I pretend to know about these things, but I really don't...

216 auto. The box began doing strange things a few months ago. It would stay in 1st/second when driving and a high-pitched whine was heard inside/outside the car. This was road-speed related rather than engine revs related, and the pitch seemed to rise very quickly compared to increase in road speed.

When this first started several months ago, it would correct itself within seconds - now however it's taking 10-15 minutes to fix itself.

By fix, I mean - there's a loud, brief screeching/snapping sound from the engine bay and hey presto - the car has 4 gears again and the box changes up and down them as it should.

Transmission fluid is at max. and is clean.

Someone has mentioned this could be one or more of the gear-actuating solenoids that has gone, but I'm not sure.

Any help appreciated.

Try leaving it in D3 and drive it like that for a while, including high speed trips like on dual carriage ways, also put it in 2 every so often but not above 40mph,

My old 416 was apparently not pulling away in 1st but after doing the above and giving it a good thrashing it now works better than ever.

Have you got the correct hondamatic fluid in the box, because the Honda boxes don't take to kindly to any other fluid

roverman1 wrote: Have you got the correct hondamatic fluid in the box, because the Honda boxes don't take to kindly to any other fluid

In GM speak, it's a Dexron IId spec fluid apparently, and Dexron III is the "superior replacement." I know it's been topped up with Dexron III recently.

You say Honda boxes don't take kindly to anything other than Hondamatic fluid - I'm thinking this wouldn't improve things as they are now. The Dexron III was the fix that prevented the ATF eating seals and other vital components in their gearboxes back in the late 70s... It could very well be something has gotten corroded in the box, but a change to Hondamatic now won't fix that.

Something is spinning up really fast - could it be the rotor/stator combo - i.e. I'm just not getting fluid coupling?

I gave it a run at 4000rpm in D3. But this was after it had snapped back into correct operation. I can't do a cold run in D3 or 2 because I hit heavy traffic whether I leave home or leave work, no matter what time of day.

All this seems to have done is made things worse. I had to put the car into reverse and I got a nice grinding noise for a few seconds, then the gear engaged. I probably won't be doing that again...

Driving in D3 should have no detrimental affect on the car whatsoever, I used to often leave mine in D3 if i was in traffic and while going up steep hills of which there are many where I live I would keep it in 2.

I sounds like sticking clutch plates or worn plates, but if it was worn clutch plates then the car will slip in drive, I have experienced that on an old 216 I had, where going up hill I could plant my foot into the carpet and the car was just crawling along but engine speed was around 3-4k.

As for the grinding noise, I don't know but as I say maybe sticking clutch plates. Best get a specialist to get some advice I think.