Tapping noise during acceleration on 1998 Volvo S70 GLT

jeovaz · Post by **jeovaz** » 28 May 2007, 15:52

akitawagon wrote:I'm not sure if my issue is the same as yours, but I had a fairly loud tapping/fluttering/ratcheting noise (almost sounded like a mechanical problem) that occurred when giving gas for accelerating or climbing hills.

I thought it might have been an exhaust leak, but turned out to be that one of the elbows attached to the vacuum tree by the IAC valve had cracked at a bend that wasn't visible until I removed the vacuum tree for cleaning out the throttle. Fixing the bad elbow seems to have eliminated the tapping/fluttering noise and my car feels like it's gained some of its low end torque back.

Where is this cracked elbow located? Totally new to Volvo and am not yet familiar with the terms.

Post by **akitawagon** » 29 May 2007, 17:24

Hi jeovaz,

If you you remove the black plastic cover over the throttle that is held down by one torx 25 or 30 screw, you will see the Idle Air Control Valve (IAC) and behind it is a vacuum tree with multiple ports. One of the hard vacuum lines with the rubber elbow had a big crack in the inside bend of the elbow.

I'll try to take some pictures tonight if I can. My reason for the "single Britax modification" may keep me busy for a while...

BTW, I've been able to drive and push the car a bit harder over the past couple of days, and while the noise is still kind of there, it is not as loud as before. So... I'll be eventually replacing all my vacuum lines with silicon lines.

MadeInAmerica · Post by **MadeInAmerica** » 29 May 2007, 17:55

Vacuum tree pic '94 850 Turbo

jeovaz · Post by **jeovaz** » 01 Jun 2007, 09:07

Thanks for the picture and help akita. I checked mine and my connectors are are all intact as well as the tubing. I'm still hearing the noise.

It may not be a lifter noise... I kinda notice that the noise is kicks in with the turbo, which could be exhaust related.

BTW, the picture you posted confirmed that I am missing an air intake tube from the top of the radiator to the bottom of the fileter box. the former owner probably missed to put it back. Right now I palced an Al duct to get some colder air into the intake.

Thanks again for the help.