Strange noise on startup in cold weather

[pgill]

MVS Readers,

I came across a very interesting video on you tube

The creator VOLVOSWEDEN has a lot of great videos

In the video at 1:24 he starts his 3.0T and it is making a strange sound

Questions (Since its my post I am going to reply first with my guess)

1. Does this sound mechanical to you?

2. What is the most likely source of the strange sound?

3. How can this be confirmed?

4. What is the second most likely source?

5. How can this be confirmed?




I look forward to what others think

Thanks

Paul

[pgill]

Here is my guess

1. Does this sound mechanical to you? Yes

2. What is the most likely source of the strange sound? The PCV diaphragm is the most likely source of the noise, Note: a leaking O-ring on the oil fill cap or dipstick tube may be contributing to the noise.

3. How can this be confirmed? Remove the Oil fill cap and see if the noise changes

4. What is the second most likely source? A bearing for the idler or tensioner pulley

5. How can this be confirmed? Replace the pulleys and see if the noise is eliminated

[pbierre]

1. Does this sound mechanical to you? YES, YOU CAN HEAR THE FREQUENCY COME DOWN WITH THE RPMS. LET'S TRY SOME FREQUENCY ANALYSIS.
ON THE KEYBOARD, THE NOTE WE'RE HEARING IS A "G" ABOVE 440-A, or 785 Hz. That frequency is NOT related to any multiple of the crankshaft 26.6 Hz, or firing rate 160 Hz.

2. What is the most likely source of the strange sound? I'M GOING TO GUESS IT'S THE ACCESSORY BELT, WHICH IS SO RIGID AND TAUT IT SINGS LIKE A VIOLIN STRING. THIS IS SUPPORTED BY THE PITCH FOLLOWING THE RPM AS IT DECREASES, AND THE SOUND GOING AWAY ABOVE A CERTAIN TEMPERATURE.

3. How can this be confirmed? HMM.. I"M GUESSING THAT IF YOU TRY TO HAND-CRANK THE BELT (READ) BACKWARDS, IT WILL PUT UP BIG RESISTANCE....IT WILL WANT TO RETAIN ITS "FROZEN" SHAPE.

WHILE "SINGING", YOU COULD PROBE WITH A CELL PHONE dB METER APP ( OR VOICE MEMO WHICH DISPLAYS WAVEFORM) TO SEE IF THE SOUND IS COMING FROM THE BELT.

SCIENCE GEEKS: STROBE-LAMP THE BELT AT 785 HZ...YOU"LL SLOW-MO THE VIBRATORY MOTION.

4. What is the second most likely source? A SAX SOLO WITH SUSTAINED "G"??

5. How can this be confirmed? TURN DOWN STEREO!!

[pgill]

PBIERRE,

I like the plan to look at the frequency of the sound.

But I’m not going to Canada in the middle of the winter to make the measurement.


Looking at the comments below the video it looks like the power steering pump could also be a source of the noise.

The viscosity of Pentosin CHF 202 is very high

Switching to Pentosin CHF 11S would drop the viscosity at extremely cold temperatures


And the filter screen in the bottom of the reservoir can get clogged and create a restriction that restricts flow.


If I get a chance I will record the sound my 3.2 makes with the oil cap removed, the sound is strangely mechanical


One question is the sound from the video similar to the sound that your T6 makes?

[xHeart]

1. Does this sound mechanical to you?

I do get the low-whistle in our 3.2 when left on driveway overnight during extreme cold temps -- it goes away shortly after. NOT if parked in our heated garage.

The belt, pulley, tensioner, water pump, steering pump, and fluids (all Volvo) were replaced during the 150,000 miles maintenance. More here viewtopic.php?f=10&t=90085.

The oil and filer change was recent (60 days), Pennzoil EURO 5w40.

I'll pull the dipstick before starting to confirm if it is the crankcase vent valve.

[pbierre]

I have serious concerns about the substitution of plastic parts for metal on engines. Add -30F to that equation, and I would cringe just pressing the "START" button.

[xHeart]

The morning temps were hovering 10ºF this weekend. The whinging noise after the engine start was absent.

[pgill]

Xheart,

I started and idled my S80 3.2 and LR2 3.2 yesterday (to confirm cooling fan function) and I checked to see if my PCV was making noise.

Note: It isn't cold here possibly high 40s or low 50s for the low

For both of my 3.2 a noticeable noise was present when I removed the oil fill cap or dip stick tube. (before removing the cap the engine was quiet)

Once the engine warmed up the noise disappeared, even with the fill cap removed.

If the O-ring for the oil fill cap doesn't seal well when it gets cold then the noise would be present without removing the cap.

I did swap the fill cap from my LR2 to the S80 because I've changed the O-ring on the LR2 and I bought a new O-ring so that both of my 3.2s would be nicely sealed.

Take care

Paul

[xHeart]

This is a fairly common problem in extremely cold climates. Water vapor and oil mix together and freeze forming the white creamy frozen gel.

The solution is to drive the car at operating temperature for long enough that the frozen gel does not form. Short trips don't permit the engine and all related systems to get hot enough.

So if you do a bunch of short trips in extreme cold the risk of problems is very high. Drive the car every few trips long enough to get it plenty hot. The heat will keep the gel from forming and break down any that has formed.

In the BMW world on some of there older models, more so than the Volvo world, the frozen gel would actually form a plug which resulted in the system dumping all of the oil into the engine - destroying a number of the engines completely.

^ Found above info relevant to our driving.

In our situation, the noise was only present when the car was parked overnight on our driveway; i.e. absent when parked in our heated garage.

Worth checking at the next opportunity.