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

For the crosslinked record, this thread today discusses some of the various water pump brands:
> E39 (1997 - 2003) > 2001 525i Overheating

Originally Posted by cn90

IMHO, Stewart is expensive and a waste of money. Standard WP like HEPU or OEM easily lasts 80-100K miles.

If the Stewart for mucho extra money doesn't give you extra emotional comfort, buy another pump with a metal impeller. You'll be fine with that as a reliable pump.
I got the Stewart myself because it's a fine piece of well made machinery.

The Stewart is really finely made, if you get a chance to hold 2 side by side, its amazing

Checkout the pump
http://www.bimmerzone.com/BMW_Perfor...STE-30330.html

Originally Posted by GoForthFast

If the Stewart for mucho extra money doesn't give you extra emotional comfort, buy another pump with a metal impeller. You'll be fine with that as a reliable pump.
I got the Stewart myself because it's a fine piece of well made machinery.

There are pictures of a recently failed Bosch waterpump over here today:

Originally Posted by Dilligaf-IA

I replaced the entire cooling system back in May of this year. Drove the car daily since then, went on a couple good trips over the summer, and then I started having issues with it overheating last week. This was after winding it out through the gears one day, but nothing too radical, not like I redlined it or anything. The car started to overheat and I shut it down right away. After that I could drive it around for about 10 minutes or so and then it would heat up.

I pulled the Bosch water pump out today and the plastic impeller was broken and no longer turning with the shaft. It was still on the shaft at least, but no longer working. Now to see about getting my money back out of that pump. They have a 12 month warranty.

I just ordered the Hepu pump with the metal impeller. No more bosch pumps for me.

This related question was asked today:

Originally Posted by mjheinz

Has anyone had an experience using the Meyle water pump with the metal impellar sold from Bavauto.com ?

Thanks

The following question about an "UPDATED" BMW water pump was asked today:

Originally Posted by carlova78

I've just now come across the variety of water pumps with the metal impeller. Graf,Geba,Hepo, etc. But recently heard about the oem BMW water pump with updated to the composite impeller. Has anyone had experience with them?

I see two different ones here at Turner Motorsport...

1. http://www.turnermotorsport.com/p-10...ginal-bmw.aspx

2. http://www.turnermotorsport.com/p-39...-impeller.aspx

Here is the text for the first URL above (engine_m50_h20_pump.jpg):
> Now In: Engine Parts Water Pumps Water Pump - M52tu, M54 (Original BMW)

Water Pump - M52tu, M54 (Original BMW)

Part #: 11517527910 (11-51-7-527-910)
This Original BMW water pump is the latest updated design with a composite impeller. The composite material (similar to Kevlar) is much stronger than the problematic plastic impeller from past water pumps. And it's lighter than the aftermarket metal impellers so that means less strain on the bearing. For an OE/OEM replacement, we have found that this is the highest quality and longest lasting waterpump available.

This waterpump fits the following BMWs:
1999-2006 E46 3 series - 323i, 323Ci, 328i, 328Ci, 325i, 325Ci, 330i, 330Ci
1999-2003 E39 5 series - 528i (4/99+), 525i, 530i
1999-2002 Z3 Roadster/Coupe - Z3 2.8 (4/99+), Z3 2.5, Z3 3.0
2004+ X3 SAV - X3 2.5 & 3.0
2000-2006 X5 SAV - X5 3.0
2003-2005 Z4 Roadster/Coupe - Z4 2.5 & Z4 3.0
Price: $104.95 (USD)

And, here is the text for the second url above (cooling_e36_waterpump.jpg):
> Now In: Engine Parts Water Pumps Water Pump - M50, M52, M52TU, and M54 Engines with Metal Impeller

Water Pump - M50, M52, M52TU, and M54 Engines with Metal Impeller
Part #: 11511433828 (11-51-1-433-828)
The early M50/M52 engines had a serious weak point: the water pump. BMW originally used a plastic impeller in the waterpump. This would degrade over time and eventually break apart. Your car overheats immediately. This water pump is an updated one with a metal impeller. BMW has since released a water pump with a composte impeller that does not have the same issues and is just as reliable as the metal impeller version. But for piece of mind, the metal impeller is tough to beat.

This waterpump fits the following BMWs:
1999-2006 E46 BMW 323i, 323Ci, 328i, 328Ci, 325i, 325Ci, 325xi, 330i, 330Ci, 330xi
1997-2003 E39 BMW 528i, 525i, 530i
2004-2010 E83 BMW X3 2.5i & 3.0i
2000-2006 E53 BMW X5 3.0i
1997-2002 Z3 BMW Z3 2.8, Z3 2.5, Z3 3.0, MZ3 (S52)
2003-2005 E85 BMW Z4 2.5i & Z4 3.0i
Price: $59.95 (USD)

The screenshots for each waterpump advertisement are below:
- engine m50 h20 water pump.jpg
- cooling e36 water pump.jpg

Based on careful reading of the Turner Motorsports advertisements above, it seems they're implying that only the "early M50 & M52" engines 'may' have had plastic impellers - after which BMW quickly switched to composite impellers (note: the aftermarket has always had the metal impellers).

Assuming this statement by Turner Motorsports is true, then the only remaining question to answer the OP's question is the following:
QUESTION: What E39 models used the "early M50 and M52" engines? (i.e., these would have had plastic impellers originally, but which would have quickly switched to original composite impellers.)

got a new bosch with a plastic impeller and it went in less than a month. Had to throw the old one back on.

Stewart EMP is the only way to go. Do eeeeet!!!

