The BEST Replacement Water Pump for the E46

Bosch water pumps = JUNK JUNK JUNK!!!!!!!!! Already tried a few of them on my cars!!!! Also Geba pumps while built well have a habbit of not enough flow at idle causing low heat complaints at idle..

just my 2 cents. But what does a greedy rip-off shop know....................

Pumps with plastic impeller:
Discontinued because of impeller shattering

Pumps with spot welded impeller:
Seen cases where impeller came apart, you don't want metal pieces inside the engine block.

Pumps with composite impeller (Current OEM):
Impeller seems to last but can't say the same for the bearing which likes to die at random mileage. If you have a mechanical fan connected to it be ready to have blades flying all over under the hood. OEM pumps also like to leak from the rubber gasket sometimes (and pls, it's torqued properly).

Having investigated all the available options (when my pump bearing failed) I chose to get the Stewart one. At least now I know that there's one thing less to break in my car.

So, IMHO the best replacement water pump for the E46 is the Stewart. If it's not an option, get the OEM and monitor it every once in a while

Originally Posted by delmarco

Everyone seems to be picking BOSCH? Why? Do the make the OEM ones that come in the cars at factory?

Bosch was known for its good quality parts but ever since the massive globalization efforts the amount of crap that comes out of Bosch is no less than any other manufacturer.

It's impressive how long it takes to taint a good brand name... what's more impressive is that it takes even longer to restore your image once it's down in the dumps.

Since the OEM pump changed from plastic to composite, the weak point is no longer the impeller, but the bearings. The new OEM composite impeller doesn't shatter like the old OEM plastic ones did.

So, your question should be more specific: Which one has the best bearings and bearing seals?
Anecdotal evidence suggests that the bearings on the aftermarket pumps aren't as reliable as the bearings on the OEM (reman) pumps. I know of no empirical evidence to back this up, though.

The Stewart pump, regardless of its "improved" pumping volume, has a lifetime warranty. That doesn't mean it'll last forever.

Originally Posted by jbeurotech

...

just my 2 cents. But what does a greedy rip-off shop know....................

Yeah... it's time you quit your shady job and did something else... like selling cars for example.

Originally Posted by nk_zhp

Yeah... it's time you quit your shady job and did something else... like selling cars for example.

yup!!! Or be a doctor and order needless tests and charge $20 for an aspirin...

Opps LOL sorry had to. i was just lloking at my last doctors bill when i posted this

Originally Posted by nathancarter

Since the OEM pump changed from plastic to composite, the weak point is no longer the impeller, but the bearings. The new OEM composite impeller doesn't shatter like the old OEM plastic ones did.

So, your question should be more specific: Which one has the best bearings and bearing seals?
Anecdotal evidence suggests that the bearings on the aftermarket pumps aren't as reliable as the bearings on the OEM (reman) pumps. I know of no empirical evidence to back this up, though.

The Stewart pump, regardless of its "improved" pumping volume, has a lifetime warranty. That doesn't mean it'll last forever.

Unfortunately to scientifically answer this question we would have to take a bunch of cars, equip them with all different pumps then run them trough an identical test cycle over a few years and then watch the sequence at which they fail. Needless to say this is an impossible task. Stewarts lifetime warranty is a marketing strategy and while that in itself might not indicate fail safe bearings, they do explicitly say that the bearing have been redesigned to be better and more durable.

On my M3 there is no tensioner. The tension of the belt is adjusted by moving the alternator angle away from the crank pulley. I found that the life of the bearing is directly proportional to how loose this belt is. So the key is to make it as loose as possible just before it start slipping at high RPMs. Clearly with E46s we don't have that choice so a bad tensioner pulley could also have a significant impact on this. One would hope that with age the tensioner will get looser and not tighter but I wonder if manufacturing tolerances cause slight differences in the actual tension imposed onto the water pump bearing.

Given the relatively low cost of the pump itself I think the best approach might be choosing the OEM-Composite pump and changing it every 60K.

No matter what some people say,there's no way i'll put an aftermarket WP in my car after 114k miles on the original one.

