940 Auto - flywheel/flex plate issues

[Dave Munro]

Does anyone out there have any experience of flex plate bolts breaking or falling out?

Yesterday, while accelerating away from lights, I heard a clattering noise from under the bonnet. This was followed by a missfire (tacho jumping all over the place) in the 1500 - 2000 rpm range.
I stopped the car and had a good look, but could not see anything.
On restarting, it idled perfectly, with no noises.

Increasing the revs to the aforementioned range brought back the the misfire.
Increasing the revs further and the misfire went away but the clattering started - not all the time, but definately there.

I managed to get home and take another good look and listen.
Reading the codes gave me 2-1-4, which indicates "intermittant rpm sensor", which would explian the misfire. In another document this code also lists "flex plate problem".

I am wondering if I a bolt has broken, or dropped out and is rattling around inside the housing? Or maybe there is a problem witht he flex plate itself.
Car has done 214,000 miles and has been running beautifully until this happened.

[treehorndogsbody]

It is more likely to be the flex plate that has cracked rather than a bolt sheared. I have only ever had one flex plate crack in the 35 years I have been driving automatic cars and that was on a British Leyland Princess, the one like a wedge. That was caused by the pump/input bearing being badly worn and letting things move about. Has the starter motor come loose? All other problems I have had with flex plates have been worn or damaged ring gears.

[fowlerman]

A friend of mine had exactly the same rattling on his 740 when pulling away. It was the flex-plate cracking up. As soon as the volvo independant heard it he knew exactly what it was. He said although it's not a common problem, he had come across it occasionally, and he did in fact have a couple of good s/h plates in stock off cars he had broken for spares.

Pete