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Discussion Starter · #1 ·
My XC90 experience an extremely worrisome incident today that disappeared after I turned the vehicle off and let it sit for 5 minutes.

I was coming into Baltimore waiting at a red light after just exiting the highway, when I heard this eerie whine coming from inside the engine bay. It sounded much like the artificial emitter tone electric cars are now required to use when traveling at low speed.

Subsequently, I rolled the window down to confirm that this was my car - which it was. I know what a slipping belt sounds like and this wasn’t that. They tone was far more metallic. While stopped, I thought maybe transmission, so I ran the gear shifter through the drive settings which did nothing.

Next I put the truck in N and gave the throttle a blip - and this was the first big red flag; the engine revved, but didn’t settle - it dipped then went back UP! Around 2000rpm or so for about 2 seconds with my foot off the accelerator. I felt a few power pulses then it dropped. The whine pitch didn’t change throughout.

I repeated the problem - blip, foot off accelerator, RPMs wobble, rise and hang, then dropped. By now the light turned green. I slipped the car into Drive and gently pulled off. I was met by with a scary rattle from the engine, during roll off and load and lumpy, reduced power - almost like I lost a cylinder.

I immediately think I’ve killed the engine! I pulled over and checked the oil. Oil was a little low but well within limits. Full synth, 6000 miles on it and the filter, so, it’s due for a change in 1000-1500.

I checked the vehicle info screen - no warnings or messages. No warning triangle. Nothing.

I let the truck rest for about 5 minutes, started it back up and now everything appears to be fine but obviously I find this highly disconcerting. Anyone have any idea what just happened?
 

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Hey, I was just in Baltimore this afternoon too and pulled off I95 without a htich.

As generic_volvo_driver mentioned, check the PCV if it is making any vacuum or whining noise.

Sometimes a failing crankshaft position sensor can start to alter its signal when hot. Waiting for the sensor to cool can help bring it back to sending the right signal, but it is still a failing sensor. If you can, check the codes with VIDA to see if there are any stored codes which would indicate this condition and there might not be a message on the dash because the computer was simply adjusting the parameters with the input signal. If the crankshaft position sensor is bad, then it could throw off the timing, fuel, and variable valve timing. You just might have to check a running signal if it happens again to determine if it is the culprit. The metallic whine could be poor combustion rattling the exhaust or poor running vibrating a different part (heatshield, exhaust, etc.)

Another culprit could be the fuel pump going bad and what you are hearing is the pump whine. This too could be affected by heat (not sure if you spent the more than hour driving to Baltimore and if your fuel level was full). Check codes to see if there were any signs of fuel pressure related issues it detected, but if the duration of a fuel pressure issue was not long enough, then it might not have displayed in the messages yet.

The theme is to check the codes with VIDA to see if there are any stored codes that could narrow the possiblities. Some other issues could be electric fan, drag with the A/C clutch, etc.
 

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Discussion Starter · #4 · (Edited)
First video is almost exactly what it sounded like, however, the sound seemed to emanate from down by the accessory drive side.
Oddly enough, out of instinct I opened the oil fill cap while the engine was on but did not hear the "Psssht" vacuum pressure release as heard in the video.
I'll have to try it again tonight when I get home.

I can't recall whether I checked the oil with the engine on or off. Probably off.

Would a failing PCV also cause the other symptoms?
 

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Discussion Starter · #5 ·
Hey, I was just in Baltimore this afternoon too and pulled off I95 without a htich.

As generic_volvo_driver mentioned, check the PCV if it is making any vacuum or whining noise.

Sometimes a failing crankshaft position sensor can start to alter its signal when hot. Waiting for the sensor to cool can help bring it back to sending the right signal, but it is still a failing sensor. If you can, check the codes with VIDA to see if there are any stored codes which would indicate this condition and there might not be a message on the dash because the computer was simply adjusting the parameters with the input signal. If the crankshaft position sensor is bad, then it could throw off the timing, fuel, and variable valve timing. You just might have to check a running signal if it happens again to determine if it is the culprit. The metallic whine could be poor combustion rattling the exhaust or poor running vibrating a different part (heatshield, exhaust, etc.)

Another culprit could be the fuel pump going bad and what you are hearing is the pump whine. This too could be affected by heat (not sure if you spent the more than hour driving to Baltimore and if your fuel level was full). Check codes to see if there were any signs of fuel pressure related issues it detected, but if the duration of a fuel pressure issue was not long enough, then it might not have displayed in the messages yet.

The theme is to check the codes with VIDA to see if there are any stored codes that could narrow the possiblities. Some other issues could be electric fan, drag with the A/C clutch, etc.
Thanks for the insight. I'll keep all of these in mind. Looks like a trip to a servicer with VIDA is in my near future.

Out of curiosity, is your XC Black? No trim level emblems only the model? If so, I was directly behind you while stuck in traffic headed South on Light St. toward Pratt around 5pm.
 

