Renault Megane 3 RS – issues after clutch, flywheel, and slave cylinder line replacement

a suggestion.
With the engine off, pump the clutch peddle half a dozen times and hold or wedge the clutch peddle down for around 10 minutes or longer if possible, then release the peddle.

 

Assuming new DM flywheel + clutch etc installation is correct (?), the likely cause of your problem is air remaining in hydraulic circuit

I used the syringe method when replacing my clutch line, and found it the best way to remove ALL air

Might be worthwhile giving it a try

 

If you're confident there is no air in the hydraulic circuit maybe consider either the master or slave cylinder being the problem?
Difficult to change the slave so maybe it's worth looking at the master cylinder??

 

From ChatGPT

Your symptoms point to a likely clutch engagement or hydraulic system issue, possibly compounded by gear synchronizer wear in the transmission. Here's a breakdown of what your observations suggest:

Likely Causes
1. Incomplete Clutch Disengagement
If the clutch isn’t fully disengaging when the pedal is pressed, it can make shifting into gear difficult — especially:

• 1st gear when stationary
  
  
• Grinds when going into 2nd or 3rd fast
  

You mentioned:

"Releasing and pressing the clutch again lets it go in fine"
This is a classic sign of incomplete disengagement.

Even though the pedal feels firm and consistent, the clutch may still not be disengaging fully due to:

• Slight air in the hydraulic line
  
  
• A weak master cylinder (even if there’s no leak)
  
  
• A sticky or dragging clutch disc, possibly due to:
  
  • Warped disc
    
    
  • Faulty pressure plate
    
    
  • Input shaft binding
    

2. Hydraulic System Marginal Performance
You said there are no leaks, and components are dry, which is good. But:

• A lazy clutch master or slave cylinder can still fail to deliver full movement
  
  
• Air in the system can cause soft or incomplete actuation, even with a firm-feeling pedal
  

➡️ A good bleed of the clutch system is inexpensive and worthwhile as a first diagnostic step.

3. Transmission Synchronizer Wear
The symptoms in 2nd and 3rd — grinding or graunching when shifting quickly — are typical of:

• Worn or slow synchronizers, especially if the clutch is okay
  
  
• This is more common in higher-mileage or aggressively-driven cars
  

4. Transmission Mounts or Linkage
Less likely, but worth checking:

• Worn transmission or engine mounts can slightly misalign linkage or cause torque movement that affects smooth engagement
  
  
• Shifter cable/linkage wear or misalignment can cause inconsistent gear feel
  

Suggested Tests / Checks

1. Clutch Drag Test (Simple DIY):
   
   • Engine off: Start in 1st gear, clutch pedal pressed.
     
     
   • Start engine with foot still on clutch:
     
     • If the car lurches forward, the clutch is dragging.
       
   • Or: try to shift into reverse (no synchro) while stationary — if it grinds, clutch isn’t fully disengaging.
     
2. Clutch Fluid Bleed:
   
   • Even a small air bubble can cause symptoms like yours.
     
     
   • Flush and bleed the system to eliminate this as a variable.
     
3. Check Clutch Fork / Slave Travel:
   
   • Have someone press the clutch while you observe slave cylinder travel.
     
     
   • Compare to spec or online videos for your car — short travel = incomplete disengagement.
     
4. Transmission Oil Check:
   
   • Old or wrong-weight oil can affect synchros.
     
     
   • Check level and condition; consider replacing with a high-quality GL-4 gear oil (if applicable).
     

⚠️ Summary Diagnosis
Symptom Likely Cause
Smooth shifting with engine off Clutch disengagement issue
Notchy or resistant with engine on Clutch or synchro issue
1st gear hard to engage at stop Clutch dragging
2nd/3rd grinding slightly Synchro wear or clutch dragging
Firm clutch pedal Hydraulics may still be weak/airlocked
✅ What To Do First

1. Bleed the clutch hydraulic system thoroughly
   
   
2. Inspect slave cylinder travel
   
   
3. Check transmission fluid
   
   
4. Test for clutch drag
   

If it persists after bleeding and confirming full clutch disengagement, it's time to consider:

• Clutch installation check/redo (disc, pressure plate, maybe flywheel resurface)
  

 

hello brother,did you solve your problem ?Because i have some similar symptoms like yours