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So today i've been told that the reason of leaking coolant fluid is my water pump(again). It is over 400$

The car is 535xi 2008 year. It's second time in a year that waterpump cracked.

I cant understand what were they thinking when they made plastic WP...

Now im thinking of getting Waterpump for N52 which is made of aluminium.

It is quite cheaper and i think it will last much longer.

My question is: What do you think? Will I be able to install Waterpump from N52 to N54 ?

As far as i can see from google search the only reasonable difference between them is in electric connector.

Below you can find sample pictures of each: N54 N52

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  • Is it going to physically fit? You might still have electrical incompatibilities, but you can give it a try and see.
    – rana
    Commented Oct 13, 2016 at 18:39
  • Is it going to fit physically is my main question :) giving it a try will cost additional 200(+50?)$ :)
    – Arif
    Commented Oct 13, 2016 at 18:51
  • Unless someone has tried it, I don't think there is a way to know. Check with your part store and see if they have a return policy in case it doesn't fit.
    – rana
    Commented Oct 13, 2016 at 19:06
  • In the pictures you posted, I can see the electrical connectors are in two different locations, how are you going to tackle this?
    – rana
    Commented Oct 13, 2016 at 19:08
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    If its less than a year old take it back threatening legal action. Paying over $400 for a part you would expect it to last many years.
    – Newbie Noob
    Commented Oct 13, 2016 at 19:56

6 Answers 6

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While I know you're asking about fit specifically, keep the following in mind, which I found on a forum discussing the differences between the N54 and N52:

Both engines have an electric coolant pump, but the N54 has a 400W pump (9000 l/h), while the N52 has a 200W pump (7000 l/h)

While the 528 is normally aspirated and probably doesn't need that extra cooling capacity, the 535 is turbocharged. There is a lot of extra heat associated with turbocharging and you could face overheating issues, which will cost you a lot more than a new water pump. It is a difference you should be aware of.

Traditionally water pump failure on these cars has been in the electronics, not the pump itself. You might want to look into why your pumps are cracking. Look for things that might be moving around but shouldn't. Did your mechanic over-tighten a clamp on the impeller housing? I know X3s used aluminum bolts for the engine mounts and those can break. I don't know about the 5s, but it's something to check. Also you should definitely inquire about a parts warranty. Less than 1 year of service life is shady even for the cheapest AutoZone parts.

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  • Thank you for your answer. I just went with original part which is much expensive(for just a pump)... Hope it will last longer
    – Arif
    Commented Oct 16, 2016 at 15:43
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In my travels, I haven't seen an aftermarket water pump listed for both the N52 and N54 engines. There are N54 water pumps with stronger materials though. You may wish to try one of those.

And as has been suggested by @Terry Gould, look into your warranty. Some parts do fail frequently, and the water pump on this engine is a known weakness, shop around (at a parts store, not the dealership) for a water pump from a more reputable parts manufacturer or one that uses better materials.

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In terms of physical fit:

  • you need a little more clearance at the back to accommodate the electrical connector with the aluminum pump.
  • the mounting points look identical
  • the coolant inlet and outlet hose connection points will not change

That said, something is not right. Why would a water pump fail so quickly again? If it is legitimately a manufacturing issue, like the S62's thermostat, I would consider getting the repair done at an authorized dealer so that the part is under warranty for a certain period after the fix.

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I have the same question as you here. My son's 2007 335i water pump went out about 6 months ago with a leaking pump. Now it's leaking again.
I can help with the why. There are several parts in the cooling system which are made of plastic that gets very brittle over time. My son's coolant level float which is in the pressurized reservoir was the first thing we noticed. The second was the coolant water fitting that broke about 2 months ago.
http://www.ebay.com/itm/BMW-335i-11537541992-OEM-WATER-HOSE-FITTING-REPLACEMENT-ALUMINUM-6061-/182218057115?hash=item2a6d0ae59b:g:m6MAAOSwuMFUdSD- These parts are slowly breaking off and circulating through the water coolant system, which in turns circulates through the water pump.
The impeller in the water pump that turns under the plastic piece that keeps cracking is metal. So the weakest link is the plastic piece. The impeller is withing only a few .001 of the plastic. This leaves no room for those plastic pieces which are circulating through the system. This is why you will see some of the youtube guys telling you to flush your system real good. We did this also, but I'm not sure you would flush every single piece out of your system without taking it all apart.
I'm trying to find out from a BMW Tech if the all aluminum water pump you show above is able to keep the twin turbo cars cooled or not.
If I find this information out I will post it here.

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I've replaced the water pump on my 14 535i. My two cents. It probably won't fit. You have to drop the sway bar and even then it's a tight fit. Also I don't think there is enough slack in the electrical connector to reach the plug on the water pump. The design is ok on these water pumps. My original lasted 80k miles which is what BMW expects. My 08 Acura lists the water pump as a replacement item during the 103k mile service. I'd say you got a bad part or a poor mechanic.

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to not be brittle, plastics contain a chemical called a plasticizer which keeps the plastic flexible. Heat over time drives the plasticizer out and the plastic becomes brittle and it breaks. I'd use an all metal pump.

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