879150054 Thermostat for MerCruiser Cummins 2.0L | JLM Marine

Thermostat for MerCruiser Cummins 2.0L – 879150054

This high-quality aftermarket thermostat is engineered to fit MerCruiser and Cummins marine 2.0L inline 4-cylinder diesel engines, covering both stern drive and inboard configurations. Designed for models ranging from 115HP to 170HP, this thermostat ensures reliable temperature regulation across a wide range of VM, CMD, and QSD engine series.

Direct replacement for OEM part number 879150054, this thermostat fits heat exchanger systems on Mercury MerCruiser diesel applications. It maintains optimal engine operating temperature to protect against overheating and ensure consistent performance on the water.

• Fits MerCruiser 2.0L diesel engines (115HP–170HP) with heat exchanger cooling
• Direct OEM-spec replacement for Mercury part 879150054
• Compatible with VM, CMD, and QSD inline 4-cylinder diesel models

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below.

Technical Specifications

Package Contents

• 1 × Thermostat (OEM Part 879150054)

Installation Guide

1. Allow the engine to cool completely before starting any work. Ensure the vessel is secured and the battery is disconnected.
2. Locate the thermostat housing on the heat exchanger assembly of your 2.0L diesel engine. Reference your service manual for exact placement.
3. Drain coolant from the system by opening the drain plug; have a clean container ready to catch the fluid.
4. Remove the bolts or clamps securing the thermostat housing cover using the appropriate socket or wrench.
5. Carefully lift off the housing cover and remove the old thermostat. Note the orientation of the thermostat before removal.
6. Clean the mating surfaces on both the housing and cover to remove old gasket material and debris. Inspect for cracks or damage.
7. Install the new thermostat in the same orientation as the old one, ensuring the spring mechanism faces the correct direction (typically toward the engine block).
8. Apply a thin, even coat of gasket sealant if required by your engine's service manual, or install a new gasket if provided.
9. Reattach the thermostat housing cover and torque the bolts to manufacturer specifications in a crisscross pattern.
10. Refill the cooling system with the manufacturer-recommended coolant mixture, ensuring proper fluid level.
11. Bleed air from the cooling system per your engine's service procedure to prevent air pockets.
12. Reconnect the battery, start the engine, and monitor coolant temperature and check for leaks around the thermostat housing.

Troubleshooting & FAQ

Q: How do I confirm this thermostat fits my MerCruiser diesel engine?
A: Cross-reference your engine's serial number with the compatibility table above. Verify that your engine model, horsepower rating, and serial range match one of the listed configurations. You can also compare the part number 879150054 with your original thermostat.

Q: What are the signs that my thermostat needs replacement?
A: Common symptoms include engine overheating, fluctuating temperature gauge readings, poor cabin heater performance, or coolant leaks around the thermostat housing. If your engine runs too hot or too cold, the thermostat may be stuck closed or open.

Q: How often should I replace the thermostat on my 2.0L diesel engine?
A: Thermostats should be inspected during regular cooling system maintenance (typically every 2–3 years or per manufacturer intervals). Replace immediately if you notice overheating, temperature irregularities, or visible damage during inspection.

Q: Can I install this thermostat myself, or do I need a professional?
A: If you have mechanical experience and the proper tools, installation is straightforward following the steps outlined above. However, professional installation is recommended to ensure proper coolant system bleeding, torque specifications, and leak-free operation.

Q: Is this an OEM part or an aftermarket replacement?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.