the engine.

You now have access to the coolant pipe (green arrow).
Figure 10

You now have access to the coolant pipe (green arrow). Now is a good time to drain the coolant from the valley of the engine. Remove the block drain if you haven't already or suction the remaining coolant out.

Using a saw, cut the coolant pipe in the center.
Figure 11

Using a saw, cut the coolant pipe in the center. Cut the pipe in half, be careful not to come in contact with the engine while cutting.

Then remove the rear of the coolant pipe.
Figure 12

Then remove the rear of the coolant pipe. Then pull the front section out of the timing cover. Remove both sealing O-rings (green arrows) from the front and rear of the engine valley. Once the O-rings are removed, thoroughly clean the O-ring bores. Be sure there is no corrosion or left over O-ring. Use Scotch-Brite pads so you do not damage the sealing surface.

My replacement coolant pipe came with metal spacers / snap ring (blue arrows), a plastic collar (red arrow) large sealing O-rings for the ends of the pipe (green arrows) and small sealing O-rings for the center of the pipe (yellow arrows).
Figure 13

My replacement coolant pipe came with metal spacers / snap ring (blue arrows), a plastic collar (red arrow) large sealing O-rings for the ends of the pipe (green arrows) and small sealing O-rings for the center of the pipe (yellow arrows). I assembled the pipe as described in the provided directions. I don't want to attempt to rewrite the manufacturer's directions here, as they could change or need modification if the pipe evolves.

To summarize the install, the center pipe is sealed with O-rings, then the pipe is collapsed on itself.
Figure 14

To summarize the install, the center pipe is sealed with O-rings, then the pipe is collapsed on itself. You have to install O-rings in each side of the engine valley. Then expand the pipe in place and secure it with a snap ring. The plastic collar (red arrow) had to be orientated with the thick side up, so I marked it to make it easier to line it up. I installed the front of the pipe (blue arrow) first, then expanded it into the rear of the timing cover. Then the snap ring (yellow arrows) is slid into the locking groove (green arrow). This locks and seals the O-rings in place. I suggest using mild dish soap to lubricate the O-rings. It makes life much easier.

Next, install the new valley pan (green arrow) and tighten the fasteners.
Figure 15

Next, install the new valley pan (green arrow) and tighten the fasteners. I would begin to assemble the engine at this point. Once all of the cooling system components are on, pressure test the cooling system to be sure it is sealed. You don't want to have to go back in for a leak or a loose connection. Install the intake manifold with new gaskets, tighten the intake manifold fasteners, M6 fasteners: 10Nm (7 ft-lb), M7 fasteners: 15Nm (11 ft-lb), M8 fasteners: 22 Nm (16 ft-lb). Reassemble the intake components in the reverse order of removal. Be sure all hoses and electrical connectors are routed as they were when removed.

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Comments and Suggestions:
Sisnaz Comments: @Jeffery, I know this an older post, but the tale tell sign is if you see coolant leaking from the bell housing you've got a valley leak.

My question is, with the N62, should the valley be dry? It appears the predecessor engine M62 has a sealed valley pan lid and no transfer pipe so I'm assuming fluid runs through the valley ?. I'm wondering if the N62 valley pan lid is also supposed to be sealed, if anyone knows. Thanks!
November 5, 2016
  Followup from the Pelican Staff: The pipe sends coolant through the valley. Take note of the second to last image, you will see hols in the valley, when full of coolant (from a leak) this is where the coolant leaks from. - Nick at Pelican Parts  
Paul Murphy Homes Comments: It's the coolant vent pipe BMW part number 17127508013 - at least for my 2004 745
January 17, 2016
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
Paul Murphy Homes Comments: What's the part number for that small hose/water pipe indicated by the Yellow arrow in Figure 4?

ALSO - I would advise anyone doing this job to get a new bolts for the valley pan as a couple of mine were corroded and would have broken had I reinstalled. Also, I found the holes in which the bolts in the rear are installed in the valley pan needed to be chased to clean them up.
January 17, 2016
  Followup from the Pelican Staff: You noted: It's the coolant vent pipe BMW part number 17127508013

Thanks for the info. - Nick at Pelican Parts
 
Paul Murphy Homes Comments: If any of you purchase the URO pipe and you are disappointed because the sealed bag with the matress label that claims to have all the part in it and it does not have the plastic bits, look in the brown box. If you are like the 50% of folks that open it up from the end that does not have another plastic bag stuffed in it, open the other end.

Good luck.
January 17, 2016
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
Jeffrey Comments: How do you determine if you need this fix? What are the taletell signs?
December 8, 2015
  Followup from the Pelican Staff: Coolant leak from the valley of the engine. - Nick at Pelican Parts  

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Page last updated: Sat 12/3/2016 02:24:35 AM