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What are the pros/cons of the various BMW E39 replacement water pumps?

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#1 · (Edited)
What are the pros/cons of the various BMW E39 replacement water pumps?

I'll start with an overall summary (based purely on Internet research) but I don't profess this keyboard list to be accurate (until vetted by you guys).

I think these are the fundamental options:
a) water pump, paper gasket, & rubber o ring with composite impeller (OE & OEM & OES & OES Replacement)
b) water pump, paper gasket, & rubber o ring with metal impellers (Aftermarket)

Are these the known suppliers? What are the pros/cons of each?

BMW E39 Water Pump Suppliers:
--- top tier (I think) ---
1. Stewart EMP (some say they beef up the bearings to handle the metal)
2. Hepu (Cam like's em but I don't know much about 'em)
3. Geba (heavy cast metal impeller, bearings sometimes fail)
4. Graf welded steel impeller (better but also occasional bearing failure)
5. GMB (I think this is OE with composite plastic impellers???)
--- lower tier (I think) ---
6. Hella (I think this is OEM with composite plastic impellers)
7. Bosch (I don't know of any users who reported back on these)
8. Beck Arnley (they sell 'em but I don't know anyone using them)
9. Airtex (again, they sell 'em, but we'd have to hear from users first)
10. AC Delco (same as the last two above, they sell 'em)
11. A1 Cardone (they sell 'em, don't know much about 'em)
12. ??? please correct this list as needed so we all benefit ???
 
#2 ·
I got my water pump at AutohausAZ. It was the EMP/Stewart high performance pump with metal impeller. Theoretically lasting longer and it has a lifetime warranty. I felt the few extra $$ were justified for peace of mind and so far so good about almost 20k on it. Anything to prolong doing another cooling overhaul anytime soon.
--

BMW High Performance Water Pump

The BMW High Performance Water Pump is a direct replacement pump designed to fit a wide range of BMW engines with no modifications. That includes accepting the Factory Fan Clutch. The front of the BMW High Performance Water Pump is stock appearing giving it that classic BMW look while the back is all business.

* Up to 20% increase of water flow over stock pump
* Twice as efficient as factory pump
* Much less parasitic drag than other pumps
* Racing or Stock Factory Replacement applications
* Stainless steel impeller
* Heavy duty bearing
* High quality water seal

Image
 
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#3 ·
This is a very timely posting, Donna! I'm in the throes of overhauling my cooling system (previous owner never did anything, even the belts are original; 139K miles so far) and I had the very same questions. I've been leaning toward the EMP/Stewart so I will take Mack's advice and include this on my list of parts to get. Thanks to you both!
 
#5 ·

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#11 ·
I have had HEPU Water Pump in my 1998 528i now for four (4) years, rock solid no issues.

I guess Graf is good too.

The Volvo people love HEPU. Just Google "Volvo forum Hepu".
Some of the threads supporting HEPU:

http://volvoforums.com/forum/showthread.php?t=8843
This came from a Volvo tech:
That (HEPU) is what we use when we replace the water pumps. Never have any problems with them.
Click to expand...
 
#6 ·
I put an OES (Original Equipment Supplier) water pump in. Out came a composite with 96K miles and in went the same thing. My thinking is that a composite pump impellers can be held to much tighter tolerances than a metal or cast one. So efficiency should be better.

Now if I was to use EVANS NPG+ in MA with -20F temps in the winter, I would have used a metal one so that there is no chance of breakage pumping slush around until it warms up.
 
#7 ·
Because stock BMW cooling parts are world renown for their quality. Blubeee do yourself a favor and get the EMP/Stewart HP
 
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#10 ·
Great thread on parts selection. :thumbup: Parts selection can be a tough decision for e39 owners. Especially since we have to replace so many parts!! :rofl: How much better is "the best" and is it worth the extra cost. :dunno: And with the e39, we have the good fortune to have a multitude of aftermarket choices (which is really a good thing) on almost every part.



