Advice for Cooling System Refresh for '06 3.0Si ?

[Z4Mariner]

I'm looking for advice on cooling system maintenance for N52 engined Z4’s. I have a 2006 3.0Si coupe with about 86K miles on it. No real concerns, but it is 16 years old. I will likely add another 2K miles before I store it for Winter. I plan to continue driving it daily, about 8 months a year, 10-12K miles per season. My 2005 E46 with an M54 engine seemed to need a lot of cooling system attention by 100K miles. I replaced most hoses, radiator, WP, T-stat, and radiator on that car around that mileage, but I waited until 167K miles to replace the heater hoses – barely in time because a plastic hose fitting into the cylinder head crumbled as I removed it. While my Z4 has low miles, it is a sixteen year old car, and my E46 was only ten years old when I did most of its cooling system. I would appreciate input on which things will really need replacing out of my "most everything" cooling parts list which appears below.

For certain I need to replace the "Mickey Mouse flange" coolant line. The WP & T-stat hoses are oily & soft. The Oil Cooler and Oil Filter Housing gaskets are due - when oil film is wiped off, it re-forms within a week. How necessary is the expansion tank mounting plate ?

Key Question: When the water pump and T-stat are out, can the Water Pump inlet pipe (BMW part number 11537516414) be easily removed from the block and reinstalled? The REIN replacement hose for the rubber part of that pipe, plus new gasket and O-ring will save over $100 vs new pipe. The BMW production hose clamp has no ears to remove the clamp from the hose onto the pipe, so removing it on a bench would be the easier thing.

_______Part Description________________Part Number__
BMW Electric Water Pump (Pierburg) . . . . . . . . . . 11517586925
BMW Engine Coolant Thermostat (Borg Warner) . . 11537549476
BMW Coolant Expansion Tank . . . . . . . . . . . . . . . 17117573751
Expansion Tank Mounting Plate . . . . . . . . . . . . . . 17112248408 ?
VNE coolant level sensor . . . . . . . . . . . . . . . . . . . 17137553919a
BMW Radiator Hose . . . . . . . . . . . . . . . . . . . . . . 17127545263
BMW Radiator Hose . . . . . . . . . . . . . . . . . . . . . . 17127537717
VNE coolant temperature sensor (for fan) . . . . . . ,13621433077
REIN T-Stat to WP Hose . . . . . . . . . . . . . . . . . . . 11537521049
Cylinder Head to T-stat Hose (REIN, Alum Flange) .11537545890
BMW Coolant Tank Recovery Hose . . . . . . . . . . . . 17127545277
BMW Heater Hose . . . . . . . . . . . . . . . . . . . . . . . .64216962464
BMW Heater Hose . . . . . . . . . . . . . . . . . . . . . . . .64216939219
BMW Oil Cooler Gasket . . . . . . . . . . . . . . . . . . . . 11428637820
BMW Oil Filter Housing Gasket . . . . . . . . . . . . . . .11428637821
REIN Coolant Hose, Oil Cooler to Pipe . . . . . . . . . .11537519494
Hose only for WP Coolant Feed Pipe . . . . . . . . . . . Rein CHE0496
BMW Water Pump Inlet Gasket . . . . . . . . . . . . . . .11537534880
BMW Engine Coolant Pipe O-Ring . . . . . . . . . . . . .11517514942
Radiator



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[Mr Tidy]

I can't help too much as I don't get too hands-on these days - I've discovered my limitations!

But I bought an E46 with the M54 engine on 80K miles and within a few months it suffered the typical "banana radiator".

I took it to my Indy who worked at a BMW main agent before setting up on his own and based on his recommendations it got a new radiator, expansion tank, cap and thermostat.

When the water pump died on my 2006 Coupe at 60K miles he just replaced the pump and thermostat, but he bought the pump from BMW so 6 years ago it cost just over £500.

So make sure you buy the OE Pierburg pump somewhere else!

Although given the age of our E86s replacing those hoses and O-rings should prevent future issues.

 

[Z4Mariner]

Thanks for quick response and reminder about the Pierburg pump !

And more info from another source: I have a friend who lives nearby and drives a 2006 3.0i roadster - his son is a BMW mechanic, and he just changed out my friend's oil cooler and oil filter housing gaskets, plus a few hoses. I asked my question about the water pump inlet pipe and its short little hose to the water pump.

His son said that he never removes the inlet pipe, because it's really hard to get it re-installed into the block. Instead, he takes advantage of the extra space when the water pump and T-stat are removed to get good access with a Dremel tool. He cuts the factory clamp on two sides to remove the short hose from the inlet pipe. REIN includes new clamps with the short hose that they sell, and the replacement spring clamp has "ears" to install / release it.

Since I'll do this while the car isn't being driven, I'll probably replace everything on my list, hoping that it will go another 80-90K miles without much worry.