FRAMING JOHN DELOREAN - ON VOD www.framingjohndeloreanfilm.com
Page 1 of 5 1 2 3 ... LastLast
Results 1 to 10 of 44

Thread: Clutch not working when hot

  1. #1
    Senior Member
    Join Date:  Dec 2018

    Posts:    980

    Clutch not working when hot

    Anybody have their clutch not work when hot? Today I drove the car for over an hour. Everything was fine. Parked the car in the full sun (for an hour) and it wouldn’t go in reverse. The clutch felt OK, but the gear shift would just grind. It went into first gear reluctantly. In the other forward gears I think it wasn’t working good, but it went better because I matched the rpms while shifting. I checked the fluid level and it’s full.

  2. #2
    Senior Member 82DMC12's Avatar
    Join Date:  May 2011

    Location:  Olathe, KS

    Posts:    1,128

    My VIN:    11596

    Been there done that. First make sure you've replaced the original plastic clutch line with a SS braided line. If you did that already and you don't see any leaks , flush and bleed the clutch. I have the DPI remote clutch bleeder which makes it so much easier. If you keep having to bleed it out , you probably have air getting in at either the master or slave cylinders. Check for fluid leaking into the foot well where the clutch master is bolted to the firewall.

    Sent from my Pixel 3a using Tapatalk
    Andy Lien

    VIN 11596 Jan 1982 build - owned since Nov. 2000!

    Photography and Backpacking is life.

    Was Fargo, ND
    Now Olathe, KS

  3. #3
    Administrator Ron's Avatar
    Join Date:  Jun 2011

    Location:  North GA

    Posts:    5,979

    Club(s):   (SEDOC) (DCUK)

    +1

    And if you can find no leaks, suspect a seal bypassing internally...

  4. #4
    Senior Member
    Join Date:  Dec 2018

    Posts:    980

    Quote Originally Posted by 82DMC12 View Post
    Been there done that. First make sure you've replaced the original plastic clutch line with a SS braided line. If you did that already and you don't see any leaks , flush and bleed the clutch. I have the DPI remote clutch bleeder which makes it so much easier. If you keep having to bleed it out , you probably have air getting in at either the master or slave cylinders. Check for fluid leaking into the foot well where the clutch master is bolted to the firewall.

    Sent from my Pixel 3a using Tapatalk
    Mine has the SS lines. Iíll check for leaks. Wouldnít the fluid go down?

  5. #5
    Senior Member 82DMC12's Avatar
    Join Date:  May 2011

    Location:  Olathe, KS

    Posts:    1,128

    My VIN:    11596

    Quote Originally Posted by Helirich View Post
    Mine has the SS lines. Iíll check for leaks. Wouldnít the fluid go down?
    Doesn't take much of a leak at all to draw air into the line. The piston barely moves anyway, and air compresses; fluid does not.

    Sent from my Pixel 3a using Tapatalk
    Andy Lien

    VIN 11596 Jan 1982 build - owned since Nov. 2000!

    Photography and Backpacking is life.

    Was Fargo, ND
    Now Olathe, KS

  6. #6
    Senior Member
    Join Date:  Dec 2018

    Posts:    980

    So I checked for leaks in the floor. Itís all dry there. I noticed that the pedal will go down an inch before it actually does anything. Seems like I brought this up before when it wasnít as bad. I think my master is about a year old. Maybe itís no good. I could extend the linkage to take up the play, but Iím wondering if that will just make the pedal bottom out sooner. Does the spring ever ware out in the master? Maybe poor machining catches the piston?

  7. #7
    Senior Member 82DMC12's Avatar
    Join Date:  May 2011

    Location:  Olathe, KS

    Posts:    1,128

    My VIN:    11596

    It's almost certainly air in the clutch line. The master is pushing in, the air is compressing, and once the air is compressed, the fluid finally moves and makes the slave work. That's why the pedal moves so far before the slave starts to work.

    Sent from my Pixel 3a using Tapatalk
    Andy Lien

    VIN 11596 Jan 1982 build - owned since Nov. 2000!

    Photography and Backpacking is life.

    Was Fargo, ND
    Now Olathe, KS

  8. #8
    Senior Member Rich's Avatar
    Join Date:  May 2011

    Location:  San Francisco Bay Area, Calif.

    Posts:    1,914

    My VIN:    0934

    Club(s):   (NCDMC) (DCUK)

    Does the problem disappear after the car cools down, as if the master and slave are both OK? Only happens when you hot-soak it, parked after a long drive on a hot day, especially at low speeds around town before parking?

    Then the clutch fluid is probably boiling inside the SS line back there above the drivetrain.

    1. Check the routing of the SS clutch line. Be sure none of it got coiled too close to the exhaust crossover pipe.

    2. Be sure there are still 2 complete heat shields bolted onto the crossover, Items 10-11 in this schematic.

    I assume you aren't running headers (no crossover in that case).
    March '81, 5-speed, black interior

  9. #9
    Senior Member
    Join Date:  Dec 2018

    Posts:    980

    Quote Originally Posted by 82DMC12 View Post
    It's almost certainly air in the clutch line. The master is pushing in, the air is compressing, and once the air is compressed, the fluid finally moves and makes the slave work. That's why the pedal moves so far before the slave starts to work.
    I believe the rod is not hitting anything during the inch of pedal travel. If it was air, I think it would have some resistance and than get harder when it moves fluid. I realize squeezing air is not much, but the piston and seal have to move. (Or should move) Iím thinking the piston/seal is stuck down a bit.

    Quote Originally Posted by Rich View Post
    Does the problem disappear after the car cools down, as if the master and slave are both OK? Only happens when you hot-soak it, parked after a long drive on a hot day, especially at low speeds around town before parking?

    Then the clutch fluid is probably boiling inside the SS line back there above the drivetrain.

    1. Check the routing of the SS clutch line. Be sure none of it got coiled too close to the exhaust crossover pipe.

    2. Be sure there are still 2 complete heat shields bolted onto the crossover, Items 10-11 in this schematic.

    I assume you aren't running headers (no crossover in that case).
    Iím not sure if it will disappear this time, but it has in the past. In the past, I needed to push every last bit to work the clutch. This time, I pulled the carpet clear and pushed till I got to the floor and still it would not disengage. I have headers. Not sure if the line can get hot on something else. Iíll look in to it.

  10. #10
    Senior Member
    Join Date:  Dec 2016

    Posts:    412

    Quote Originally Posted by 82DMC12 View Post
    It's almost certainly air in the clutch line. The master is pushing in, the air is compressing, and once the air is compressed, the fluid finally moves and makes the slave work. That's why the pedal moves so far before the slave starts to work.
    Agreed. Air in the clutch line would seem the most likely suspect. If the air is trapped where it gets heated, it expands in volume, pushing clutch(brake) fluid back to the reservoir. So, when it's hot, the area ratio of air to liquid increases. The result is more air compression and less actual slave piston movement with a given clutch peddle displacement.

    Ron

Page 1 of 5 1 2 3 ... LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •