Advice needed. 1965 401 engine noise?

Discussion in ''Da Nailhead' started by Terry R, Dec 19, 2018.

  1. Terry R

    Terry R GS Stage1 Ragtop 1972

    This is a rebuilt 401 with a matching rebuilt SP300 tranny. With the handbrake on and standing on the brakes,
    there is a loud noise when I torque it up to about 1,000 rpms in drive. The noise is a loud metal to metal rotating sound. It does not make the noise in reverse. When driving, it will make the noise only when I get on it. It is not a muffled noise like you hear in a torque convertor or transmission which are full of oil. It seems to be coming from the back end of the engine and sounds internal. I have eliminated the following: Flex plate, starter, and anything up under the tranny dust cover. With the car on a lift and using a stethoscope, it is loudest toward the back end of the engine. I know sounds can travel but it doesn't sound like the tranny or the torque convertor.
    Any suggestions on how I should proceed from here? This is driving me nuts.
  2. gsgtx

    gsgtx Silver Level contributor

    when in drive you are putting tq on the drivers side motor mount lifting the engine up on that side. can't be, but sounds like fan hitting, or torque convertor bolts hitting ? just guessing things. hang on the guys here will come up with something.
  3. Brad Conley

    Brad Conley Super Moderator Staff Member

    Check for rub marks on the underside of the hood from the power steering pump pulley. Had that happen on my '64 Electra as a youth from a broken motor mount.
  4. Terry R

    Terry R GS Stage1 Ragtop 1972

    Thanks Guys,
    The fan is clear and the torque converter bolts are clear. I don't have power steering. I had a guy tell me to try putting washers between the transmission and block bolts and see if it still made the grinding noise. Haven't tried that yet.
    Any further input is greatly appreciated.
  5. Wildcat GS

    Wildcat GS Wildcat GS

    I would have bet on a bad motor mount and the fan/shroud but the fact you are sure the sound is originating at the rear of the motor contradicts that. Maybe check the crank for end play for a start? Isnt there an issue with the crank hitting the oil pump when one of the fasteners/components becomes loose? Good luck,
  6. wkillgs

    wkillgs Gold Level Contributor

    My first thought was cracked flex plate or loose bolts. If one of the crank bolts is too long it can hit the block. Was the converter fully seated in the trans?
    And Tom T did once mention rod bolt nut to oil pump clearance, especially with replacement rod bolts.
    Last edited: Dec 20, 2018
  7. Terry R

    Terry R GS Stage1 Ragtop 1972

    Great suggestions Guys,
    I'll start with the crank end play - easy to check. Then pull the oil pan and check clearances: ie crank bolts, oil pump, etc. Will also check oil pan for metal shavings. It will be after the holidays before I can get back on it.
    Thanks much and Happy Holidays,
  8. gsgtx

    gsgtx Silver Level contributor

    it does not do it in reverse, so what changes in reverse that would stop the noise ? tranny related ?
  9. Mark Demko

    Mark Demko Well-Known Member

    The engine roll's or torques down on the left (drivers side) instead of up when in drive.
  10. Mark Demko

    Mark Demko Well-Known Member

    1000 rpm in drive.
    What does it do at 1000 rpm out of gear?
  11. Steven A

    Steven A Active Member

    I would check driveshaft. U joints, center support bearing if you car has 1.
  12. Dadrider

    Dadrider Silver Level contributor

    Do you have a converter cover on the bottom of your tranny? Had a 73 4V 350 that started doing that out of nowhere. Put it on a chassis dyno after a month of searching. The converter cover was bent in one spot by the flexplate and would grind at certain times.....

    Just a thought.

    Good luck with it.

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