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Automatic Transmission Oil Cooler
This photo shows the same type of part you'll receive. Since each used part has its own wear and scratches, yours may look slightly different. Check the product notes for details about the condition of this specific part.

2003 - 2005 BMW Z4 Automatic Transmission Cooler (OEM)

Only 1 left in stock
$97.95

ℹ️ Product Notes

This is a used part. This is an extra cooler (auxiliary) for your transmission oil. It is designed for vehicles that have a 2.5 Liter engine.

Fits automatic transmission models only. This auxiliary heat exchanger mounts to the radiator. Check your old part for matching connectors before buying.
Condition: Excellent (A)
Like new, minimal to no wear
76,844 miles
Odometer reading when part was removed
See Other BMW Z4 Automatic Transmission Oil Coolers
SKU #
7709521-50I1MB.414

Why Buy Used OEM Parts?

✓ Quality-Verified: Every used OEM part we sell has been professionally inspected and tested to ensure it meets our quality standards. While it may show some cosmetic wear from previous use, it's fully functional and ready to install.

✓ Original Equipment: This is a genuine OEM (Original Equipment Manufacturer) part - the exact same part that came with your vehicle from the factory. It's designed specifically for your make and model, ensuring perfect fitment and performance.

✓ Works Like New: Despite some visual wear, this part will perform just as well as a brand new one. The internal components and functionality are intact, giving you the same reliability you'd expect from OEM quality.

✓ Significant Savings: Save 50-80% compared to buying new! Used OEM parts offer exceptional value - you get factory quality at a fraction of the cost. It's the smart choice for budget-conscious vehicle owners who won't compromise on quality.

✓ Risk-Free Purchase: We stand behind our used parts with a generous 6-month warranty, 30-day returns, and 100% money-back guarantee. If it doesn't work out for any reason, simply return it for a full refund. You have nothing to lose!

🛡️ 30-Day Returns + 6-Month Warranty - Buy with Confidence!

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Vehicle Fitment Guide

This part fits the following vehicles:

BMW
Z4 2003-2005 (tapclick to expand)(tapclick to hide)
Swipe left/right to see more info
SubmodelSUB-
MODEL		 Body Style Years Engine Attributes
2.5i Convertible 2003 - 2005 L6 2.5L RWD | Automatic
3.0i Convertible 2003 - 2005 L6 3.0L RWD | Automatic

⚠️ Important: Please verify your vehicle's year, make, model, and specifications before ordering. If you're unsure about fitment, contact our customer service team for assistance.

Policies

Shipping & Handling

  • Standard shipping: 3-7 business days via UPS Ground
  • Parts are carefully packaged to prevent damage during transit

Returns (30 Days)

We accept returns within 30 days of delivery for this part.

  • Defective parts: We will replace the part or issue a refund at our discretion
  • Electronic parts: Must be returned with the sealed inspection bag unopened. The clear bag allows full visual inspection before opening. Once opened, electronic parts can only be exchanged for a replacement if defective — no refunds
  • Programming: "Needs to be programmed to my vehicle" is not a valid return reason. Many modules require dealer programming — we're happy to help connect you with resources if your dealer says it's not programmable
  • Return shipping: We cover return shipping as part of our 100% money-back guarantee
  • Parts must be returned in original packaging and unmodified condition
  • Poorly packaged returns that arrive damaged will not be credited

6-Month Warranty

All used parts include a 6-month warranty from the date of purchase.

  • If your part fails within 6 months, we will send a replacement
  • Refunds are only issued if we cannot provide a suitable replacement
  • Warranty covers defects — not installation errors, misuse, or damage after installation

Note: Warranty is for replacement, not refund. A part failing on day 80? We'll replace it. But the return window for refunds is 30 days.

Damaged in Shipping?

If your part arrives damaged:

  • Stop immediately — do not install the part
  • Keep all original packaging and boxes
  • Take clear photos of the damage and packaging
  • Contact us within 48 hours of delivery

We will handle the carrier claim. You are not responsible for shipping damage — we just need your help documenting it.

Order Cancellation

Orders can be cancelled before shipment for a full refund. Once shipped, cancellations follow our return policy.

Symptoms & Diagnosis

Warning signs the Automatic Transmission Cooler is failing:

  • Transmission fluid leaks near the cooler. Look for red or brown fluid.
  • Overheating transmission. Your car may shift roughly or not at all.
  • Transmission slipping. The engine revs but the car doesn't accelerate properly.
  • Unusual noises from the transmission.
  • Check engine light. A code related to transmission temperature may be stored.

How to test if this part is the problem:

  1. Check the fluid level: Low fluid can cause similar symptoms.
  2. Inspect the cooler: Look for physical damage, leaks, or corrosion.
  3. Pressure test the cooler: A professional can test the cooler for leaks under pressure.
  4. Check the transmission fluid temperature: Use a scan tool to monitor the temperature while driving. Overheating suggests a cooling problem.
  5. Bypass the cooler: Temporarily bypass the cooler to see if the symptoms improve. Important: Only do this for a short test period, as it can damage the transmission.

Common failure causes for this part:

  • Corrosion from road salt and debris.
  • Physical damage from accidents or impacts.
  • Clogging from debris or contaminated transmission fluid.
  • Internal leaks due to age and wear.
  • Overheating due to other transmission problems.

