Oil in your coolant? Before you pull the cylinder head, check the oil cooler. The 373-4830 (ZTSE6063) test plates are the only way to confirm a cooler failure on CAT CT660 engines. The Challenge of Cross-Contamination On the CAT CT11, CT13, and CT15 platforms, an internal oil cooler leak often mimics the symptoms of a blown head gasket or a cracked block. Without the ability to isolate the cooler, many shops perform unnecessary, expensive engine teardowns. The 373-4830 test plates allow you to seal the cooler ports and apply pressure directly to the core, providing an undeniable "pass/fail" result in minutes. Targeted Diagnostics – Specifically designed for the CAT CT660 truck platform and shared Navistar MaxxForce engines. Seal and Test – Creates a high-pressure seal to find micro-cracks that only leak under operating temperature and pressure. Avoid Costly Errors – Confirms whether the oil cooler is the source of contamination before you move to the engine block. Cross-Platform Use – Works seamlessly with CT11, CT13, and CT15 engines as well as MaxxForce 11, 13, and 15 models. Professional Grade – Heavy-duty construction ensures these plates remain a permanent fixture in your diagnostic kit. Precision Testing for Heavy-Duty Engines The 373-4830 Oil Cooler Test Plates are essential for any shop servicing on-highway CAT engines. Isolate the failure, save your customer money, and increase your shop’s turnaround time. Verify the Cooler. Save the Engine. Buy 373-4830 Plates – $85.00