Hi everyone,
I'm planning to change the coolant on my 2017 Outlander V6 (nearly 9 years old now). I’ve looked for DIY videos on YouTube but can’t find anything specific to the 3.0L Gen 3.

A few questions for those who have done it:

1. Drain Amount: The manual says 9.3 quarts (8.8L). If I just use the radiator drain valve, how much actually comes out? Is it possible to get the full 10 quartz’s?
   
2. Bleeding: Is there a hidden bleeding valve on the 6B31 engine, or is it strictly 'burping' through the radiator cap?
   
3. Process: Is the standard 'run to temp with cap off, cool, and top up' method sufficient for this V6, or is it prone to airlocks?
   

Any tips on avoiding a mess or ensuring I don't leave 50% of the old fluid in the block would be appreciated!

Thanks,
Petar

 

outlander 2017 v6 mitsubishi engine coolant replacement procedure step by step from Co-Pilot AI
See my thinkingfNice project to tackle, that 3.0 V6 is a good engine to take care of.

Overview

You’re doing an engine coolant change on a 2017 Outlander 3.0L V6 (6B31). Below is a practical, step‑by‑step version based on the service manual procedure for the 3.0L and the updated coolant change bulletin for 2014–2017 Outlanders.

1. Prep and safety

• Cool engine: Let the engine cool completely—coolant can be under pressure and very hot.
  
• Raise front (optional but helpful): Use ramps or jack + stands if you need better access to the lower splash shield.
  
• Tools and supplies:
  • Pre‑mixed Mitsubishi‑approved coolant (or correct concentrate + distilled water)
    
  • Drain pan
    
  • Basic sockets/screwdrivers for under cover
    
  • Funnel
    
  • Rags and safety glasses
    

2. Remove the front under cover

• Remove engine room under cover front B (front splash shield) to access the radiator drain.
  
• It’s held by a mix of clips and bolts—drop only the front section you need.
  

3. Safely open the system

• Remove radiator cap carefully:
  • Place a rag over the cap.
    
  • Turn it slightly counter‑clockwise to bleed off any residual pressure.
    
  • Once pressure is gone, remove it fully.
    

4. Drain the old coolant

• Radiator drain plug:
  • Position your drain pan under the radiator drain (bottom of radiator).
    
  • Open the drain plug and let coolant flow out.
    
• Reservoir (condenser tank):
  • Remove and drain the coolant reservoir (overflow tank) as well.
    
• Let it drain until the flow slows to a drip.
  

(On this engine, the main drain is at the radiator; the bulletin corrects the procedure but still uses the radiator drain + reservoir for normal service.)

5. Optional quick flush

• Flush with clean water (simple version):
  • Close the radiator drain plug.
    
  • Fill the radiator with clean water.
    
  • Start the engine, heater on HOT, let it run until warm and the upper hose gets hot.
    
  • Shut off, let cool, then drain again from the radiator and reservoir.
    
• Repeat until what drains out looks reasonably clear.
  

The manual also describes flushing by injecting water from the radiator cap area to clean the coolant path.

6. Close everything up for refill

• Tighten radiator drain plug securely (snug, not gorilla‑tight).
  
• Reinstall the reservoir if you removed it.
  

7. Refill with new coolant

• Radiator:
  • Using a funnel, slowly fill the radiator with the correct coolant until it’s full at the neck.
    
• Reservoir:
  • Fill the reservoir to the “FULL” mark with the same coolant.
    

If you know whether you’re using premix or concentrate, we can sanity‑check the total volume, but follow the capacity in the manual/TSB for your exact engine.

8. Bleed air from the system

• Heater on HOT, fan low.
  
• Start the engine with the radiator cap off and let it idle.
  
• Watch the coolant level in the radiator neck:
  • As the thermostat opens, the level may drop—top it up as needed.
    
  • You’ll see bubbles escape; wait until they mostly stop.
    
• Gently rev to about 2,000 rpm a few times to help purge air.
  

When the level stabilizes and no more bubbles appear, top off to the neck and install the radiator cap.

9. Final checks

• Check reservoir level again and adjust to the FULL mark.
  
• Reinstall the under cover if you removed it.
  
• Take a short drive, let it fully cool, then:
  • Recheck reservoir level.
    
  • Inspect for leaks around the radiator drain, hoses, and reservoir.
    

If you tell me what coolant brand/type you bought, I can confirm if it matches what Mitsubishi calls for on that 2017 V6 and whether you should be using it straight or mixed.

is there a bleeder valve to open somewhereShort answer, : No — your 2017 Outlander 3.0 V6 (6B31) does not have a coolant bleeder valve.

Mitsubishi didn’t put a bleeder screw on the thermostat housing, radiator, or heater lines for this engine. That’s why every service manual and forum write‑up (including the one you have open) describes bleeding it through the radiator neck only, using heat‑cycle + topping off.

Here’s the clean way to think about it:

✅ Why there’s no bleeder valve

The 6B31 V6 uses:

• A high‑mounted radiator cap (highest point in the system)
  
• A self‑purging heater core
  
• A thermostat located low in the coolant path
  

Because of that design, Mitsubishi relies on:

• Filling at the radiator neck
  
• Running the engine with the cap off
  
• Letting the thermostat open
  
• Allowing air to escape naturally
  

No manual bleeder is needed.

🔧 How to bleed it correctly (since there’s no valve)

This is the method Mitsubishi specifies:

1. Fill radiator completely to the neck.
   
2. Fill reservoir to FULL.
   
3. Heater ON HOT.
   
4. Start engine with radiator cap off.
   
5. Let it idle until the upper radiator hose gets hot (thermostat opened).
   
6. Add coolant as the level drops.
   
7. Rev gently to ~2,000 rpm a few times to push out trapped air.
   
8. When no more bubbles appear, top off and install the cap.
   
9. After cooling, recheck reservoir level.
   

This is exactly how the 6B31 is designed to purge air.