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Thread: Auto trans solenoids stuck; how to unstick?

  1. #1
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    Auto trans solenoids stuck; how to unstick?

    My friend and I fixed my DeLorean's automatic transmission's "transmission fluid leaking into the final drive" problem -- it seems the orange RTV used on the tube that carries ATF to the torque converter was falling apart, which was causing the failure. We resealed it and it's good to go. We also replaced the C2 and B1 packs (whichever two are relatively easy to reach with no special tools), although they looked to be in quite good shape with no significant wear. There were a few burn marks on the top ring, but everything else looked fine.

    Took it for a test drive, but I only have first -- it doesn't shift at all. The diagnostic plug showed that they should have been triggered (both pins were ground). Pulled the solenoids and hooked the up to a 12v battery, and they still don't move. You can feel them try to shift slightly, but they don't actually open.

    Best guess is that for the week or so that we had the trans open, they rusted a little. Which seems odd, but whatever's going on, they're not moving. We filled them with brake clean and then WD 40, tapping them lightly with a hammer while also tapping the wire to the battery to try to jar them free. A couple of times we felt a strong click as the solenoid opened, but that's it.

    Anyone know how to get these unstuck? Is there some trick? Do the balls slide or rotate? I'm guessing slide; if so, is it possible to push to break them free without damaging them?

    Thanks!

    -- Joe

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    There was a case a while back where silicone got stuck in a solenoid. It was a big blob and was easy to remove once the solenoid was taken out. My guess for you is there is silicone that got INSIDE your solenoid valve preventing the innards from moving properly. I do not know of any way to disassemble them. If you can't get it to work you probably have to replace them. Verify the shift computer is actually powering the solenoids. Build a light box. It plugs into the diagnostic plug and the lights light up when the shift computer commands a shift. You can do this on a bench with a drill, a battery and a light box and a bunch of jumpers. The logic table is G:04:01. Also inspect the wiring harness for heat damage. If the wires get close to the exhaust pipes they get burnt.
    David Teitelbaum

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    I agree that it would be odd for the solenoids to seize up like that...
    Just in case- Those 2 brass terminals connect to the 2 solenoids and are grounded by the GC for 1st. The GC feeds the other side of the coils 12V all of the time.
    Did you pull the trans fuse to see if it went into 3rd?

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    I used a PowerProbe to test the diagnostic port pins that go to the solenoids (ie: the pins used for the test light). In first, both pins are grounded as expected.

    I did not try pulling the transmission fuse; didn’t think of that. I'll try that tomorrow. I understand why that would work; I'm annoyed I didn't think of it myself.

    I did, however, hook up a multimeter to test the resistance. I get 25 Ohm on one solenoid and 26.4 on the other, so the coil appears to be intact. Also, it seems REALLY unlikely that both solenoids failed at exactly the same time.

    I found this 51 second video you YouTube that shows a test of a DeLorean solenoid valve: https://www.youtube.com/watch?v=Ov4acHXbCCI . If I understand the operation correctly, there is a surprisingly strong spring that pushes a shaft into the ball into the end of the valve, blocking the flow, and this is the default (unenergized) position. When energized, the solenoid pulls the shaft back and the ball can spin freely, and hydraulic pressure pushes fluid past the ball and into the valve body. I only just realized this, so my earlier testing may have been of limited value, although I would have expected the ball to roll way when the solenoid was energized -- it seemed to just stay put and not move, and fluid placed on the end didn't drain through it. We've also tried spraying them with brake cleaner, then WD-40, then letting them sit in a bath of Free All in case they were stuck, but so far, nothing.

    IMG_3119.jpg

    I notice the solenoids are out of stock on the DeLorean site, although DeLoreanGo has them for $265, so if all else fails I guess I can do that. Odd that DeLoreanGo has them but DeLorean.com doesn't.

    I'm going to see what happens tomorrow with the transmission fuse in and out. Maybe something about testing on the car is different than testing on the bench. I don't know.

    Thanks!

    -- Joe

  5. #5
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    Joe,
    That's an interesting video. It seems to show the valves are open to flow with the solenoid not energized, and shutting off flow with the solenoid energized.

    https://www.youtube.com/watch?v=Ov4acHXbCCI

    Ron

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    Huh; I was so focused on the operation that I didn’t notice that the ball only spun freely when not energized. Since I can’t spin the ball by hand when not energized, perhaps they are seized after all. Still, both of them, at the same time? It’s very strange.

    I’ll be at the garage where my car is in about two hours and can do the fuse test then.

    — Joe

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    After a night of soaking, the solenoid balls now move pretty easily by hand. When hooked up to the governor and powered in drive, they can no longer be turned — exactly as expected. When I pull fuse 13, the balls spin freely again.

    So it looks like they were seized. I have no idea why a week on the bench would do that, but it seems to work now.

    We have to re-seal the dipstick tube, put the pan back on and replace a leaking O-ring behind the driver’s output shaft (fun) but we expect to do a test drive in a a few hours. I mean, one way or another we have to — our bay time ends at noon.

    BTW, if anyone needs short-term bay space in the RI area, Gearhead is great for that — $20/hour for a full bay with a lift and tools, and $50/week to store your car if you need to come back to finish it another day. Much easier than pulling a transmission in your driveway.

    Thanks!

    — Joe

  8. #8
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    Update from a test drive:
    - Still only have first gear.
    - Removing fuse 13 gives me only third gear (or at least it’s not first gear).

    I’ll see if I can find further information on testing the governor, since I’m out of ideas.

    — Joe

  9. #9
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    So it appears that when we put the transmission together we forgot an adaptor that goes from the governor to a helical gear inside the transmission. Which I read as the transmission thinking that we’re just sitting there revving the engine and not actually moving. We’re on the way home know to figure out where it is in my basement (where we resealed it) and then coming back tomorrow to reinstall it. <sigh>

    — Joe

  10. #10
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    That makes sense. The shift computer thinks the car is not moving so it never commands an upshift. Get that piece in and it should work. We know the trans is working somewhat because you have 1st and 3rd.
    David Teitelbaum

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