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How to plug cooling tube drain

Discussion in 'Workshop Forum' started by carl, May 16, 2018.

  1. carl

    carl True Classic

    Location:
    Virginia
    For the first time ever, I used the little drain screws at the front of the boxed cooling pipes and of course found the drain screw port threads were shot and I can't get a drain screw to tighten up. I don't plan to use these drains anymore (I'll go back to using the radiator drain plug). Do I:

    1. fill the drain port with JB weld?
    2, slobber JB Weld on the screw and then shove it into the hole?
    3. Tap for a larger size bolt (which I really don't need to do since I'm not going to use this as a drain).
    4. Some other option.....keep it simple.
     
  2. lookforjoe

    lookforjoe True Classic

    Can you use a thread chaser (similar to a tap) and revive the threads? Just shoving the screw in with anything isn't likely to be a permanent solution (in part due to lack of ability to thoroughly clean ports in-situ), and I don't think you want those leaking under pressure when the motor is running.
     
  3. carl

    carl True Classic

    Location:
    Virginia
    That's the first thing I did, they are just corroded away to the point they don't grab the threads on the screw or even a replacement screw. Oddly enough, the 1500 motor in this car must have come from a 79 as there are four globs of JB plugging the four air injection ports. Maybe this car is just meant to have 10 pounds of JB Weld.
     
  4. Dan Sarandrea (Phila)

    Dan Sarandrea (Phila) Waitin' On Parts...

    Location:
    Philadelphia, PA
    #1 and #2: Nope, we're better than that!

    #3: Very good option.

    #4: How about a couple of Time-Serts?
     
  5. beezee

    beezee True Classic

    How about smearing JB weld on the screw, insert it in the hole and tighten it the best you can, and then using a hose clamp around the pipe and over the head of the screw to keep it in place?
     
  6. ng_randolph

    ng_randolph Bjorn H

    Location:
    SF Bay area
    Perhaps, but see Dan Sarandrea's #1 and #2: above...
     
  7. carl

    carl True Classic

    Location:
    Virginia
    If I go with an over size bolt, #3, what size is next up that I can get locally, bolts that use a 13mm wrench are a tad large. Why do you guys make my life so difficult (answer: because I'm working on X1/9s instead of 124 spiders).
     
  8. Dan Sarandrea (Phila)

    Dan Sarandrea (Phila) Waitin' On Parts...

    Location:
    Philadelphia, PA
    IIRC, those small capscrews have 10mm heads but are 6mm x 1.xx (00 or 25, can't remember which).

    Just curious if you have enough meat on the drain hole bungs to drill the existing holes with a 17/64 drill and then tap for 8mm x 1.25. With those drain holes, the copper crush washer under the capscrew head does the sealing, the threads do not, but if you consume too much of the bung's shoulder by drilling to a larger metric size, you might not have enough sealing surface left. In that case, I'd look to see if there were a common SAE size that fell in the middle between the 6mm and the 8mm size.
     
  9. carl

    carl True Classic

    Location:
    Virginia
    There is plenty of meat on that bung to go to from M6 to M8. The JB option was mentioned as I never planned to use that bung as a drain.
     
  10. lookforjoe

    lookforjoe True Classic

    Why not just use 1/8 NPT plugs then? If the bolts were 8mm (?) should be able to tap for 1/8 NPT, no? Those would be easy to get in a variety of styles. Then use pipe dope or teflon tape.
     
  11. carl

    carl True Classic

    Location:
    Virginia
    IMG_0231[1].JPG

    OK, I tapped the hole for an M8 size bolt and found a copper washer to fit. Added some Teflon goop for the threads and I'm done, I hope. I noticed while down there that the front metal pipe appears welded to the pipe that goes through the box. Both sections are steel, and the curved front section seems original and undisturbed from when the car was built....how odd since I thought these were one piece pipes.
     
  12. lookforjoe

    lookforjoe True Classic

    That certainly does appear to be a weld joint. I guess it was cheaper to produce the shorter mandrel bend section & weld to a long straight than do it all as one? Never looked at mine to see if such a seam is present. No way that was done after the installation.
     

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