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Overdrive stuck

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ClassicBritish

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So, I finally got our Austin Healey BJ7 out for the first time. I drove it to my office. On the drive over the fuel pump starting clicking. Quietly, then loudly. When I got to work....it ran out of 'go.' So I did a search on here and found the pump is probably sucking in air. Got the car in the air, and sure enough, one of the rubber hoses had a crack. So, I cut the damage bit off and put it back in place...problem solved.

Now I've given the forum a pat on the back for helping with that issue. Here is issue number two. On the drive over, I engaged overdrive (first time driving the car and first time using an overdrive). All seemed to be fine. Got into 4th and flipped the switch...and voila...it works. Came to a red light, turned off the overdrive and waited for the green light. Off we go, 1st to 2nd. 2nd to 3rd and halfway through 3rd gear it drops RPMs like the overdrive has kicked in (switch is still in 'normal' mode). Then shift to 4th and it's clearly in overdrive the entire time I'm in 4th. No amount of flipping switches, stopping the car and going again seems to stop it.

So current situation is the 1st and 2nd seem normal, then no matter where the switch is placed the overdrive seems to self activate part the way through 3rd and stay on going into 4th.

HELP!
 
First of all, DO NOT try to use reverse. it could really hurt the OD bad. My suggestion would be to get the rear end off the ground and then try to hand turn the rear wheels with the tranny in reverse. If you can't, then you know it is definitely stuck in OD. Next thing i would do, because i've done it before on Bruce Phillips suggestion, i hit the OD with a hammer where it joins the tranny. There is a steel ring there i think. That freed mine up and i was able to drive home from Vermont without fear of backing up.
A couple of good wracks should do it. Do this before letting the car down so you can again try to move the rear wheels with the car still in reverse.
My experience, others may have better/easier suggestions.
 
Bob McElwee said:
First of all, DO NOT try to use reverse. it could really hurt the OD bad. My suggestion would be to get the rear end off the ground and then try to hand turn the rear wheels with the tranny in reverse. If you can't, then you know it is definitely stuck in OD. Next thing i would do, because i've done it before on Bruce Phillips suggestion, i hit the OD with a hammer where it joins the tranny. There is a steel ring there i think. That freed mine up and i was able to drive home from Vermont without fear of backing up.
A couple of good wracks should do it. Do this before letting the car down so you can again try to move the rear wheels with the car still in reverse.
My experience, others may have better/easier suggestions.
Click to expand...

I'll give it a go.
 
If it was mechanically locked in OD, it would start out in OD in all froward gears (and, as ClassicBritish says, would ruin itself if you reversed). Since you describe it shifting into OD during your 3rd gear use, that says it is mechanically dropping out of OD when you stop. When you stop, hydraulic pressure quits so it would drop out of OD, and you usually need to be in 3rd to get enough hydraulic pressure to make it shift into OD. You indicate it shifts into OD without using the dash switch so somehow the solenoid is staying energized and my first guess would be the throttle switch is bad or adjusted wrong, should take about 1/4 throttle to cut juice to the solenoid. By all means, avoid using reverse until you are sure the switches are working properly.
 
red57 said:
If it was mechanically locked in OD, it would start out in OD in all froward gears (and, as ClassicBritish says, would ruin itself if you reversed). Since you describe it shifting into OD during your 3rd gear use, that says it is mechanically dropping out of OD when you stop. When you stop, hydraulic pressure quits so it would drop out of OD, and you usually need to be in 3rd to get enough hydraulic pressure to make it shift into OD. You indicate it shifts into OD without using the dash switch so somehow the solenoid is staying energized and my first guess would be the throttle switch is bad or adjusted wrong, should take about 1/4 throttle to cut juice to the solenoid. By all means, avoid using reverse until you are sure the switches are working properly.
Click to expand...

I agree. Mine had mechanically locked in OD at one time, and it would be in OD in 2nd. I rarely use 1st.
 
I believe you said that this was the first time using the OD at least in quite awhile and you said that after it engaged in 3rd gear it never came out again even when you stopped. On my BJ7 I eliminated the throttle switch and I engage the OD manually by using the dash switch to engergize the OD relay. I've been driving it that way for the better part of 20 years. I just make sure that I don't disingage it when decelerating. (always give it a blip of the throttle when fipping the switch off). Or use the clutch, this avoids a hard jolt to the driveline when coming out of OD. So there are many times when I come to a complete stop and forget that I am still in OD. Now remember that there is the little switch on the 3 and 4 shift pattern. If the shift lever is not on the 3-4 side of the shift pattern the OD can not engage. In my car I can heard the little switch clicking as I go from neutral to third. IF THIS LITTLE SWITCH IS WORKING AS IT SHOULD, THE OD CANNOT ENGAGE WHEN YOU PULL THE SHIFTER TOWARDS REVERSE. Albeit it is a good idea to not test the system that way. Having said all of this, I would check the wiring on the OD relay or checkout the internal circuit of the Relay to diagnosis this problem.
 
vette said:
I believe you said that this was the first time using the OD at least in quite awhile and you said that after it engaged in 3rd gear it never came out again even when you stopped. On my BJ7 I eliminated the throttle switch and I engage the OD manually by using the dash switch to engergize the OD relay. I've been driving it that way for the better part of 20 years. I just make sure that I don't disingage it when decelerating. (always give it a blip of the throttle when fipping the switch off). Or use the clutch, this avoids a hard jolt to the driveline when coming out of OD. So there are many times when I come to a complete stop and forget that I am still in OD. Now remember that there is the little switch on the 3 and 4 shift pattern. If the shift lever is not on the 3-4 side of the shift pattern the OD can not engage. In my car I can heard the little switch clicking as I go from neutral to third. IF THIS LITTLE SWITCH IS WORKING AS IT SHOULD, THE OD CANNOT ENGAGE WHEN YOU PULL THE SHIFTER TOWARDS REVERSE. Albeit it is a good idea to not test the system that way. Having said all of this, I would check the wiring on the OD relay or checkout the internal circuit of the Relay to diagnosis this problem.
Click to expand...

Thanks. I will take a hammer to the overdrive unit next time I mess with it and see if that frees it up. If it's not stuck then I will start pulling switches and relays to find the fault. I have a feeling that at the first time I turned the switch on that it worked, that most likely the OD is stuck and not a electrical issue.
 
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