Hello...I replaced the timing belt on 740GL in December. I noticed then that the rubber in the crank pulley was dried and cracked. I also noticed on the bottom gear the "key-way" was partially sheared away. But alas, it was cold and I was poor and put it together anyway.

Since then, it has run fine until recently. I checked the timing and it's about 7-8 degrees. I tried to advance the distributor but it didn't change, no matter where I moved it.

Why would this happen and do I need to replace the pulley and the bottom gear? The engine feels as if it's "missing" at a curbside idle or could it be something else?

Thank you reading this...

Rascol

Your ignition timing is determined electronically, through a flywheel position sensor. A failing keyway will affect timing, since the valves are not in synch with the crankshaft position sensor and the firing of the plugs. Sounds like you should take it apart and fix it right.

In other words, you can't change the timing by rotating the distributor.

--
Matt L. -- Cary, NC -- '91 740 wagon

That is correct...The timing mark does not move no matter how much I move the distributor.

Why would this be?

Because the timing is controlled by the computer. There is no ignition control sensor/switch/pickup coil in the distributor. When you turn the distributor housing you are just changing where on the rotor and cap terminals the spark is jumping to/from. It is not changing when the spark is occuring. I hope this helps.

The only way you could change timing would be to move the engine speed sensor along the bellhousing somehow. And Volvo doesn't want you doing that....
It's a crank=triggered system from 89-on, as opposed to the more conventional distributor mounted pickup the pre-89 cars have.

Rob Bareiss, New London, CT 86 244, 87 244, 88 744 (all old skool!)