What size bolt is a Honda engine mount?
There isn’t a single universal bolt size for Honda engine mounts. The correct size depends on the model, year and mounting point; you should check the vehicle’s service manual or OEM bolt kit for your specific car.
Why bolt size varies across Honda models
Engine mounts in Honda vehicles come in several configurations and mount locations. Different generations and engine types use different fasteners to secure the mount to the engine block, bracket, and subframe. Because of this variety, relying on a generic size can lead to improper fit, cross-threading or insufficient clamping force. Always confirm with model-specific documentation.
Before you consult the manual or start shopping for bolts, it helps to know the general range of sizes you might encounter. The following is a practical overview, with the understanding that exact specs must come from your car’s documentation.
Common bolt size ranges you may encounter
Engine mounting hardware typically uses one of a few standard metric diameters. The following ranges cover most Honda applications, but exact lengths and thread pitches vary by model and year.
- M8 bolts (diameter 8 mm)
- M10 bolts (diameter 10 mm)
- M12 bolts (diameter 12 mm)
Thread pitch and bolt length are not universal and depend on the mounting point. Common thread pitches include approximately 1.25, 1.5, and 1.75, but you should verify for your specific model.
How to identify the correct bolt size for your Honda
To determine the exact size for your model, follow these steps:
- Identify the mounting point you are dealing with (engine-to-block, bracket-to-engine, or subframe connection).
- Examine the bolt you are replacing or measure its diameter with calipers if you can access it in place.
- Determine the thread pitch by using a thread gauge or by matching the thread with a known bolt from a reputable fastener kit.
- Measure the bolt length from under the head to the end, accounting for any shoulder or seating surfaces.
- Consult the factory service manual or an OEM bolt kit to confirm the exact specifications, including any required torque and whether threadlocker is specified.
- Install with new, OEM- or high-quality replacement bolts and torque to the manufacturer’s specification.
Following these steps will help you confirm the correct size and avoid installation issues that can compromise engine mounting integrity.
Safety and installation tips for engine mount bolts
Beyond size, proper installation practices are essential to ensure long-term reliability and safety. The following guidelines apply across Honda engines and mounting points.
- Use new, OEM-quality bolts rather than reusing old fasteners, which can lose clamping force.
- Ensure you use the correct grade bolts as specified by Honda (often higher-strength grades for engine mounts) and follow the recommended torque values precisely.
- Check whether the manual requires threadlocker or anti-seize, and apply only as directed by the manufacturer.
- Clean bolt threads and mounting surfaces before installation to prevent uneven clamping or cross-threading.
- Support the engine properly during work to avoid shifting loads that could damage mounts or adjacent components.
Adhering to these practices helps maintain engine alignment and reduces the risk of mount failure.
Summary
In short, there is no one-size-fits-all bolt for Honda engine mounts. Sizes commonly fall within the M8–M12 range, but the exact diameter, thread pitch, and length depend on the specific model and mounting point. Always verify with the vehicle’s service manual or OEM hardware kit, use fresh high-quality bolts, and torque them to the manufacturer’s specifications. By following model-specific guidelines, you’ll ensure a secure, reliable engine mounting setup.
