2003 V70 Squealing Noise Related to Crankcase Vacuum

Post by **chrism** » 04 Jun 2014, 17:38

The car is a 2.4 N/A with 200,000 miles.

I'm getting a squealing noise that sounds exactly like a slipping fan belt, however a new serp belt didn't cure it. Here are the clues:

1.) It only happens after driving for a while and the engine is good and warm.

2.) It's somehow related to crankcase vacuum. When the squealing is happening, the oil filler cap is very difficult to remove. It's REALLY sucked down tight. Once the cap is lifted up, the squealing stops immediately. Screwing the cap back on, the squealing restarts immediately.

3.) The noise seems to emit from somewhere below the #4-#5 intake manifold runners. I have put the stethoscope on everything I can find in that vicinity and can't hit on the source of the noise.

4.) Turn the A/C off and the squealing SLOWLY diminishes. Turn the A/C back on and the squealing SLOWLY returns. (My theory on this part of the puzzle is that that when the A/C is shut off, the reduced engine load translates to a change in idle control which affects the vacuum.)

I've read that there is a vacuum pump that can act up and cause issues something like this. Also, this car is one of those that will occasionally emit a short (1-2 seconds) "buzzing" noise every few seconds after the engine is shut off. Is this related?

Any ideas what might be going on?

Post by **jimmy57** » 04 Jun 2014, 17:54

The crankcase vent box has a crank pressure regulator on top of it. The diaphragm ruptures and it connects manifold vac to the crankcase. Then the cam or crank seals become kazoos.
I don't think anyone services parts of the valve. You have to replace the box

Post by **oragex** » 04 Jun 2014, 19:06

Like jimmy says, when the crankcase ventilation box (PCV) gets gummed up, it has to be replaced, as well as it's hoses. the intake manifold has to came off to have access to the box. once the pcv is removed, oil passages into the engine block need to be inspected for cleanliness or the pcv system cannot work. often times, the oil pan needs to be removed as the oil passages cannot be completely cleaned otherwise.

when the box gets clogged, the engine puts pressure through various engine seals. it's the seals that start 'screaming' because of the pressure going past the seal as the engine warms up. the seals can get ruined. the oil cap being sucked down is typical for this.

one temporary trick to keep things from aggravate, is to drive with the oil dipstick slightly pulled out.

Post by **chrism** » 04 Jun 2014, 19:30

Thanks for the insight.

I've done a PCV service before on the wife's 05 S80 2.5T, so I'm familiar with the procedure to remove the intake manifold, etc. On the S80 I was able to flush the breather box out and reuse it, but it sounds as though I will need to replace the box on this one.

Typically we're always warned about TOO MUCH crankcase pressure blowing the seals out, but if the crankcase pressure is TOO LOW do I still risk that type of damage?

Also, are there any words of wisdom concerning the intermittent "buzzing" I sometimes hear after shut-down. I've read somewhere that there's some sort of control valve that cracks and allows a vacuum leak which in turn prompts the pump to run in order to maintain vacuum at the brake booster. I suspect an intermittent booster leak because I sometimes hear a high pitch whistle under the dash that is silenced by tapping the brake pedal. Could that cause the pump to buzz?

Post by **chrism** » 15 Jun 2014, 09:12

Jmmy57,

Bingo! The oil trap diaphragm was ruptured and the inside of the reglator was quite gunked up. (200,000 miles) Of course I had to crack the old regulator just to see inside. Thanks for the info!

Post by **IdahoBob** » 21 Jun 2014, 23:41

Thanks for the photo!

If anyone is reading this just to get smarter...sometimes you know this fix is in your future because you oil is getting dirty too soon between changes. Also, on the non-turbo 6 cylinder S80, you can do this without removing the intake manifold. Much less space to work though on the 5-cylinder.

Fleursvolvo · Post by **Fleursvolvo** » 17 Oct 2016, 03:26

I have exactly the same problem with my s60 December 2000 build in Belgium.non turbo.i removed the intake manifold,fuel rail etc to get at the oil seperator box with the pcv valve incorporated in it
Dismantling the diaphragm cover revealed a slightly split diaphragm,almost exactly the same as the pics posted previously,it is a very well maintained car.the non return valve to the brake booster from the intake manifold is also not functioning.i am replacing both tomorrow.
The symptoms were very difficult to diagnose by workshop mechanics due to the intermittent effects on the car such as loss of power when warmed up,and occasionally limp home mode on really hot and humid days.30degrees Celsius and 90 %humidity,the worst possible time.live drive time analysys by one mechanic said fuel injectors staying open too long, another code readout from auto pro said misfire on no 2 cylinder but a bit of dismantling has revealed the above issues.
I must note there was no squeeling or crankcase pressure coming up through the oil dipstick, this I think is because the oil seperator box is quite clean,the only sludge was around the diaphragm. The pipes to, and and holes in the block were clear.
Such a small part as the diaphragm can cause a lot of issues and I would like to know if anyone can source a replacement diaphragm instead of purchasing a$160 unit from Volvo.someone must make them.
Thanks to Mathew and all the people who contribute.together we can tame this beast.
I will be posting my results tomorrow. Fingers crossed. I

Post by **chrism** » 17 Oct 2016, 10:39

"...I would like to know if anyone can source a replacement diaphragm instead of purchasing a$160 unit from Volvo...."

Different options available, depending on what all your PCV system needs to get it working properly again:

https://www.fcpeuro.com/products/volvo- ... 70-8642185

https://www.fcpeuro.com/products/volvo- ... 70pcvbase3

https://www.fcpeuro.com/products/volvo- ... aearly1p10

Fleursvolvo · Post by **Fleursvolvo** » 18 Oct 2016, 02:34

Well that wasn't it.
I replaced the oil seperator and non return valve to the brake booster with new Volvo parts and still I get a rough idle when warmed up.the interior lights also flicker slightly, in sync with the revs.
My feelings are that these things needed to be done but there are still more issues.
So Tomorrow I'll book it in for a diagnostics check

Fleursvolvo · Post by **Fleursvolvo** » 18 Oct 2016, 03:43

Stop the press!! I made a mistake. A big mistake!!
In my haste to get it all back together and go for a drive I forgot to put the dipstick tube and dipstick back.
Yes I am the dipstick!!
Loss of vacuum, rough idling,rough drive.
So I replaced the dipstick and tube and went for a drive.
PERFECT. Joy of joys. No light flicking either.
So there it is. True story