Overdrive Problem; Won't Engage

[shorn]

So here I am up in Vancouver, BC for a long weekend in the Healey and without my service manual (Don't know how I left home without it, I almost never do); and the overdrive won't engage. First time I have had this problem. Actually it worked part of the way up here. Stopped for lunch. Got back on I-5 and it would not engage in either 3rd or 4th. I do, however, hear the lockout switch "click" with the ignition key "on" and the overdrive switch in "OD", shifting from 1st to 3rd or 4th.. Redline MT90 in the tranny and reads full.
While I don't have my full compliment of tools and may not be able to check it out, I probably can pull the tunnel. Without my manual, can somebody clue me for the first couple of things to look for?

 

[bighly]

With the tunnel off. Check if it will engage by manually pulling the lever. If so the problem is probably that you need to adjust the lever slightly so it engages.

BE VERY CARFEFUL WHEN DRIVING WITH THE TUNNEL OFF !!!

There is a spinning yolk next to your right hand. Be sure not to get seatbelts clothes etc tangled in this spinning danger zone.

If it does engage by hand your electronics are probably ok.

Let us know how this test goes.

 

[shorn]

Since I am not at home, it took me awhile to get the tunnel off. Just did. So far the toggle switch is working. The overdrive relay can be heard clicking in and out. The trottle switch will click off with the OD switch in the off position and the accel pedal pushed down as designed. And the gear switch clicks on and off as the gear shift is moved from right to left and back. However, I do not hear the OD solenoid activate at any time. I assume with the tunnel off, it should be heard. I have not tried activate the the OD manually with the lever as yet. I am in a garage with the top down and its raining so I may wait for further testing tomorrow.

 

[shorn]

Forget what I said about the solenoid. It is working. It is fairly loud here. I heard the relay and gear cut out switch but not the solenoid. Now I do. I use to produce rock concerts and don't hear all that well. Anyway, I put my hand on the solenoid and can feel it engage. Took a quick drive around but the OD will not kick in. I suppose the next step is to see if dirt or something has clogged up the op valve or if adjustment is correct.

 

[Dave Russell]

Hi Skip,
As Tracy said, while you are driving, transmission cover off, when you switch into OD, try pushing the lever on the RH side forward more fully into the engaged position.

There is some slack in the lever/solenoid travel which may make the travel marginal. If this works, the lever/valve needs adjusting for more travel, likely only a tiny amount of additional travel. There is a more precise method of setting the lever but this might get you by for now.

Put a piece of cardboard over the transmission rear & U joint to keep it from throwing grease all over & to keep your shirt tail out of the moving parts.
D

 

[shorn]

Thanks Dave and Tracy,
I will try the lever first thing tomorrow, which hopefully will just require an adjustment. Still raining here tonight, so said to heck with the Heaely & we went out to dinner. It would be much easier if problems would develop a little closer to home. A big thanks goes to our hotelier who has allowed me to work on the Healey in their garage and to use the PC to access the BCF.

 

[Healey 100]

For what it's worth, I have had the same symptom many times with my Healey and seen it on others: I believe it is usually caused by those tiny little contacts in the solenoid that select the "pull-in" windings on the solenoid. When the contact resisistance on these is more than a mere ohm or so, the pull-in current is way too low and the solenoid just cannot generate the force needed to lift that little ball in the hydraulic system and engage the OD. Testing the solenoid statically in the car and seeing that it moves the lever does not prove that it works: the force needed to move that lever is much higher when the car is underway and there is pressure in the OD hydraulic system. If you want to test it in your shop, jack up the rear wheels, put the car in high and bring the car up to speed to see if the solenoid can move the lever and engage the solenoid. You will know you probably have this problem if the OD will engage if you manually move the lever, but won't do the same with the solenoid.

I doubt if adjusting the linkage will make much difference in your car -- it worked before and there is little reason for those adjustments to have changed. I would sure check it out, but would not expect the problem to be there.

