Volvo 940 rattle

[cmblackburn]

Hey all, I have a friend with a Volvo 940 sedan that's got a problem. He's got 208,000 miles- and whenever his car is at idle in drive it rattles like crazy. I'm not very sure where the mounts are on a red block... But I believe that might be why. Is that a common problem on a 940? It has a horrible rattle coming from underneath... I believe it to be the exhaust. What should I check?
It's worth mentioning there is no CEL but it runs kind of rough. He has no idea when the spark plugs were last changed so I told him that would be a good place to start. The timing belt was changed at 201,000 miles.
If anyone has any suggestions, please let me know. Thanks!

[precopster]

Well almost every rear drive car I've owned has needed a transmission mount and yes I did get a awful rattle when in gear. In the 740 turbo the trans was contacting the exhaust.

It particularly is needed when leaking from the output shaft has occurred and the rubber in the mount has softened and degraded. There's a trans bush made of softer metal in the rear extension housing which can cause slop in the seal and if not replaced will just result in chewed seals every few thousand miles. The rear mount is housed in a crossmember running under the front seats.

Not a big job if you have a hoist but really hard to access all the rear extension housing bolts while lying underneath with a jack holding up the trans. Around 2 hours of shop time and about $50 of parts.

Yep, spark plugs could be worn but rattling isn't common on these unless they're idling too low. Another thing to check would be that the microswitch on the throttle is contacted and you hear a click on throttle return (motor can be off to check this)
A simple adjustment of the idle stop screw fixes this.

[Kirby J]

Check the tensioner on the timing belt. It will rattle like a can full of rocks.

Kirby J