Buyer's Checklist

What to look for when buying this part:

  • Compatibility with your specific BMW model year.
  • Condition of the cooler (if buying used or refurbished).
  • Warranty offered by the seller.
  • Price compared to other options.
  • Seller's reputation and return policy.

Quality indicators for the available options:

FeatureUsed OEMRefurbished OEMNew Aftermarket
Original QualityYesYesPotentially
PriceLowestMid-RangeMid-Range to High
WarrantyVariesOften IncludedOften Included
TestingInspected & TestedRebuilt & TestedNew

What's typically included with the part:

  • The automatic transmission cooler itself.
  • Mounting brackets (sometimes).
  • Fittings or connectors (sometimes).
  • Seals or gaskets (sometimes).

Installation Overview

Difficulty level and estimated time:

  • Moderate. Requires some mechanical knowledge.
  • Estimated time: 1-3 hours.

Special tools needed (if any):

  • Socket set
  • Wrench set
  • Screwdrivers
  • Pliers
  • Torque wrench
  • Transmission fluid (compatible with your BMW)
  • Drain pan
  • Hose clamps (if needed)

Critical steps and tips:

  1. Disconnect the battery: Prevents electrical shorts.
  2. Drain the transmission fluid: Use a drain pan to catch the fluid.
  3. Disconnect the cooler lines: Be careful not to damage the lines.
  4. Remove the old cooler: Unbolt or unclip the cooler from its mounting location.
  5. Install the new cooler: Securely mount the new cooler.
  6. Connect the cooler lines: Ensure the connections are tight and leak-free.
  7. Refill the transmission fluid: Use the correct type and amount of fluid.
  8. Check for leaks: Start the engine and inspect for leaks around the cooler and lines.

Whether DIY is recommended or professional installation is better:

  • DIY is possible for mechanically inclined individuals.
  • Professional installation is recommended if you are not comfortable working on your car's transmission system.

Buying Options

Compare: Used OEM, Refurbished OEM, New Aftermarket

OptionProsCons
Used OEMLowest price, genuine factory part, tested and inspectedMay have some wear and tear, shorter warranty
Refurbished OEMRestored to like-new condition, genuine factory part, often includes a warrantyHigher price than used, may not be as reliable as new
New AftermarketBrand new, often less expensive than new OEMQuality may vary, may not fit as well as OEM

Used OEM:

  • Best value for money.
  • Genuine factory parts, ensuring proper fit and function.
  • Tested and inspected to meet quality standards.
  • Significantly lower prices than new options.

Refurbished OEM:

  • Factory parts professionally restored to like-new condition.
  • Rebuilt with new components as needed.
  • Offers a balance of quality and value.

New Aftermarket:

  • Brand new, third-party parts built to OE specifications.
  • Can be a cost-effective alternative to OEM parts.
  • Quality may vary depending on the manufacturer.

Typical Lifespan

How long this part normally lasts:

  • 75,000 - 150,000 miles.

Factors that affect longevity:

  • Driving conditions (stop-and-go traffic, towing).
  • Maintenance habits (fluid changes).
  • Climate (extreme heat or cold).
  • Quality of the part.

Price Ranges

Budget vs mid-range vs premium options:

  • Used OEM: $50 - $150
  • Refurbished OEM: $100 - $250
  • New Aftermarket: $75 - $300

Labor cost considerations if applicable:

  • Professional installation: $150 - $400

Total job cost estimates:

  • DIY (Used OEM): $50 - $150 (plus fluid)
  • DIY (New Aftermarket): $75 - $300 (plus fluid)
  • Professional Installation (Used OEM): $200 - $550 (parts and labor)
  • Professional Installation (New Aftermarket): $225 - $700 (parts and labor)

Vehicle-Specific Notes

Known issues for this vehicle's system related to this part:

  • Some models are prone to leaks at the cooler line connections.
  • Overheating can be a common problem in certain driving conditions.
  • Check for any Technical Service Bulletins (TSBs) related to transmission cooling issues.

Any TSBs or common complaints:

  • Research common complaints about transmission overheating for your specific model year.
  • Check for TSBs related to transmission cooling system issues.

Verification After Install

How to confirm proper operation:

  • Check the transmission fluid level.
  • Monitor the transmission fluid temperature.
  • Check for leaks around the cooler and lines.
  • Test drive the vehicle to ensure smooth shifting.

What to look/listen for to verify it's working correctly:

  • No leaks.
  • Normal transmission fluid temperature.
  • Smooth and consistent shifting.
  • No unusual noises from the transmission.

FAQ

Q: How do I know if my transmission cooler is leaking?
A: Look for red or brown fluid near the cooler or on the ground underneath your car. Also, check your transmission fluid level. If it's low, that could be a sign of a leak.

Q: Can I drive my car if the transmission cooler is leaking?
A: It's not recommended. A leaking cooler can cause your transmission to overheat, which can lead to serious damage.

Q: How often should I change my transmission fluid?
A: Refer to your BMW's owner's manual for the recommended service interval. Generally, it's every 30,000 to 60,000 miles, but it can vary.

Q: Is it hard to replace a transmission cooler myself?
A: It requires some mechanical knowledge and tools. If you're not comfortable working on your car's transmission system, it's best to have a professional do it.

Q: What kind of transmission fluid do I need for my BMW?
A: Use the type of fluid specified in your BMW's owner's manual. Using the wrong fluid can damage your transmission.

Part Specifications

OEM Part Numbers:

  • BMW: 17221436258, 17227505826, 7505826

Fits Years: 2003 2004 2005

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