+1, Good Advice based on solid rationale!!! :rofl:

bluebee said:
what's killing me is I can't make decisions easily. I need overwhelming advice either way
Click to expand...
FWIW, here's how I prioritize my decision making when it comes to replacement parts for my e39:
1. If the part failure can kill my car (e.g. cooling system), it gets the best parts $$ can buy.
2. If the part failure means I have to redo the job later (e.g. thrust arm bushings), I'll strongly consider the better part depending on the extra cost & complexity of the job to avoid redoing it.
3. If the part means higher vehicle performance (e.g. shocks, tires, etc.), I'll consider it but in most cases will probably pass as I don't drive that fast anymore.

Others probably put performance at the top of the list but to each his own. For me, getting there is more important to me than getting there faster.
 
#8 ·
Bimmer magazine also recommends the EMP Stewart, FWIW, and that's what I bought.

I just killed my wallet by buying all the other necessary cooling system parts, closely following all the advice on this board, shopping several vendors, saving some $$ here, spending a little more $$ there... very time consuming process (Bluebee, I was also afraid to make the wrong choices but I feel good knowing I did my best) and now I'm overly anxious to dig in. But, it's time for bed...
 
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#15 ·
Bluebee, I feel your pain when it comes to deciding on parts when there is more than 1 to pick from.. On this specific issue I have a small tidbit. At 120K, I replaced my original wp with a Bosch while dong a cooling system revamp. Two weeks later developed a leak that originated from the wp. Replaced it with the original that I took out and no leak. Now I have to do the job again at 200K, but at 160K the original BMW one is still running strong.
 
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#16 ·
At 160K, the original Wp lives on borrowed time!

Bosch strength is in sprak plugs, ECU etc. Now they get into the Water Pump market, it is another story.

For Water Pump, I have had HEPU now for 4 years, zero problems. Volvo people use HEPU alot and rock solid. My recommendation is do a cooling overhaul at 160K and change anything in there that is OEM.
 
#19 ·
This ONLY assuming you do all your own work and don't mind being stranded anywhere at inopportune times.

I'm not saying stock replacement parts are half-assed. But if you have the opportunity to replace them with better than OEM then why not do it? I guess I just don't understand your logic. :dunno:
 
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#24 ·
Papabear426 said:
went with Stewart & NPG+ at 130K, all other stock/Behr stuff.
Click to expand...
Kudos to you.

I didn't have the guts to try this low-pressure experiment.

BTW, when you remove your old Behr/Heat expansion tank, can you slice it in half and let us know what it looks like inside for this thread?
- Request for another Behr expansion tank autopsy (1)
 
#28 ·
Yeah man. I want to do the NPG at some point. Stewart HP still going strong at 30k+ miles.
 
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#30 ·
I'm planning on it. At least I know my trani will last forever. According to BMW anyways.
 
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#31 ·
There is a very good discussion of the various water pumps in part 1 of this video referenced today by bobdmac:

BMW Cooling System Failure Points, Part 1 (e36, e46, e34, e39):

BMW Cooling System Failure Points, Part 2 (e36, e46, e34, e39):
 
#36 ·
bluebee said:
There is a very good discussion of the various water pumps in part 1 of this video referenced today by bobdmac:

BMW Cooling System Failure Points, Part 1 (e36, e46, e34, e39):
Click to expand...
That's a great video. Damn I'm glad I went with the Stewart EMP.
 
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#32 ·
For the waterpump record, this thread discusses the fallibility of both the plastic OEM and tack-welded metal Graf versus the cast metal Geba water pump impellers ...
- Catastrophic water pump faliure!

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#34 ·
Appears as though the Stewart/EMB is only for a 525 or 530. Of the remaining options any recommendations for a 2003 540/6 (68k miles) as I think mine is beginning to crater? I'm leaning toward metal versus composite option. Don't worry, I'll be replacing the entire cooling system at the same time. :thumbup:
 
#35 ·
Way to be proactive! :thumbup:
 
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#38 ·

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