I have a '64 BJ8.

I have a sporadic problem with my overdrive. At times it begins to jump into and out of overdrive unpredictably. This can be disconcerting when cruising at highway speeds.

I think that it happens primarily when the car gets really hot (long trips on hot days), but I can't swear to that correlation.

Any ideas on what's causing the problem and how to tackle it?

Subject: SOL Examination Paper 1: Lucas Overdrive Solenoids OK, guys'n gals, time to test your claim to be the genuine Scions of Lucas: Lucas overdrive operating solenoid - it's that bulge on the side of the overdrive unit that gets hotter and hotter and then tries to burst into flames if it can't achieve its goal of shifting the overdrive oil ball valve. 1) Is it normal behaviour for a solenoid to get too hot when it cannot pull its core completely into the coil winding? 2) Is it possible for it to draw so much current as to melt the supply wires before melting its own internal windings? 3) Is it possible that it has partially destroyed its own internal winding's insulation such that it shorts maybe 1/2 the winding and hence draws twice the current next time it's operated (I=V/R)? It still gives a hearty kick when energised but obviously not enough to operate the valve and stop it burning up. Anyone know what "R" should be on a healthy solenoid? 4) Shouldn't the fuse blow before igniting the whole car, not afterwards? (the wiring seems to be original and pretty heavy gauge). 5) How many 1000 turns of what gauge wire should I rewind the solenoid coil with? (new one is $150 from Moss :-( I checked the linkage to the valve and all appears to work smoothly so I don't know how it could have burnt out - maybe temporary mechanical obstruction of the exposed "overdrive calibration lever" on the far end of the OD camshaft? This is the later design of OD linkage which protects the solenoid mechanism but still leaves the exposed test lever on the opposite side which is very vulnerable to obstruction from the tranny cover for example (my tranny cover is a flimsy sort of moulded cardboard thing with not much solid in the way of floor panel remaining to screw it down to!). Andrew Smith Palo Alto, CA '60 Healey 3000 Mk.I (with Mk.II gearbox & overdrive units) From: HealeyDoc@aol.com Date: Fri, 8 Mar 1996 16:13:40 -0500 Subject: Re: overdrive problem The overdrive adjustment is set incorrectly. For more info on how to adjust the overdrive refer to Factory service manual page G4 section G6 or pages 53 - 55 In Normans tech book. ====================================================== British Car Specialist 2060 N. Wilson Way Stockton Ca 95205 209-948-8767 (fax# 948-1030) Healey Doc@aol.com Norman Nock - Tech. advisor, David Nock - Service Sheila Huggins - parts research Technical books by Norman Nock avalilable for the MG and Healey. From: Dave_Lapham-RMFV10Q@email.sps.mot.com Date: 8 Mar 96 09:05:53 -0600 To: PJBartels@aol.com Cc: healeys@autox.team.net Subject: RE>overdrive problem Reply to: RE>overdrive problem On: 3/7/96 PJBartels@aol.com wrote: > I have a sporadic problem with my overdrive. At times it > begins to jump into and out of overdrive unpredictably. > This can be disconcerting when cruising at highway speeds. > > I think that it happens primarily when the car gets really > hot (long trips on hot days), but I can't swear to that correlation. > > Any ideas on what's causing the problem and how to tackle it? While there are probably multiple possible causes, I just went through the same battle on my BN7. Here's what I did: Remove the seats and transmission tunnel. Check the travel on the solenoid and the 'calibration arm' on the other side of the overdrive ( use a 3/16" drill bit & line up the arm with the hole in the O/D body which is there for that purpose). Make sure the solenoid is actually pulling in. The manual has more details on doing this. Since your trouble is that the O/D is cutting out, you'll probably see and hear the solenoid pull in. Just make sure it's pulling in enough by using the above method. In my case, the problem was a bad solder joint on a bullet connector. Once I had determined that the solenoid pulled in and had enough travel, I started wiggling wires. Pretty soon the solenoid dropped out and I started checking with a test light until I found the problem. Good Luck. Dave Lapham Austin, TX Date: 09 Mar 96 20:36:35 EST From: Richard Schwartz <73641.3111@compuserve.com> Subject: RE> Overdrive Problem Regarding the overdrive that falls out when hot. I recently had a rebuilt trans and overdrive installed. The overdrive had the same problem. Check the solenoid operation and adjustment Try to manually activate the OD by moving the actuating lever on the right side (which is what the solenoid is really doing). This will tell you if the problem is solenoid related. If this doesn't do anything check the seat of the actuator piston. This is accessed via a cap on the top of the OD. Inside is a small spring, a small plunger, a ball and the valve. Remove the ball and the valve (with a pencil point or a magnet) and check the seat where the ball sits on the valve. The ball and seat must match PERFECTLY! If the lip of the seat looks even a little uneven oil is probably leaking past the ball when it thins out from heat and the OD is losing the hydraulic pressure needed to remain engaged. The recommended procedure for seating the ball and valve is to place the ball on the seat and then whack it with copper mallet. Make sure you place the valve on a piece of wood before you do so as not to damage the bottom end. Fortunately, I had a spare valve so I just dropped it in and the OD has been working since. One other thing, I read that the seals around the accumulator and inner pistons sometimes fail but a local expert told me this is very unusual. Good Luck, Rick 67 BJ8 From: Rmoment@aol.com Date: Sat, 1 Jul 1995 10:31:38 -0400 Subject: Re: SOL Examination Paper 1: ... The solenoid has a switch built in at the top of its internal bore. The resistance is low (about 3 ohms) when the plunger is down (un-energized). When the plunger is drawn up from energizing, it hits the switch at the top of the bore and increases the resistance (to tens of ohms or more -- I can't give you a value but it won't be infinite and will be noticeably higher than the low value), which also cuts down on the current. The reason for all this is that it takes more energy to get the plunger up into the full magnetic field, but little energy to hold it there. If the solenoid is overheating it is because the switch did not activate. How do you know your solenoid is operaing correctly? First, remove it from the overdrive by the two screws. Pull the case up and then remove the plunger by unhooking it from the operating lever forked end. Put the plunger into the case bore and measure the resistance between the wire and the case as you push the plunger up into the bore. At the very end you should see the effect of the internal switch operating. If you don't see a change you'll need to get a new solenoid (about $100 or so). If all is OK electrically, replace the plunger onto the operating lever and then the body onto the overdrive. Now you need to make the adjustment correct. The book tells about putting a 3/16" drill through the hole in the operating lever on the passenger side of the overdrive and lining it up with a similar hole in the case. THe lever will be moved about 1/4" over to line up. This sets the rod that pushes up on the ball valve so that this valve just opens. You can observe the action by removing the check valve cap and looking into the bore -- be sure not to lose the spring and plunger that fit under the cap screw!!! You should have first loosened the clamping bolt on the operating lever side that the solenoid works. With the 3/16" bit lining up the holes press the plunger up into the solenoid all the way. You can check with an ohm meter that the electrical switch is operating. Now tighten the lever arm clamping bolt. Remove the 3/16" drill. Go back over to the solenoid and push the plunger (not the actuating arm!!) up all the way. You should find that the actuating arm has a slight bit of free room to move up even further than the plunger pulls it, indicating that it is not restricting the plunger from its full stroke (and thus operatiing the internal switch). NOW you can reconnect the solenoid wire. Good luck!

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