98 Vulcan 'rumble' vibration 1100/2000rpm

[amcweeny]

I have this strange 'rumble strip' vibration on my 98 wagon Vulcan engine. As it goes through the 1100rpm and also 2000rpm range (in park or drive) there is a distinct vibration like driving over a highway rumble strip. I've changed the sepentine belt and checked the idller and tension rollers and there's no play in them and they roll smoothly. Any ideas? Could it be the timig chain? Car has 214,000Km on it.

Thanks
Andy

[Millermagic]

Does it do it going down the road?

[amcweeny]

Originally Posted by Millermagic

Does it do it going down the road?

The vibration happens as the engine passes back and forth through these 2 rpm ranges. In park, and in drive as the engine rpms change with the transmission . It's not the transmission or wheel bearings as it happens when the car is stationary. I'm leaning towards changing the belt tensioner as it needed much WD40 to loosen it when I changed the belt and it may not be fully tensioned which could cause the belt and tensioner to resonate at these rpms.
Still looking for other suggestions though.

Andy

[shorod]

Well, don't rule out the transmission yet. Even in park and neutral, parts of the transmission are still rotating. Specifically, the torque converter could be contributing to a vibration such as the one you describe. Have you checked the transmission fluid for signs of being burnt or contaminated? When was the last time the transmission fluid and filter were changed?

You will want to inspect the engine and transmission mounts as well. If you feel a distinct vibration in the car, like what you experience over rumble strips, I would suspect something more massive than a pulley is causing that vibration.

-Rod

[brokenantimatter]

Without giving thought to anything that has been previosuly posted, I would check the motor mounts.

Also do you have the same vibration with OD turned off?