Product Overview
The Dorman 674-250 Driver Side Exhaust Manifold Kit is engineered to provide a direct replacement for the original exhaust manifold on specific Chevrolet, GMC, and Isuzu vehicle models. This kit includes all necessary gaskets and hardware for a complete and reliable repair, ensuring proper fit and function.
This component is crucial for directing hot combustion gases from the engine into the exhaust system. It is designed to withstand extreme heat cycles, which can cause cracks and leaks in lesser quality manifolds, leading to emissions test failures and reduced engine performance.
The Dorman 674-250 is manufactured to original equipment (OE) specifications, ensuring a perfect installation and reliable performance. It is also available in CARB compliant applications for vehicles requiring the highest emission standards.
Vehicle Compatibility
This exhaust manifold kit is compatible with the following vehicle models. Please verify fitment for your specific vehicle trim using the manufacturer's garage tool or by cross-referencing part numbers.
- Chevrolet G30: 1991, 1992, 1993, 1994, 1995, 1996
- Chevrolet P20: 1989
- Chevrolet P30: 1989, 1990, 1991, 1992, 1993, 1994, 1995
- Chevrolet W3500 Tiltmaster: 1995
- Chevrolet W4500 Tiltmaster: 1993, 1994, 1995
- GMC G3500: 1991, 1992, 1993, 1994, 1995, 1996
- GMC P2500: 1989
- GMC P3500: 1989, 1990, 1991, 1992, 1993, 1994, 1995
- GMC W3500 Forward: 1995
- Isuzu NPR: 1993, 1994, 1995
Included Components
The Dorman 674-250 kit provides all necessary components for a complete installation:
- Driver Side Exhaust Manifold (Cast Iron)
- Required Gaskets
- Downpipe Hardware (bolts, nuts, studs)
Installation Guidelines
Installation of an exhaust manifold requires mechanical expertise and appropriate tools. If you are not comfortable performing this repair, it is recommended to seek professional assistance.
- Preparation: Ensure the vehicle is cooled down. Disconnect the battery. Safely lift and support the vehicle.
- Removal of Old Manifold:
- Locate the driver side exhaust manifold.
- Disconnect any sensors or pipes attached to the manifold.
- Remove the bolts and nuts securing the manifold to the engine cylinder head and the downpipe.
- Carefully remove the old manifold and gaskets. Inspect the cylinder head surface for damage or corrosion.
- Installation of New Manifold:
- Clean the mating surfaces on the cylinder head and downpipe thoroughly.
- Position the new gaskets onto the cylinder head studs.
- Carefully place the new Dorman 674-250 exhaust manifold onto the studs.
- Install the new nuts and bolts, tightening them finger-tight initially.
- Connect the manifold to the downpipe using the provided hardware and new gasket.
- Torque all fasteners to the vehicle manufacturer's specifications, following the recommended tightening sequence (typically from the center outwards).
- Reconnect any sensors or pipes that were detached.
- Final Steps: Lower the vehicle, reconnect the battery. Start the engine and check for exhaust leaks.
Note: Always refer to your vehicle's specific service manual for detailed torque specifications and procedures.
Operating Considerations
Once installed, the Dorman 674-250 exhaust manifold operates as part of your vehicle's exhaust system. Proper function is essential for engine performance and emissions control.
- Engine Noise: A properly installed manifold should not produce excessive exhaust noise. Any new or unusual noises may indicate a leak.
- Emissions: This manifold is designed to meet or exceed emissions standards. If your vehicle has an integrated catalytic converter (not applicable to this specific model, but common in other Dorman manifolds), it will be CARB compliant where required.
- Heat Management: Exhaust manifolds operate at very high temperatures. Avoid contact with the manifold during and immediately after engine operation.
Maintenance
Exhaust manifolds generally require minimal maintenance beyond ensuring proper installation and checking for leaks. Regular vehicle inspections should include the exhaust system.
- Periodic Inspection: Visually inspect the manifold and its connections during routine oil changes or vehicle maintenance. Look for signs of cracks, rust, or loose fasteners.
- Leak Detection: Listen for hissing or ticking sounds from the engine bay, especially when the engine is cold. These can indicate an exhaust leak.
- Fastener Torque: Over time, exhaust fasteners can loosen due to heat cycles. Re-torqueing fasteners to specification if a leak is suspected can sometimes resolve minor issues.
Troubleshooting
| Symptom | Possible Cause | Solution |
|---|---|---|
| Loud exhaust noise from engine bay | Exhaust leak (cracked manifold, failed gasket, loose fasteners) | Inspect manifold for cracks. Check gasket integrity. Re-torque fasteners. Replace damaged components. |
| Exhaust smell in cabin | Exhaust leak allowing fumes into ventilation system | Identify and repair exhaust leak immediately. Ensure proper cabin air filtration. |
| Reduced engine performance or fuel economy | Significant exhaust leak affecting exhaust gas flow and sensor readings | Diagnose and repair exhaust leak. Check oxygen sensor function if applicable. |
| Check Engine Light (CEL) illuminated | Exhaust leak affecting oxygen sensor readings, or catalytic converter issue (if integrated) | Retrieve diagnostic trouble codes (DTCs). Address exhaust leaks or catalytic converter issues as indicated by codes. |
If troubleshooting steps do not resolve the issue, consult a qualified automotive technician.
Specifications
- Model Number: 674-250
- Brand: Dorman
- Material: Cast Iron
- Installation Type: Bolt-On
- Automotive Fit Type: Universal Fit (for specified models)
- Item Weight: Approximately 15.57 pounds
- Product Dimensions: Approximately 20.38 x 9.63 x 5.13 inches
- Bolt Pattern (Number of Holes): 6
- Color: Gray
- OEM Part Numbers: 101101; 10166143; 8-10166-143-0
- UPC: 194950273864, 019495027386
Warranty Information
Dorman conventional exhaust manifolds are backed by a lifetime warranty against defects. Manifold converters (if applicable to a specific Dorman product) are guaranteed for five years or 50,000 miles. For specific warranty details and claims, please refer to the official Dorman warranty policy or contact Dorman customer support.
Support and Resources
For additional support, product information, or to find the correct application for your vehicle, please visit the official Dorman website:
You can also explore Dorman's brand store on Amazon for a wide range of automotive solutions:
Official Product Videos
Why Choose Dorman's Exhaust Manifolds?
This video from Dorman Products explains the critical role of exhaust manifolds, the challenges they face due to extreme heat, and how Dorman's comprehensive line of manifolds, including CARB compliant options, provides reliable and durable solutions for various vehicles. It highlights the manufacturing to OE specifications and the inclusion of necessary hardware for simplified installation.
Make Dorman your exhaust manifold repair solution
This video from Dorman Products showcases their commitment to providing complete exhaust solutions. It emphasizes the rigorous engineering behind their replacement manifolds, including both conventional and CARB compliant integrated converters, and the use of upgraded components like ceramic-coated manifolds and stainless steel hardware to ensure durability and ease of repair.