Originally Posted by tiloulou330i

No matter what some people say,there's no way i'll put an aftermarket WP in my car after 114k miles on the original one.

makes sense.

Originally Posted by nk_zhp

Given the relatively low cost of the pump itself I think the best approach might be choosing the OEM-Composite pump and changing it every 60K.

This is my plan. Well, every 75k anyway.

I know this thread is old but....

which WP did you end up buying Delmarco?

I'm looking into buying one soon.

Originally Posted by bimmerman11

I know this thread is old but....

which WP did you end up buying Delmarco?

I'm looking into buying one soon.

none yet. Back then I just decided to wait and save up for the Stewart which actually went up in price to $195 (the cheapest) since I started this thread.

My car just touched 70,000 miles on the odometer this week and and as if a sign from the E46 Gods my coolant expansion tank and my hoses just failed on me this week. I'm replacing the expansion tank and hoses actually right now as I'm writing this.

When done I will buy the stewart pump (@ $195) next month and also convert to an OEM Behr Electrical Fan ($180) like kpeng, nervous and solidjake did.

The OEM BMW Water Pumps are not cheap and costs $115+ at the Dealership. Plus my issue with the BMW Dealership sold pumps is that they have swiched between makers for the pumps they sell so today you could walk into BMW Of Manhattan and pay $130 for a water pump that could have GRAF stamped on it and next week you walk into a different BMW Dealership and pay $130 for a pump that has HEPA or BOSCH stamped on it.

So you never know what you are getting.

With a Stewart Pump you pay about $50 - $70 more and you know exactly what you are buying.

OE (Genuine BMW) would be my choice, but at the time of my cooling system rebuild, I used Graf. Been about 16,000 miles now with no issues.



OE Genuine BMW - $100.39 @ Tischer:



Hepu - $68.60 @ BMAPARTS.com:


Graf - $57.81 @ BMAPARTS.com:


Meyle - $48.22 @ BMAPARTS.com:


Stewart - $179.95 @ BMPDesign.com:

OEM


Olaf if you want an OEM let me know. A lot cheaper then what's listed here

Stewart ftw!!!!!!!!!!!

i have stewart pump and love it!

I went with the Stewart pump for the obvious benefits. Otherwise i would have gotten OEM bmw. The plastic impeller is no longer an issue and the bearings are likely to be better quality than the aftermarket options. Also it guarantees that you will have proper flow vs. other pumps that have had flow problems at idle like jbeurotech said.

Edit: The additional $30 shouldn't be that much of a concern when its a part to keep your engine from overheating. I'd rather spend a little extra to protect myself from larger repair costs and the headaches associated with them

Originally Posted by be-doubleyou

I went with the Stewart pump for the obvious benefits. Otherwise i would have gotten OEM bmw. The plastic impeller is no longer an issue and the bearings are likely to be better quality than the aftermarket options. Also it guarantees that you will have proper flow vs. other pumps that have had flow problems at idle like jbeurotech said.

Edit: The additional $30 shouldn't be that much of a concern when its a part to keep your engine from overheating. I'd rather spend a little extra to protect myself from larger repair costs and the headaches associated with them

plus the lifetime warranty that we have.. itl be our last water pump we by for this car

I just want us to be clear here, there's no such thing as an OEM pump. If there is, please advise as to the manufacturer who produces it for BMW and is marketed as such on various vendor's websitess. Don't mean to nitpick, but I want this to be clear so theres no confusion.

There is Genuine BMW or aftermarket.

I went through oembimmerparts and got what he claimed was OEM... It's a Soleri.

Maybe it was made by different manufacturers at times, I don't know. But it does have the composite impeller (sounds like metal when you thump it) like the BMW one. I know that unlike other parts, it's not marketed as OEM on different parts sites.

Incidentally, posted it when I did my overhaul, but the OE one in my car had a metal impeller and still looked perfect with no wobbles, no bearing sounds, nothing loose. I suspect it would go as long or almost as long as the Stewart. Someone said that was only made in 99-00 (or 00-01, one of those).

Anyway, if I were buying a new e46 I wanted to refresh and thought I'd keep it for many more years, I'd probably go with a Stewart.