Cylinder Head & Engine Warranty Policy
M&Y Auto Parts — Please read all terms and installation requirements carefully before installation. Failure to comply may void your warranty.
🛡 Warranty Coverage
We offer a 1-year warranty on labor and a 2-year warranty on parts from AFA Industries on long block engines, both from the date of purchase, unless otherwise stated at the time of sale. This warranty does not apply to cylinder heads.
All cylinder heads sold by M&Y are separately warranted against manufacturer defects only. This warranty does not cover damage resulting from improper installation, misuse, or failure to follow the installation requirements outlined below.
❌ What Is NOT Covered
M&Y is not responsible for damage resulting from any of the following:
- Timing issues
- Overheating
- Lack of lubrication
- Improper maintenance
- Unauthorized performance tunes or modifications
- Improper installation of cylinder heads
🔧 Cylinder Head Installation Requirements
The following installation standards must be met to maintain warranty coverage:
OEM torque specifications: All cylinder heads must be torqued to the proper OEM specifications. Failure to meet manufacturer torque requirements will void the warranty.
Valve bridges: We strongly recommend installing new valve bridges at the time of cylinder head replacement to ensure proper valve train operation and prevent premature wear.
Head bolts — Detroit Series 60: Brand new head bolts are required on all Detroit Series 60 models. Reusing head bolts on these engines is not permitted and will void the warranty.
Head bolts — Caterpillar & Cummins: We strongly recommend installing new head bolts on all Caterpillar and Cummins models. While not required, reusing head bolts on these platforms may compromise clamping force and head gasket integrity.
⚙️ Full Engine Overhaul Notice
If a brand new cylinder head is being installed as part of a complete engine overhaul, the engine must be properly broken in following our Heavy Duty Diesel Engine Break-In Procedure below. Failure to complete the break-in process may result in premature head gasket failure, improper ring seating, and voiding of the warranty.
Heavy Duty Diesel Engine Break-In Procedure
Required for all new and rebuilt engines. Failure to follow this procedure will void your warranty.
🔍 Why Proper Break-In Is Critical
Breaking in a new or rebuilt diesel engine allows the piston rings and cylinder walls to seat and seal properly under heat and load. Skipping or rushing this process can result in excessive oil consumption, power loss, poor fuel economy, and irreversible engine damage. These symptoms may not appear immediately but will worsen over time.
📚 Step-by-Step Break-In Procedure
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Initial startup: Start the engine and run at idle for no more than 10 minutes. Immediately inspect for oil leaks, coolant leaks, and verify proper oil pressure. Listen for any unusual noises and check the dashboard for warning indicators. |
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Avoid extended idling: Do not allow the engine to idle for prolonged periods. Excessive idling does not generate sufficient combustion pressure or heat to properly seat the piston rings and can cause cylinder wall glazing. |
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Use conventional oil only: Do not use synthetic motor oil during the break-in period. Use a conventional heavy-duty engine oil with an EP (extreme pressure) additive as specified by the engine manufacturer. |
Warranty terms are subject to change. For questions regarding your warranty or break-in procedure, contact M&Y directly before performing any repairs or modifications.