:iagree:

1. Some owners follow the rule "wait until it breaks" and fix accordingly based on their budget (OE, OEM or aftermarket)

2. Some owners like to be proactive based on trending, copy what others have done or create their own plan for executing preventive maintenance

3. Some owners are OCD with regular maintenance and preventive maintenance

4. Some owners does not care, both regular maintenance and preventive maintenance

I am in between 2 and 3

Good luck to the OP!

:) I think you may have inadvertently flipped the pre & post facelift types of alternators around...so just for the sake of clarification for those that may not know...the breakdown of alternators vs e53 engines are:

• M62TU B44 - water cooled alternator
• M62TU B46 - water cooled alternator
• M54 B30 - air cooled alternator
• M57 D30 - air cooled alternator
• M57N D30 - air cooled alternator
• N62 B44 - air cooled alternator
• N62 B48 - air cooled alternator

BTW assuming that the 4.4 in your handle is indication that you have the 4.4 liter engine in your car...by not having a signature or vehicle info that indicates what model/model year/build date you have...it's not clear if you have the M62TU 4.4 or the N62 4.4 (totally different engines as you know). Identifying which model/model year/build date you have helps those that find your posts (doing a search) or when you reply...have a perspective of what you say or have done etc. If you mod or update your X...they can immediately know if it can apply to their model or not based on where yours & theirs falls within the production date range. :)

Do I understand correctly--credentials mean you are correct and my opinion is confirmation of ignorance about this subject?

That is not math. That is a supposition which means it could be true as well as false. It is a supposition of an imaginary horrible.

Here's another supposition---inspected the components of the cooling system. Belt was bad. Replaced belt $25.00 vs. $400 to $600 for overhaul. Saved as much as $575 by replacing the belt only and I never blew a head gasket because I look at the garage floor when I back out, I check my gauges when I drive, the coolant level when I get gas and listen for noises that shouldn't be there.

I have acknowledged your opinion but it is only an opinion. I even acknowledged it is best practice. I have a different opinion-Just because one only replaces the part that has failed does not mean one is foolish or will suffer terrible consequences.

This is the crux of the issue. Many people do exactly that, i.e., replacing only the bad part and later regretted. All you have to do is go to bimmerfest E39 forums and you will see countless regretting because they lost the engine. Why? Replaced ONLY the let's say the WP, 2 weeks later the reservoir blew on the highway with massive coolant loss ---> head gasket blew.

I don't blame you, you own a V8, which has its own issues. But the cooling system in the I6 is the Achilles heel.

I understand your point: replace only the bad part. In a way I am the same replacing ONLY the bad part but as I mentioned, the cooling system is the exception. They fail like clockwork.

So your advice of replacing only the bad part is the correct advice from a technical standpoint but it is false economy on the practical standpoint.

Replacing whichever parts are generally involved in failure is plain common sense.

CN90 - your example of the cooling system systemic issue on the E39 is an excellent one. Where parts within a system are known to fail, only a sub0standard technician would replace only the failed part in that system. The reason being, they are generally asked to warrant their work, and how can that occur when they know there are other failure-prone elements they have not at the least inspected, at best replaced.

Do it once, do it right.

To misquote an old adage - a rich man fixes something once. A poor man fixes something many times.

I have acknowledged at least twice that best practice is to do an overhaul of the system.

As you know, techs replace only what is authorized by the owner. I think you can say a good tech should/would advise one of the risk (significantly less than a certainty) of doing less than an overhaul. There probably a tech or two somewhere that wouldn't take the work unless they did the overhaul. I don't know of him. Yes, they stand by their work which means if they didn't do the work they don't stand by it.

From my point of view the following would be appropriate : I feel strongly that the cooling system should be overhauled every X miles or X years. That is because the cooling system failures can cause very expensive engine problems that I have seen occur when the system is not overhauled. While the cooling system components can have very different life cycles it is not unusual that they fail near the same time, especially if the vehicle has overheated. There are those that successfully replace components as they fail. That is a higher risk scenario but a direction you might want to consider. If you choose to do so be sure you understand how and how often to inspect the cooling system so you are more likely to recognize a problem before it happens. In cases, such as a bad water pump, several other cooling system components will be at least partially removed or accessible. That being the case it will be more economical in the longer run to replace those parts as well.

I'm done.

Although I am an advocate for cooling overhaul, there are situations when a piece-meal approach is fine too, when it meets the following conditions:

1. The owner is on a very tight budget.

2. The owner is very careful and open the hood once a week to check the cooling system because this is a high-mileage vehicle.

3. The owner does not drive long-distance trips out of town.

4. The owner is mechanically and can tackle this job again and again.
The only downside is every time the cooling system is opened, you lose coolant, which is about $12/gallon for Prestone, not a bad price.
Or you can recuperate the coolant and re-use it (I use coffee filter paper to filter it when I re-use coolant).

5. So let's say the only wrong is the WP. Fine, replace only the WP.
Check all other stuff (belts, rollers, tensioners, fan clutch, fan blade), if they seem fine, re-use them.
The rollers bearing can be re-packed with grease for minimal cost of grease. I wrote the DIY (re-greasing roller) in bimmerfest E39 forum.

6. The tstat is hard to test while in the vehicle. So every time the WP is replaced, the tstat should be replaced too for 2 reasons:
a. At 100K, the tstat is unreliable and can lock up any time.
b. The tstat housing is plastic and can blow any time.

7. The reservoir is the same, it is plastic and typically burst at 130K or so.


So for a vehcile > 130K, the basic basic bare-bone mimimum is:
- WP (HEPU is $60 at eeuroparts.com)
- Tstat (Wahler is $60)
- Reservoir ($90 at dealer, do not use any other brand)

I mentioned the brand name because this is the best bang for the buck.

:iagree:

Am I the oddball in the bunch since I've got over 260,000 miles on the original water pump with no indication of any engine cooling issues?

2002 X5 3.0 260,590 miles
2004 325i 115,000 miles

Okay, I need your guys help again!

The tools finally came in to take the fan out.

I was able to put the serpentine belt back on... and I found the leak under the engine. What do you guys think is causing the leak?

Leak Part 1

https://www.youtube.com/watch?v=ugx34Tnsej8

Leak Part 2

https://www.youtube.com/watch?v=sbXlyXqC5Us


Also the pulley that spins the fan is really loose, is there a way I can tighten it?

http://i.imgur.com/6E0Ygwsl.jpg