This electrical contact problem is difficult to diagnose, and if you work the solenoid by hand, it can change the resistance of those contacts, making your overdrive work or not work intermittantly. I have had this problem on the road and it can go away as quickly as it started, and the OD starts working again, sometimes for days at a time. This may happen to you!

If you have this problem, the only sure cure is a new solenoid (these are costly). I have filed the contacts and had limited success with that, but you never know if that will last.

Also make sure the ground connection on the solenoid is good, all that current needs too pass through the ground and the bottom of that solenoid is usually oily and greasy -- this is a Healey after all....

Good Luck

Bill S

 

[Dave Russell]

Hi Skip,
It's not too hard to diagnose the cutoff contact problem. The solenoid has a high current, about 10-12 amps, pull in coil & a low current, about one amp, hold in coil. When the solenoid is first energized, both coils should operate the solenoid & very momentarily draw around 12 amps. Almost instantaneously, the top contact, under the rubber boot, opens deenergizes the pull in coil, & drops the current level to the hold in coils one amp.

Connecting an ohmeter to the solenoid lead & ground should show about one ohm with the solenoid plunger down & about 12 ohms with the plunger fully up - when the contact opens.

If you remove the top rubber boot on the solenoid you can possibly clean/adjust the contact. As Bill says, it may get you by long enough to finish your trip. I cleaned one four years ago & it's still working.
Best of luck to you,
Dave

 

[Keoke]

Wow! you mean that 12 Volts across 1 Ohm which is 12 amps will not pull the solenoid in?? I have measured the pullin current on these solenoids and it runs close to 19 Amps.---Keoke- /bcforum/images/%%GRAEMLIN_URL%%/frown.gif

Skip, Maybe that MT90 oil be a bit too thin and some good 30/40 weight Valvolene VR1 oil may perk it up.

 

[shorn]

I got the Healey on the road this morning. When the OD solenoid is engaged by switching on the OD, the lever on the right side of the OD unit is pushed fully forward, but the OD does not engage. I tried pushing the lever farther forward, but there is no more play. A 3/16 drill bit fits in the holes when engaged. I guess my next effort should be to see if the operating valve is plugged up or the spring is broken. Wish I had my manual, but I think you can get the spring, ball and valve out with a magnet and a paper clip. Any other thoughts?

 

[Dave Russell]

Skip,
Attached is a drawing of the valve parts. The ball can be removed with a magnet or a bit of sticky grease on the end of a pencil. The long spindle valve (J) can be removed with a bit of stiff wire inserted into it's center.

The ball has a lower seat (F) on the aluminum housing. It ALSO has an upper seat (G) against the top of the spindle valve. Make sure that BOTH seats are clean & that the balls surface is not marred There is a tiny bleed hole (H) low on the side of the spindle valve. Make sure that this tiny hole & the valves center drilled passage are open.

Control valve adjustment:
The control valve located under a brass cap near the front RH side of the OD must be correctly adjusted. Under the brass cap is a spring, a spring follower, a control ball, & a long spindle valve. The ball should be 5/16 diameter. The ball lift is what controls shifting. The book method of putting a pin through the RH arm & adjusting the LH operating arm is not a very reliable method of setting the ball lift. Wear in any of the parts will change the required setting from the original pinned arm method.

The most accurate & reliable method of setting the valve lift is:
a- Set control valve ball lift to .030" to .040". Measure with dial indicator. Cap, spring, & spring follower removed. Adjust clamped operating arm. Verify lift by hand movement of the solenoid plunger, not the arm.

Since you don't have the dial indicator, visually estimate this travel at a little over 1/32". Too little lift & the OD will not operate. Too much lift could prevent the ball from seating on it's lower seat.
D

 

[shorn]

With no dial indicator here, I sort of decided to just wait until I got home on Sunday. It's only a couple of hours away, so no big deal without the OD. That decided, we jumped in the car to get a Starbucks and guess what. Yep, the OD worked. Jumped on a highway and it engaged when switched on and diengaged when switched off and accelerator depressed about a dozen times in a row. Why??? I haven't the faintest. Perhaps just playing around with it readjusted the lever enough to work properly or a piece of dirt dislodged in the op valve. But it works.
I might just leave the tranny tunnel a little loose though without the center counsel reinstalled. Wouldn't be surprised if this issue pops up again. Thanks for all your help. Another example of the benefits of the BCF and its members.

