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D4656-98 – Standard Test Method Technical Guide
📐 Composition and General Requirements
This specification, D 4656-98, covers prediluted aqueous ethylene glycol base engine coolant with a minimum of 50 volume % ethylene glycol. It is formulated for use in automobiles and light-duty vehicles, providing effective cooling system operation in both summer and winter without further dilution. The coolant must include suitable corrosion inhibitors, dye, and a foam suppressor to ensure performance and stability.
| 🟦 Property | 📏 Requirement | 📐 Test Method |
|---|---|---|
| Ethylene Glycol Content | 50 volume % minimum | D 5931 or D 1122 |
| Freezing Point | Below -34°F (-37°C) | D 1177 |
| Boiling Point | Above 226°F (108°C) | D 1120 |
| pH | 8.0 – 11.0 | D 1287 |
| Reserve Alkalinity | 10 mL minimum | D 1121 |
💡 Tip: This coolant is ready to use without dilution. Always check the specific requirements of your vehicle’s cooling system before application.
⚙️ Testing and Performance Specifications
To ensure reliability, the coolant must pass several performance tests. Corrosion protection is evaluated via the glassware corrosion test (D 1384), which assesses weight loss on metal specimens. Foaming tendencies are limited to prevent overheating. The coolant also undergoes simulated service testing (D 2570) to replicate real-world conditions.
| 🟦 Component | 📏 Maximum Weight Loss (mg/cm²) | 🎯 Test Standard |
|---|---|---|
| Copper | 10 | D 1384 |
| Solder | 30 | D 1384 |
| Brass | 10 | D 1384 |
| Steel | 10 | D 1384 |
| Cast Iron | 10 | D 1384 |
| Aluminum | 30 | D 1384 |
Additionally, the coolant must demonstrate no significant foaming in the D 1881 test and protect aluminum in the D 2809 cavitation test.
📊 Key Measured Properties
Other critical properties include density, ash content, and chloride levels. These are measured using methods like D 1122, D 1119, and D 3634 respectively. Compliance ensures the coolant meets safety and performance benchmarks.
⚠️ Warning: Using this coolant in heavy-duty engines may not be appropriate unless specified. Refer to D 5345 for heavy-duty requirements.
❓ Frequently Asked Questions
🔍 What is the difference between D 4656 and D 3306?
D 4656 covers prediluted coolant (50% min ethylene glycol) ready for use, while D 3306 covers coolant concentrate that requires dilution before use.
💡 Can this coolant be used in all vehicles?
It is intended for automobiles and light-duty service. For heavy-duty engines, refer to specification D 5345.
⚡ What is the boiling point protection?
The coolant has a boiling point above 226°F (108°C), providing effective cooling in summer conditions.
📌 How often should the coolant be tested?
Regular testing of freezing point and pH is recommended to ensure continued protection. Follow the vehicle manufacturer’s schedule.