I have a 240 1982 with M46 transmission and 320k miles with original transmission. Fluid type F replaced and strainer/filter cleaned every 65k miles more or less.

EVENT

I had to slow down from 60 mph to about 10 mph, shift to 2nd gear, and started accelerating. I heard a violent noise about every 2 second with some effect on the acceleration. I accelerated slowly back to highway speed and have not encountered that problem again after about 200 miles.

I could not understand what was the problem since the U joints and center bearing support are silent and in good shape.

Then later I figured out that maybe the overdrive solonoid was lazy in dis-engaging. The noise every 2 second could match with the od pistons pumping to dis-engage the conical drum, pulsing between od engaged and dis-engaged. Overdrive work normal when stopped, clutch depressed and in 4th gear.

Have brickters encountered problems with M46 overdrive solonoid other than total failure ?

Hi,

Well, you didn't say how fast you had to slow down to ten miles per hour but you stayed in second gear it appears to go back up to highway speed.

The M46, on my 1978, does not have a relay and switch to disconnect the overdrive solenoid.
I have to be sure I always get out of overdrive manually!
A panic stop is to be avoided and so far I have not had that happen!
I have inadvertently left it in though and I catch on to it and feel the slowness.
But then it's a K jet 2.1 Liter and all my other cars have a little more low end power!

You are not supposed to engage the overdrive below 45 mph.
So I would say, yes, there might have been an issue with the overdrive pump putting out enough pressure, at those low of output shaft RPMS, to make the shift back up!
So, the second gear was more like a third gear@10 MPH!
The Lugging through the planetary reduction wasn't a nice thing for the mechanism.
Noise, I bet so very much, it was a low rumbling!

My 1984 and 1986 does have this relay/switch feature.
You are not supposed to engage the overdrive below 45 mph. So I would say there might have been an issue with the overdrive pump putting out pressure at that low of output shaft RPMS to make the shift.

So the question is does the 1982 have that newer relay/transmission switch feature or did it not work in time? I cannot answer?

I can say in that, you are not ever suppose to leave it a lower gear and BACK UP after using the over drive.

The whole overdrive feature is only supposed to be used in fourth gear and that's where the transmission switch feature is located, on it, so you cannot leave the overdrive engaged!

Wait for another response, to if, your car has what?

Phil

If the original poster has an sliding On/Off type switch at the top of the shift knob he has no relay. If his car has the type switch that just requires pushing a spring loaded push button it does have a relay. The Laycock OD is mechanically capable of working in the lower gears (my '74 MGB-GT worked on 3rd and 4th and some cars - Sunbeam Alpine for instance, worked on 2nd, 3rd and 4th). Volvo simply chose to have it operate on only 4th. - Dave

The M46 in 1982 had the relay and push button.

I was 150 miles from home when this happened. I drove easy afterward not to break anything. I was lucky and no noise showed up since. It realy felt something will break if that kept going.

Thinking about what caused that noise I could only end up with an overdrive solonoid that did not fully move in the off position. Mechanical or electric problem may be.

Lately I had to replace the overdrive rotten wire that connect on the transmission 4th gear switch. Now I also need to replace the backup switch wires. I will at the same time put a new wire from the solonoid to the relay. I might find something bad in there.

Just wonder if something similar happened to someone else.

Thanks for your input.