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  1. #1

    BMW E46 Waterpump

    Folks, from what I understand the new water pumps from BMW use an improved composite impeller that is supposed to be top notch quality. After scavenging RealOEM I can see that the new part number went into effect 04/2003. Does this mean that post 04/03 cars have the new one. I personally would assume so. The reason why I ask is that this whole E46 cooling system i think has become a cash cow. Initially water pumps were failing early because of the plastic impeller so 60K became a preventative mark. With the composite impeller I don't know if 60 is where it should be.

    Any thoughts?

  2. #2
    Join Date
    Jan 1970
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    Redwood City, CA
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    It isn't that expensive by itself, I'd just replace it. If you DIY the whole kit it is not expensive really. You may or may not have the composite impeller pump (which isn't bulletproof); do you like to gamble?

    http://www.bimmerzone.com/BMW_Parts_...NG-MANUAL.html

    Just substitute the GRAF pump for OEM, I think it adds like $40. Not a bad deal.
    - Derek

  3. #3
    Join Date
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    Have been researching this myself lately as I'm getting within 10k miles of a coolant overhaul. BMW has supposedly improved both the water pump and the expansion tank, both of which seem to be the main targets of the preventative coolant overhaul.

    From what I've read, BMW stopped using the plastic/resin impellers in the water pumps some time ago, however, I can't find a definitive date that this occurred.

    That being said, I've also read that even with the composite or stainless impellers, pumps were experiencing a bearing failure at around 80K which is obviously just as devastating to the engine.

    I think you're on to something with the whole cash cow thing-- but I also think a lot of us love our cars too much to take the chance.

    Fwiw, my 325i (manufactured 6/03 iirc) went to almost 100k before I did the overhaul (bought it with 95K) and the only failure item was the thermostat. Original pump and expansion tank were still doing their job.

    Personally, at this point I'm gonna stick with the 60K mark until I see some more evidence to convince me that it's safe to do otherwise.

    Definitely interested to see what info others turn up, though.
    -Be yourself; everyone else is already taken.
    ZHP Pre-Ride Briefing

    2005 ZHP, Alcantara, Silver Cube, Nav, Sharked, BMW Perf Intake, BMW Perf CF Strut Brace, CF Valve/Fuel Rail Covers,
    Shadowline Grills, CF Splitters, Fog Light Inserts, Euro-mirrors, CDV Delete, Beisan vanos, GAS DISA, BP Coded

  4. #4
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    Ok-- some more digging shows that the pumps have gone through 3 generations of impellers.

    Original was metal impeller which was prone to bearing failure. 2nd gen was plastic impeller which was the impeller that was known for failure. BMW then went to 3rd gen which is the composite impeller which is supposedly not prone to either bearing or impeller failure. Of course, I can't find any dates to go along with those changes yet, but here are the P/Ns

    11-51-7-527-799 (metal) was superceded by:
    11-51-7-503-884 (plastic). This PN then was superceded by:
    11-51-7-527-910 (composite).

    The bearing failure info I found was in a bav auto blog from earlier this year, but according to them, BMW went from a plastic to a metal impeller, which seems to contradict all of the other info out there...

    Interesting discussion here
    Last edited by kayger12; 12-29-2010 at 07:21 AM.
    -Be yourself; everyone else is already taken.
    ZHP Pre-Ride Briefing

    2005 ZHP, Alcantara, Silver Cube, Nav, Sharked, BMW Perf Intake, BMW Perf CF Strut Brace, CF Valve/Fuel Rail Covers,
    Shadowline Grills, CF Splitters, Fog Light Inserts, Euro-mirrors, CDV Delete, Beisan vanos, GAS DISA, BP Coded

  5. #5
    Well, we all know fear sells. Take the radiator for example. Typically radiators don't just fail out of the blue, they start bleeding coolant slowly so it's something that should be inspected on a periodic basis. T-stats typically fail by staying open, meaning too cool and not too hot, often observed as the temp needle dropping at highway speeds. Expansion tank yes... it burst suddenly and sudden pump failures I can buy into as well. Hoses can go 80-90 miles easy. I at times feel the cooling issue on E46s has become kind of like the sub frame failure case, it's there but not in as large of quantities as people are lead to believe.

  6. #6
    p/n ... 910 went into effect 04/2003.

  7. #7
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    Moved to maintenance forum.

  8. #8
    Join Date
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    Quote Originally Posted by nk_zhp View Post
    p/n ... 910 went into effect 04/2003.
    Looks like we've all got the good pump then. Or at least the better of the pumps...
    -Be yourself; everyone else is already taken.
    ZHP Pre-Ride Briefing

    2005 ZHP, Alcantara, Silver Cube, Nav, Sharked, BMW Perf Intake, BMW Perf CF Strut Brace, CF Valve/Fuel Rail Covers,
    Shadowline Grills, CF Splitters, Fog Light Inserts, Euro-mirrors, CDV Delete, Beisan vanos, GAS DISA, BP Coded

  9. #9
    I call for a group fist pump (no pun intended)

    ...dude... I couldn't find this thread all of a sudden... then realized it moved.

  10. #10
    Join Date
    Jan 1970
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    Autozone.com
    Quote Originally Posted by nk_zhp View Post
    I call for a group fist pump (no pun intended)

    ...dude... I couldn't find this thread all of a sudden... then realized it moved.
    -Be yourself; everyone else is already taken.
    ZHP Pre-Ride Briefing

    2005 ZHP, Alcantara, Silver Cube, Nav, Sharked, BMW Perf Intake, BMW Perf CF Strut Brace, CF Valve/Fuel Rail Covers,
    Shadowline Grills, CF Splitters, Fog Light Inserts, Euro-mirrors, CDV Delete, Beisan vanos, GAS DISA, BP Coded

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