This is not a problem more than a question. Whenever I crank my '91 240, the speedo needle gives a little bounce and then goes back down. The car starts easily, then runs fine and the speedo works as it should.

Anybody have any ideas why this occurs?

Thanks as always for any proferred wisdom.

someguyfromMaryland

I have noticed a very similar thing happen in my 87. It doesn't do it every crank but occasionally it does bounce like you say. i have also noticed it happen when the car rolls back a little when I take my food of the brake at a stop light. I would be curious to know the reason too. I think it might be happening more frequently than it used to.

Hmmm. I never noticed that. But I hardly ever drive the later 240s we have with electronic speedos and when I do there's always someone else in the car so I most likely wouldn't pay attention.

If it does that on all of them, I'd guess the chip that converts the pulse rate from the differential mounted pickup drives the analog speedo momentarily on power up, and no one bothered suppressing that glitch in the design.

If yours is not typical, I have no idea at all.
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Art Benstein near Baltimore

Mine does it too - 93 with LH 2.4.
I assume it's some sort of power surge associated with the special electrical circumstances on start-up. Computer powered up, heavy starter drain suddenly released, etc.
Conversely, the tachometer stays firmly at zero rpm when cranking, and only reads once the engine has fired.

Mine does it occasionally as well, but I've noticed something else about it. When I first got my car, it had a real starting problem that I cleared up somewhere between cleaning the throttle body, replacing the flame trap, replacing some vacuum hoses, and replacing the TPS. I don't know which one did it, the car starts like a champ now, but before I'd have to hold the throttle open for up to 30 seconds before the car would decide to idle. If I didn't do that, and allowed it to die, sometimes the speedometer would jump for the entire period until I restarted the car, and the odometer would register as well. I once watched it add a half-mile to the odometer in about 15 seconds.
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1991 245, 61k miles, looking for a 5 speed 92-93 245 cheap.

If that'd happened to me I'd jump to the conclusion my ignition secondary was leaky enough to induce (couple) pulses into the cabling that connects the differential sender to the cluster. Like an open or loose coil wire or rotor with a burned out resistor. Probably would have been heard in the radio too. Interesting introduction to a car.

But then someone wiser than I said "...jumping to conclusions is the only exercise I get anymore."
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Art Benstein near Baltimore