I got 1985 740Gle Non-turbo w/ M46.

The overdrive will not engage until it's been warmed up for between ten and 15 minutes. It's been pretty consistant, on the way to work I can gauge just about when it will start to work. Although it does seem to take a little longer as it's been getting cooler here. (OHIO)

It does show signs of a slow leak but does not puddle. Possibly only leaking while engaged? I've tried to tighten all visible nuts.

I have drained and topped up with TYPE F Auto tranny fluid, still does the same thing.

Is it that hard to take off and drain the thing and replace any o-rings and such?

In the FAQ it looks as though everything may fall out if I remove the cover!!

Any ideas on this?

Allow me to drop in a little late. Just getting caught up after a few days off.

Slow to engage how? Does the dash light come on when you push the button but the OD does not react? This is an OD problem, either the solenoids electrical or internal piston problem.

If dash light does not come on until after a period of time, then this is an electrical problem: fuse, wiring, relay or transmission switch problem.

To eliminate the electrical problems, e-mail me for a text file that steps you through a test sequence to isolate any electrical problems. After that, it is an internal OD problem.

Internal OD problem most likely is actuating piston seals, which act just the oposite of your problem discription. With bad internal seals, the OD works better cold than warm.

My bet is on an electrial problem, the 4th gear switch or corroded terminal on the solenoid.

Duane

I have some experience with the M46 from when I was having my own problems, so here it goes:

My first thought upon reading your symptoms was low transmission fluid. You topped it up, though, so that's probably not it. This definitely sounds like a problem with the hydraulics, though. It is possible to take off that inspection plate, beyond which are three plugs. The only thing that falls out when you take off the inspection plate is a rectangular screen...and all the transmission fluid. Behind the big plug, there is a round filter which could be clogged and impeding the flow of fluid. The small, middle plug retains the non-return valve, and the last remaining plug retains the relief valve. (I'm using my Haynes manual to refresh my memory, here, since it's been a while since I was in there.) So if you're willing to take a shot at getting under the car and opening up that inspection plate, you might want to open up those plugs and see that everything is in working order, with good o-rings. Then clean out the filters, button it up with new Type-F, and see how she performs. This may not fix it, but it doesn't cost any money to carry out this inspection, except for a few dollars for more transmission fluid. And if it works, you've done well.

One question: How well dose the OD disengage? Is it quick to come out? Or is it sluggish/hesitant? If disengagement is a problem, you could be looking at a mechanical problem. I might suspect that the cone clutch is hanging up on the long studs on which it rides. I might also be inclined to suspect the solenoid. My solenoid failed, causing a quick engagement but the OD would not disengage. I bought a new solenoid and it's been fine since. But that was the last thing I did...

Before dropping $200 on a solenoid, I worked my way up the cost ladder, (though, not the "time ladder"), and took the OD completely off of the car to install the "mini od rebuild kit" that I bought from IPD. (It was around $50 at the time.) This replaced virtually every o-ring in the unit, and afforded me the opportunity to inspect all mechanical parts. But it was a two day job, and didn't actually fix the problem. (You can probably imagine how disappointed I was.)

So I'll try to sum it up here, with an order of steps that you *might* want to take. 1) Wait for other replies here, as there are many who are more experienced than I am. 2) If you are willing to get a little dirty and are competent with safe use of jackstands, consider taking that inspection plate off and looking at mechanisms behind the three plugs. Keep in mind that you will need a pin spanner to get the plugs off, and you will definitely want a shop manual on hand in case you forget how to put the non-return valve back together. (BTDT) 3) If the OD has some mileage on it and you can afford to have the car off the road for a few days, (and are willing to do this kind of work), consider taking the OD off the car for a full inspection/ installation of new o-rings and seals. (Again, I used the IPD kit.) Personally, this was my first "major" undertaking and it went relatively well. The hardest part is getting the OD on and off the car. It's heavy. 4) If nothing has worked up until this point you probably need to either rebuild your solenoid, or buy a new one. As far as I can tell, there's really nothing left by now. If there is an internal problem, (such as a worn cone clutch), it will become evident during the rebuild.

I know that this post is long already, but I have to add the usual disclaimer: These steps worked for me, but may not necessarily work for you. It's impossible for any of us here to know for sure what will/will not fix any given problem. (Yes, this is just to cover my you-know-what. But I'm sure you understand :)).

Anyway, good luck. I know how aggravating a malfunctioning OD can be, but one that works is a wonderful thing. Let us know how things go.

Tim

Tim,

Thanks, don't mind the long reply. Just what I wanted to see. I definitely don't mind getting hands dirty, just don't want to screw it up!

This sounds similar to hydralic power steering pump on Audi 100 I rebuilt.

Also I have ramps so this shouldn't be problem. It does disengage easily.

I'm hoping that it is just clogged filter

I'll check it out...

Sounds like a plan. Just bear in mind that you have to get the entire car off the ground and level when you're re-filling the fluid. I've never known anyone to do that with ramps, but I'm certainly no expert so I'll leave you to your ways. (Incidentally, I don't suppose there's any chance you had only the back wheels on ramps when you filled the fluid last time is there? I only ask because you mentioned the ramps, and it seems like such a simple mistake that would cause you not to be able to put enough fluid into the tranny. If I'm being ridiculous, I apologize in advance.) Good luck with the procedure. As always, be careful under that car!

If you have more questions, feel free to post them. Let us know how it goes.

Tim

Gee do I feel stupid!!. OF COURSE I HAD ONLY THE FRONT UP IN THE AIR!!!

I think I'll try this again. I'll put the front on the ramps and the back up with a 3 ton trolly jack (and Jackstands of course) THis might be the problem. thanks for mentioning the obvious.

Sounds good, as long as there's no risk that the front wheels are going to start rolling off of the ramps. They spin freely, so there's nothing on the car to stop them from rolling once the rear wheels have been lifted off the ground by the trolley jack. I'd feel better if you were using 4 jackstands, but that's just me. I can live with whatever as long as it's safe. I hope that this is just a case of low fluid. But here's the next question: Where is that leak coming from that you talk about in your original post? In order to truly fix the problem, that has to be taken care of. Good luck.

Tim