 

[Keoke]

Well I don't think the spring is broken but the OP Valve could be plugged up. Yes you can remove it using the method you defined. In the back of my mind I am wondering if the pump may not have failed. You can check and see if fluid is flowing when you remove the OP Valve plug.--Keoke


P.S. That last decision of yours is the best one today wait until you get it home .Don't need it to get home anyway.---Keoke-- /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif

P.S. Fist test at home should be a pressure test. The pressure should be at least 450 PSI and preferably at 490.

 

[Andy65]

Check the oil level in the transmission. If it is too high or too low, the overdrive won't engage. Yeah, I know you checked it before you left - so did I, but I lost nearly 3 qts despite having put a new gasket and teflon tape on the drain and tightening it well. Overdrive quit early probably when down a qt. Then, scared, I overfilled it and overdrive stopped again. Another thing, clean the contacts on the OD switch on the dash. They get oxidized and don't conduct current well.

If you can drive the car to the right mechanic, they can connect a pressure gauge while it is in the car. If it is not developing enough pressure it could be the pistons or the OD oil pump. My OD quit one time because the wheel of the OD oil pump that rides on the cam wore in half. Cam shot too. That was caused by improper assembly some time in the past which is easy to do when mating the OD to the gearbox.

 

[shorn]

OD is filled to a whisker above the full mark. It also did not function on the trip home from Vancouver. Surprise, surprise. Tomorrow, I will check the contacts in the solenoid. Might even just replace the solenoid anyway. Either way I will also check the lever adjustment. Then on to the operating valve to see if it is dirty. If all that fails, a run to my mechanic for a pressure test.

 

[shorn]

Back in Seattle today and thought I'de pull the tranny tunnel to get started on the OD. Better give the car a run first, at least to the Starbucks down the road. Well, well, the OD works today. Better jump on the freeway and check it out before pulling the tunnel off. Yep, OD engaged, works fine; disengaged, yep, still working. Let's try it 8 or 10 times. Yep, still works.
I know it is just waiting until I get the counsel back on before it quits again.
The lever seems to be adjusted ok. The local Moss distributer has a new solenoid in stock, so I just may change it to be on the safe side. Perhaps the contacts are dirty or it is just starting to fail intermittently.

 

[tahoe healey]

A while ago, I had a simular problem. It turned out to be a SMALL metal metal flake I found when I removed the cap, sitting on the top of the ball (D in above diagram). Don't want to think where the metal flake came from cause everything is just fine now. If it workes don't fix it (unless you are the government).

 

[shorn]

Today I picked up the new OD solenoid and removed the old (original Lucas) one. Very interesting--the plunger is somewhat corroded,so I can see why it might not always be working or fully engaging. But more importantly, I suppose, there is NO Rubber Boot on the plunger. Now mind you, this OD has worked for the last 4 years that I have owned the car until now, apparently w/o the boot. I can only guess how long it has been missing. For that matter I am not real sure what the purpose of the boot is other than the plunger rests on it when not engaged. In any event the new solenoid has been installed and the OD seems to be working.

 

[Dave Russell]

Obviously the boot on the top is important to protect the cut off contact.

I think you mean the lower boot between plunger & solenoid body? If so, I've never seen a solenoid that actually had this boot. Only pictures. It may have been useful on some of the earlier models that did not have the plunger & lever enclosed in a housing. Even on these models, I can imagine that a deteriorated boot could interfere with solenoid operation & cause more problems than it solves.
D

 

[shorn]

yes, Dave, I mean the lower one. The replacement solenoid had one. While it is harder to install to get the boot in place, I see no reason why it would be necessary. As you point out, I think it can cause more problems than it would solve should it tear or just age. In any event the new solenoid solved my problem and it seems to work with or w/o the lower boot.
Overall the original Lucas solenoid lasted 43 years. I'll bet the replacement made in wherever?? won't last that long.