I remember vividly about 2 years ago when I did the cooling overhaul, having the OEM WP compared to the Stewart EMP WP. It's like comparing the real deal with a toy. The difference is amazing.
Beside the stainless steel construnction, and very high quality materials, there's an important detail people often overlook: the beefed up bearing, which is very important if you use the OEM fan. That fan is not light, and the OEM sized waterpumps of any brand have the same small bearing rated for how many years? Does not matter if it's composite or plastic. If the impeller holds up, the bearing will go. There have been many reported WP bearing failures. The fan is heavy. The OEM sized waterpumps will hold longer if you use electrical fan.

For the record, this was asked today:

Originally Posted by Guam135i

I have a E39, 525i Touring. I replaced the expansion tank a few days ago after it cracked. Now I need to replace the water pump and since Im at it I will also replace the thermostat. The car has 61K miles.

The question is, is the Stewart warner WP worth he $195? or aftremarket with metal impeller at half the price? same question for the thermostat, OEM or replacement at half the price. Since I am at it would it be a good idea to replace the plastic WP pulley with an aluminum one?

I later plan to go to a zionville cooling system which does not include the WP or the Pulley at 80K miles

Thoughts on this is appreciated

Thanks after reading the posts on this thread the extra $100+ is worth the money if you consider the peace of mind and the cost of labor to replace the pump again. Thanks bluebee

Newbie question what is npg?

EMP Stewart has the best quality, if you have both in your hands, you will feel it right away, do it once and do it right

We have it for $175 if interested (free shipping 48 states)
http://www.bimmerzone.com/BMW_Perfor...STE-30330.html

Originally Posted by Guam135i

Newbie question what is npg?

I tried to put all the abbreviations used in the E39 forum over here:
- BMW E39 technoterms, acronyms, glossary, definitions slang, technical terms, abbreviations (1)
But, interestingly, even though I spent perhaps 100 hours on that one thread, I didn't list NPG unfortunately - so you wouldn't have found it there.

Luckily, the bestlinks has everything you need at the touch of a keyboard.
Typing /npg F3 in the best links, for example, netted this:
- What coolant to use (1) & all about propanol-based zero-pressure fluids like NPG+ (1) (2) (3) (4) (5)

Clicking on those five threads, we find out this about NPG:

Originally Posted by robertobaggio20

8. There's a company called Evans that sells a zero pressure cooling fluid called NPG+ (this is a brand name). Its basically 100% propanol which (if i'm not wrong) is an isomer of ethyl glycol, and is thus non-aqueous i.e. does not involve any water. .

Originally Posted by chiefwej

Well, I decided that if I run a zero pressure cooling system, I may not have to do that next cooling system overhaul. No pressure, no exploding radiator.

So I ordered a case of Evans NPG+ waterless coolant. Not cheap at about $120, but if it saves an overhaul............... The case was 4 gallons. It took 12 liters (or about 2 3/4 gallons) to fill the system. That leaves over a gallon for top-ups, since you can't add water or any other kind of coolant with Evans.

I fully drained the system, radiator, lower hose, block drains, and ran the heater pump to get it out of there. I must have got it all because Bentley says it holds 12 liters and that is exactly what I got in it. So everything must have been out and there can't be any air trapped in there. After the NPG+ fill I changed the 2 bar cap for a 1.4 bar one.

With a boiling point of 375 degrees there should never be any pressure in the system now.

Originally Posted by bobdmac

Bluebee, the short version is that the Evans boiling point of 375 F means that the cooling system doesn't need to be pressurized to keep the coolant from turning into vapor (boiling) before it gets to the radiator to cool back down to operating temperature.

As aloros said, this means that the vulnerable plastic parts and hoses don't have the added problem of handling elevated internal pressures.

So, given that I always try to put the answer to a question in the most likely place others will look for it, I'll add the following short description to the acronyms list:

NPG = A high boiling point (375°F) waterless (ethylene glycol based) coolant used to keep pressures in the cooling system close to zero bar (aka Evans NPG+)

I did my cooling overhaul today(Behr rad leaking at the seam, unsure of mileage), when I went with the Stewart pump, the one I pulled out of the car had a metal impeller with bmw and a part number stamped on it. Does anyone know if BMW makes pumps with metal impellers? I will post pics of the pump I pulled out.

edit:

Stewart on left, Old pump on right

I pulled out a stock BMW pump with 105K miles on it. It was a plastic impeller pump. I replaced it with a stock plastic impeller pump that now has 45K on it. BMW service does the same. Me thinks the lore of plastic impeller pumps from BMW self destructing is way over blown. If they were that bad, BMW would not use them for replacement. Too many pissed customers.

And I see from reading an earlier post from bluebee that what we call "plastic" may actually be composite.

"Based on careful reading of the Turner Motorsports advertisements above, it seems they're implying that only the "early M50 & M52" engines 'may' have had plastic impellers - after which BMW quickly switched to composite impellers (note: the aftermarket has always had the metal impellers)."

The original pump is made by INA. Replaced mine after 160K kms with worn bearing. Not leaking but bearing noisy. Now at 195K kms and no problems. I expect it to go another 160K kms.

RonR
99 528iT M52TU

For the record, the question of which brand came up again today over here:

Originally Posted by sodarock

Anyone using NAPA, auto zone water pumps their 540? I did put auto zones thrust arms on, but haven't drivenmuch cause of that good WI weather. Any opinions? It's gonna be under warranty. Thanks!

When I bought my car and not knowing that BMW likes special parts I did what I always do and go to Rockauto and start my list of parts.
I bought a URO water pump since it had the heart by it as to be one of the popular parts bought.
Has anyone used one of those pumps or know of experience as I have not installed yet.
TomK