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BMW 5 Series 525i E34 Thermostat Engine Code -M20 B25 89-90
  • BMW 5 Series 525i E34 Thermostat Engine Code -M20 B25 89-90

BMW 5 Series 525i E34 Thermostat Engine Code -M20 B25 89-90

TM5145
BMW

BMW 5 Series 525i (E34) Thermostat ( Engine Code -M20 B25 ) 89-90

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R195.00
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Description

BMW 5 Series 525i E34 Thermostat Engine Code -M20 B25 89-90

Thermostats & Thermostat Housings — OEM-Spec Temperature Control

Precise temperature control is the backbone of modern engines. This OEM-spec component (thermostat or integrated housing, depending on the application) restores correct warm-up behaviour, stabilises operating temperature, and protects against overheating in South African conditions.

Why replace the thermostat / housing

  • Restores correct warm-up strategy and stable operating temperatures
  • Prevents overheating, detonation and oil breakdown under SA heat
  • Protects turbochargers, head gasket and emissions systems
  • OEM-aligned design for fitment, sealing and sensor compatibility

Component overview

Thermostat (wax / electronic)
  • Controls coolant flow between engine and radiator
  • Wax-type opens by temperature; electronic units add ECU control
  • Failure modes: stuck open (runs cold), stuck closed (overheats)
Thermostat housing / module
  • Integrated unit with thermostat, O-rings, sensors and routing channels
  • Material: polymer or alloy; each requires correct torque and sealing
  • Failure modes: leaks, warping, cracked spigots, sensor faults

Common symptoms

  • Temperature gauge drops at speed but climbs in traffic (stuck open)
  • Overheating warnings, boiling sounds, or coolant push (stuck closed)
  • Coolant residue or staining around housing joints and hose unions
  • Heater weak at idle, improves with revs (air or poor flow)
  • ECU codes for thermostat heater / temp correlation (electronic units)

What’s included

  • Thermostat or thermostat-housing module matched to the listed application
  • Seals/O-rings where applicable

Images are for illustration. Confirm by OE/part number, engine code and connector type. Contact us with your VIN for fitment support.

Installation best practice

  • Flush system and refill with OEM-approved coolant and deionised water
  • Clean mating faces; replace O-rings; torque fasteners to spec
  • Follow the bleed procedure to remove air pockets (critical)
  • For electronic units: check connector condition and route loom correctly

FAQs

Is this a thermostat or a complete housing?
It matches the vehicle application listed. Some models use a standalone thermostat, others use an integrated housing/module.

Can I replace an electronic thermostat with a basic wax unit?
No. Vehicles calibrated for electronic control need ECU-assisted response for warm-up and load changes.

Do I need new coolant?
Yes. Wrong or contaminated coolant causes deposits, poor valve response and leaks. Use OEM-approved coolant with deionised water.

Should I replace the thermostat when fitting a new water pump?
Recommended on higher-mileage cars to stabilise temperatures and protect the head gasket.

How do I confirm fitment?
Match by VIN or OE number (opening temperature, connector style, housing layout). We can confirm before purchase.

Warranty & important notes

  • 12-month warranty against manufacturing defects
  • Warranty requires correct coolant, proper bleeding and torque procedures
  • Mixing coolant types or using tap water may void warranty
Need help confirming fitment? WhatsApp 069 777 2 777 or call 010 970 6009. Have your VIN ready for the fastest assistance.
Product Details
BMW
TM5145
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