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Thanks for the insight. I'll keep all of these in mind. Looks like a trip to a servicer with VIDA is in my near future.

Out of curiosity, is your XC Black? No trim level emblems only the model? If so, I was directly behind you while stuck in traffic headed South on Light St. toward Pratt around 5pm.
You can also check for the high pitched PCV whistle by pulling the dip stick tube.

My XC90 is a shadow blue metallic color with an Illinois license plate. It can look bluish-green or bluish-gray, depending on the light and how clean it is. I am in Montgomery County and have VIDA.


 

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Discussion Starter · #7 ·
I found a Swedish specialist in Laurel but their foremost focus appears to be Saab.
Seems like all the Volvo specialists are in Mo County. Do you deal with any of them? If so, care to recommend one?
I also have to get my ABLs to either reset or return to straight after thumping a deer (they’re both frozen pointing full left), so a trip to a technician is in my future.
 

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I haven't used any independent Volvo shop since I do almost all of my own work. Only time I brought my XC90 into shops are for alignments, tires, and center resonator welding.

However, after my research these are the 2 options I saw.
This place documented their repair for the READ and has a group of Volvo loaner cars: https://www.scottsautomotivemd.com/
This place seems professional, but their prices might also reflect that. I see them more like the dealer techs with their dealer thinking moved here: https://cars.scandinavianimports.com/
 

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Discussion Starter · #9 ·
Thanks. I'll look into both of those.
For what it's worth (in case anyone else from MD ever finds this thread in archives), this was the mechanic shop I found in Laurel:
https://www.facebook.com/DannemansAutoService/ http://dannemanauto.com/
They're right across the street from the Camden MARC station which makes transit very easy if they need to keep the truck for a day or several.
 

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Discussion Starter · #10 ·
Same issue happened again tonight. Although much less pronounced and without the mechanical stuttering drama - just the noise.
Pulled, opened the hood and pulled out the dipstick. Got the telltale "Psssthsssst" noise from the dipstick tube followed by an immediate drop of the whistle noise.

I guess this confirms that it's the PCV. Anyone know what the repair cost has been on average?
 

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Follow the videos I posted and you can fix this in under 20 min. It's a very simple fix!
 

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Discussion Starter · #13 · (Edited)
Follow the videos I posted and you can fix this in under 20 min. It's a very simple fix!
Thanks. I was coming back to update. I woke up this morning and began researching forgetting you had posted links ...

I went on a quick emotional roller coaster:

First I found FCP Euro's video for the 3.2, watched it and said, "Ah fawck! Splice hoses, remove the throttle body and manifold! 2-3 hours of labor. Dammit!"
https://www.youtube.com/watch?v=oEOzIoVxO4s

Then I found this version specific to the XC90 and laughed. :p
It's, as you said, a 20 minute job if you're good with a wrench and prep correctly. No more than 45 minutes even if you're a klutz under hood. 8 bolts right on top of the engine in an easy reach location. Pop off old part, clean up mating surface, put on new part, tighten in star formation. Best part is I'm already in my oil change window. They recommend doing this after replacing the PCV, so the timing is fortuitous - well, as fortuitous as having a screaming tea kettle for an engine can be.
 

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Discussion Starter · #14 ·
Sidenote: While not advisable to drive with this issue, several videos said to pull the dipstick up past the sealed seated point if you still need to drive.
This will help relieve the excess vacuum pressure and prevent blowing out your cam and crankshaft seals.
 

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Good work on checking the dip stick and diagnosing yourself. This job should really be preventative for the 3.2 rather than wait until the diaphragm issue occurs. Many new cars have a diaphragm for their PCV integrated into the valve cover and they also have been wearing out between 80-130k miles.

Like was said, 20 min job. Make sure to clean the area surrounding the PCV as possible before removing the old PCV so dirt doesn't get inside the engine. Don't overtighten and tighten in steps, so a little for each bolt, then go back and tighten more. This will ensure the new seal will sit flush and flat.

It couldn't get any easier, unlike the big job for the 2.5t.
 

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Discussion Starter · #16 ·
Part is on order.
$158 included tax and shipping. OE replacement. I found the same part non-OE/OEM for as $66 on Amazon but who knows what the quality factor may be. Rather not shop on price alone when it comes to critical engine components.
That is not to say that I will ignore price. The local Volvo dealership wanted $325! So much for supporting local business. Get real, guys!

I'm almost tempted to get the Makita out and drill a very small 1/16th hole in the top of the valve cover to see if that temporarily help release the excess vacuum pressure vs. driving with the dipstick pulled up a bit.
 

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Discussion Starter · #17 · (Edited)
About a 55 minute job.
15 of that spent cleaning up the sludge and crud deposits in the pan.
Definitely slowed because my T-30 torx bit was from a screwdriver set and I had to jerryrig a socket to hold the bit (loosely) in an extension socket in order to reach the 4 rear bolts.

 
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