Backfire during kickdown with OD

Jon B
Jon B Administrator
edited June 2013 in HUDSON
When I tromp it to the floor to downshift, sometimes it backfires. Never used to do this.

The overdrive is a "first generation" (or maybe second?), 1940, semi-electric. The operation might be different from the 1941 and newer OD's.

The solenoid breaks the ignition circuit during downshift. So I'm suspecting that something in the solenoid is hanging up and giving more of a delay than normal (thus allowing unburned gas to accumulate in the exhaust, before the spark is restored). If so, can these solenoids be easily repaired, or do I rummage around for the spare that I think I bought?

Ideas are gratefully appreciated!

Comments

  • RL Chilton
    RL Chilton Administrator, Member
    Jon-
    Your logic is sound. Sounds like the solenoid to me. I would give Dr. Doug a call and ask him, to be sure. If you do need a new solenoid (can't find the extra one), I know he has them.
  • PAULARGETYPE
    PAULARGETYPE Senior Contributor
    IF THAT IS A 40 OVERDRIVE IN YOUR 37 JON THAT IS A DIFFERENT SOLENOID IT FITS 40 ONLY IT IS NOT THE 41 TO 47 TYPE AND IS NOT THE 48 TO 54 TYPE NOT SO EASY ONE TO FIND
  • Jon B
    Jon B Administrator
    Thought I'd write a conclusion to this thread. Today I pulled the old solenoid and replaced it with a NOS one I had. (The old one was NOS 35 years ago, so I got my money's worth). The upshot was, that the car downshifts instantly and with no delay or backfire, so I can only conclude that the problem was in the solenoid itself.
  • RL Chilton
    RL Chilton Administrator, Member
    Glad you got it solved, Jon!
  • hudsonsplasher1
    hudsonsplasher1 Senior Contributor
    That's good Jon. I like it when people come back on with the solution.
  • DocHornet
    DocHornet Expert Adviser
    I've had similar problems with the B/W Overdrive unit on my Nash-Healey LeMans Coupe. In fact, I destroyed a near-new muffler with a backfire after the engine went dead on deceleration and then restarted. Nash-Healey gurus tell me it's almost certainly an issue with the solenoid. I removed mine, cleaned it up, including the contacts. So far, no further occurrence of the problem
  • Jon B
    Jon B Administrator
    I was afraid of destroying the muffler, because the whole exhaust system is only 29 years old, and I believe in getting my money's worth! (And, sadly, Jim Fortin is no longer with us, so I probably will never find another muffler that durable...)
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