Coolant System Restoration N52

M

munchkincoupe

Member
My 2006 3.0si manual (95k miles) has now developed a coolant leak following the 1x overheating episode 2 weeks ago caused by green wire corrosion/failure stopping the fan from working. The car was stationery and running at the time to allow injector cleaner to run through. The fan is now fixed and running. The car runs fine but is losing coolant and I can see a fresh coolant fluid patch in the under tray beneath the expansion tank and radiator. When I get my hand right to the bottom there are drips of coolant coming off the bottom hose connection to the expansion tank and it doesn't feel like it has travelled along the radiator hose. Does this sound like a failure point for the tank or a hose seal?

It was refilled and bled properly following the overheating. I am having to top up the fluids approximately 4-500ml per day and covering max 15km with no overheating and no performance lag. I'm waiting for a gap with my mechanic to get pressure testing done.

My plan next year was to overhaul the cooling system but if they are going to have to drain the system and replace one part now and charge 2hrs+ labour I think might bite the bullet and just replace all the bits that go pop. My engine code is N52B30A

I was thinking:

electric water pump - Pierburg 702851200 - water pump
expansion tank - BMW 17117573751 - ? part manufacturer
radiator - BMW 17119071517 - ? part manufacturer
thermostat - BMW 17112249366 - ? part manufacturer

Can anyone with experience with this problem or parts please recommend parts brands, manufacturers or suppliers so that I don't need to remortgage the house!!!?

.... and are there any other bits that I would need to replace/order at the same time?

Thanks fellas
 
So ploughing through the posts on coolant system parts I should go for :

Pierburg Water Pump 702851200 - as they made the BMW part
Mahle Thermostat TM 14 97 - 4250192900633 - as they made the BMW part
BMW expansion tank - better quality than the aftermarkets

I was thinking I would go for a Mahle radiator but can anyone in the know tell me which I would need for my manual transmission with engine code N52B30A as there seems to be a few choices?

thanks for your help
 
That's what I choose for the thermostat and waterpump, too. I went for a Nissens expansion tank, but haven't got any longevity report to offer (not driven it since fitting).

I'd recommend grabbing some new o-rings too. Any connections you disturb will probably leak if you reuse the old o-ring

ebay.us

BMW Z4 2.2i 2.5i 2.5si 3.0 3.0si 3.2 Cooling System Radiator Hose O-Ring Kit | eBay UK

But don't waste money buying a new sensor or unnecessarily replacing hose assemblies, all of which can last well beyond 10 years/150,000 miles. These o-rings seal the BMW press & clip hose connections.
ebay.us
 
Hi, recently did the same pump and thermostat and also ordered the o rings from the US as above. Used a febi expansion tank and found it easier to take the tank with it's mounting bracket off and replace the new tank that way, rather than in situ.

Regards
 
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