Cooling System Refresh

Although I received some maintenance documentation when I purchased the car, there was no mention of any water pump or radiator replacement and the cooling system appeared to mostly be the original 15 year old items, so it was time for a refresh.

Given the condition of the fins on the engine side of the radiator, the front of the engine had been worked on at some point:

Original Radiator Engine Side.png

I keep a stock of large flat sheets of cardboard around, mostly recycled shipping boxes; a radiator-sized chunk of cardboard tucked in on the engine side of the radiator during the job would have prevented such damage.

Lots of interesting debris captured between the A/C condenser and the front of the radiator:

Original Radiator A-C Condenser Side.png

Some of the other cooling system and belt drive items that were replaced during this episode:

Old Parts.png

The water pump had been replaced with a steel impeller BMW pump, which looked nearly new, and might explain the radiator fin tweakage.  I already had a Stewart pump on hand for the job. Anybody need a water pump?

Comparison of a Stewart pump with a standard BMW water pump:

Stewart vs. Standard Water Pump.png

Given the stories I have heard and read of BMW plastic fans shedding blades and perforating hoods and cooling systems, I'm going to try the mechanical fan delete option that other Z3 owners have used with success; I'm skeptical.   

I treated the Stewart pump to a Fan Delete nut:

Stewart Water Pump Installed.png

The sketchy phenolic OEM thermostat housing was replaced with a surprisingly nice $15 aluminum casting made by Üro; I went with a Üro aluminum water pump pulley as well.  I know people have had issues with some aftermarket aluminum T-stat housings that either developed hairline cracks or had less than flat gasket surfaces; I carefully inspected the Üro casting and lapped the gasket surface on a surface plate to verify the flatness. I suppose there could be an internal casting flaw, but when it comes to cooling system hard parts I'm an old school kinda guy; in most cases aluminum trumps plastic. I was tempted to go with a racer-oriented all-aluminum radiator and expansion tank, but the OEM BMW radiators and expansion tanks seem to hold up pretty well; the phenolic T-stat housing just seemed wrong and had to go. Less than perfect logic I know:

Ready for shroud and hose installation:

Ready for Hoses.png

Brass Air Bleed Screw:

Brass Bleed Screw.png

Sorted!

Cooling System Refresh Completed!

Cooling System Refresh Completed!

 
Genuine BMW Coolant

Genuine BMW Coolant

 
Expansion Tank

Expansion Tank

 
Expansion Tank Cap

Expansion Tank Cap

 
Z3  S52 / M52 Radiator

Z3  S52 / M52 Radiator

 
S52 / M52 Upper Radiator Hose

S52 / M52 Upper Radiator Hose

 
S52 / M52 Lower Radiator Hose

S52 / M52 Lower Radiator Hose

 
Expansion Tank Lower Hose

Expansion Tank Lower Hose

 
Expansion Tank Upper Hose

Expansion Tank Upper Hose

 
S52 / M52  Cooling System Hose and Tube Kit

S52 / M52  Cooling System Hose and Tube Kit

 
Upper Radiator Brackets

Upper Radiator Brackets

 
Stewart Performance Coolant Pump

Stewart Performance Coolant Pump

 
Standard Coolant Pump

Standard Coolant Pump

 
Aluminum Water Pump Pulley

Aluminum Water Pump Pulley

 
Aluminum Thermostat Housing

Aluminum Thermostat Housing

 
OEM 88°C Thermostat

OEM 88°C Thermostat

 
Fan Blade

Fan Blade

 
Brass Air Bleed Screw

Brass Air Bleed Screw

 
Fan Shroud Expanding Rivets

Fan Shroud Expanding Rivets

 
Hydraulic Belt Tensioner Pulley

Hydraulic Belt Tensioner Pulley

 
Accessory Belt

Accessory Belt

 
Deflection Pulley

Deflection Pulley

 
A/C Belt Adjusting Pulley

A/C Belt Adjusting Pulley