01 V70 XC: Odd grinding/pulsing burst sound on right turns. Bonus idle question.

Post by **benpineapple** » 02 Mar 2020, 22:19

https://www.youtube.com/watch?v=KSy3-M-WkzU

*edit: video link above is a example of the sound the car makes on right hand turns every time, without exception.

Hello hello! My partner's 2001 V70 XC AWD has been having a super strange grinding/pulsing issue lately. It only happens on right hand turns, when the wheel gets cranked past 3 o'clock, and at speeds between like ~10 and ~25 (wouldn't be cranking harder than 3 o'clock faster than 25mph anyway).

The sound almost sounds like a grinding servo motor or something, my first thought is maybe it's a bad ABS unit or sensor on that side? I really am at a loss, I have never heard anything quite like this.

This issue first started maybe 2 or 3 weeks ago, and in the past week as it has gotten worse, the grinding bursts have gotten shorter and more frequent. 2 weeks ago it would be one long burst, now it's multiple short ones. What do you think might be going on? I'm truly at a loss. No CEL or ABS light has been kicked.

Other bonus question: ever since getting this "mechanic's special" last summer (I've done LOTS of work on it so far) the idle has always been pretty low, like at stop or in neutral it idles right around ~750, and will dip even lower than that while breaking right before coming to a complete stop. My old '98 V70 would idle right around 850-900 consistently. But this V70 XC seems to vibrate a bit at such a low idle. Where should I look? Again no CEL on this, no banked codes. I'm thinking TPS? Or maybe I should just pull the TB and give it a good cleaning? No idea where to start with it.

Thank you in advance! Let me know if you have any questions or need further clarifications.

Post by **abscate** » 03 Mar 2020, 01:12

Make sure the m8 14mm hex wheel hub bolt is torqued to specs. If it is loose it will trigger ABS

The dip on rundown is classic symptom of a vacuum leak, so check all those hoses with a VAT; visual audible tactile inspection...or smoke test it.

The turbo 2001buses the sexy Itslian throttle body which needs cleaning every 50k or so, and lives for about 150k before saying , Caio!

Post by **benpineapple** » 03 Mar 2020, 11:24

abscate wrote: ↑03 Mar 2020, 01:12 Make sure the m8 14mm hex wheel hub bolt is torqued to specs. If it is loose it will trigger ABS

The dip on rundown is classic symptom of a vacuum leak, so check all those hoses with a VAT; visual audible tactile inspection...or smoke test it.

The turbo 2001buses the sexy Itslian throttle body which needs cleaning every 50k or so, and lives for about 150k before saying , Caio!

Thanks abscate! I think you're totally right it's the ABS firing. It's odd, because it's a totally different sound than when ABS kicks in on ice or something. So as I was driving it a bit ago, I applied the brakes while turning (was 2-footing the pedals), and no ABS was triggered. Did probably 15 right hand turns this morning while applying breaks, 0 ABS triggers. I'm going to pop that wheel off and get the wheel hub bolt tightened and check all ABS connections on that side.

Thanks for the heads up on vac leak. I'll dig into it. Replaced as many vac lines as I could after buying the car last July, I mist have missed a few. I should have cleaned the TB when I did the PCV replacement...My loss. Good to know about the lifespan of those throttle bodies, I had thought it was only the 99 (first electronic TB year) and 00s that had problematic throttle bodies.

Thanks as always! I'll report back on what I find when I dig into these items.

Post by **abscate** » 03 Mar 2020, 11:41

There is a sticky in the ETM Forum with title

“ETM,,,,which models have it?” Or something like that

It infected some models all the way up to 2004

reverend · Post by **reverend** » 03 Mar 2020, 15:01

Make sure it's not just the dust shield that's rubbing on the rotor. It's common enough to squeak or grind and sounding like something is horribly wrong when it's just a quick reach-in-with-your-hands-and-bend-it-away-from-the-rotor fix.

Post by **benpineapple** » 04 Mar 2020, 11:11

Update:

abscate: the 14mm axle bolt wasn't loose. I pulled it and put it off, tightened to factory spec (25ft/lb, then 90deg). Also pulled the ABS sensor on the front left wheel, and the tip looks like it has some grooves rubbed into the tip. I'm thinking something got stuck in there, caused the grooves, and now it's not working properly? Other than that I'm not sure where else to look.

reverend: While I had the wheel off, I did take a look at the dust shield. It looked good, wasn't loose or damaged or close to the rotor. Didn't think it would be something like that, since the sound I'm hearing from DS front side sounds more like a servo pulsing or something like that.