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#4641926 - 01/21/18 01:11 PM Volvo's PCV system...what's the deal?
Lolvoguy Online   sleepy

Registered: 02/06/14
Posts: 2338
Loc: Canada
By PCV, I'm referring to the Positive Crankcase Ventilation system.

Recently I was on a Volvo forum where someone was asking for a quote on getting the whole system refreshed (new hoses etc.).
This got me thinking, why is Volvo's PCV system so finniky?! Even on the old red block RWD engines from the late 70's the system was overly complex and required more attention than any other car I've owned before, or since.

Is there some benefit to it that I'm not understanding? or is it just another way to ensure Volvo owners will keep visiting their local Volvo service departments?

Just my random Sunday morning thoughts
06 Lexus IS350- Wife
88 BMW 325is- Mistress
03 Suzuki SV650S- One night stand

#4641936 - 01/21/18 01:25 PM Re: Volvo's PCV system...what's the deal? [Re: Lolvoguy]
ARB1977 Offline

Registered: 06/12/05
Posts: 5168
Loc: North Texas
Over engineering. Keeping things simple is a thing of the past.
2015 Tacoma 4.0L 60K (as of 02/23/18)
Amsoil SS 0W30 / Toyota filter

2018 CRV 1.5L (as of 05/11/18)
Factory fill / Factory filter

#4641938 - 01/21/18 01:28 PM Re: Volvo's PCV system...what's the deal? [Re: Lolvoguy]
rooflessVW Online   content

Registered: 12/24/11
Posts: 4050
Loc: North Carolina
Every OEM has at least one "calling card" issue. Volvo's is PCV.
"Zed's dead baby, Zed's dead."

#4641939 - 01/21/18 01:28 PM Re: Volvo's PCV system...what's the deal? [Re: Lolvoguy]
bdcardinal Online   content

Registered: 06/03/05
Posts: 10993
Loc: Santa Barbara, CA
I replaced the heat trap on my S60R, that was an adventure to say the least.
2014 Ford Mustang GT Track Pack
1995 Ford Mustang GT

Ford/Mazda Parts Counter
NRA Benefactor Member
Opinions expressed are my own.

#4641973 - 01/21/18 02:03 PM Re: Volvo's PCV system...what's the deal? [Re: Lolvoguy]
bigjl Offline

Registered: 09/06/12
Posts: 2220
Loc: London, England
I have never heard much about PCV issues with Volvo in the UK.

Even when petrol versions were widely used by the Police and did huge mileages as motorway patrol vehicles I never heard about it from owners of these mega miles cars.

Though the petrols are now rather rare as in the last 15 years or so diesel Volvos are more common than the petrols.

I wonder why they are so problematic in the US?

Edited by bigjl (01/21/18 02:08 PM)
16 S350d LWB 25k Mobil Super 3000 XE 5w30
17 Smart ForFour Auto 6.5k Mobil 1 0w40 FS

#4641977 - 01/21/18 02:10 PM Re: Volvo's PCV system...what's the deal? [Re: Lolvoguy]
PeterPolyol Offline

Registered: 03/06/16
Posts: 1345
Loc: toronto
Wonder what kind of oil is used on those Police cars

#4641978 - 01/21/18 02:11 PM Re: Volvo's PCV system...what's the deal? [Re: bigjl]
Kira Offline

Registered: 08/19/10
Posts: 5242
Loc: Champlain/Hudson Valley
I hope you see oragex's recent "advice post" of his PCV work on either Matthew's or

The "oil drip catch box" of the PCV system has 4 hoses on it. 1)short vacuum source, 2)drip return at the box's bottom, 3)the long one which goes to the base of the filler neck, 4)the other one in the middle.

No big deal.

The trouble is the box is mounted against the block and removal of the intake manifold is required to change out a $220 kit of plastic parts.
That alone is the stupid design.

#4641982 - 01/21/18 02:16 PM Re: Volvo's PCV system...what's the deal? [Re: Lolvoguy]
VeryNoisyPoet Offline

Registered: 12/16/17
Posts: 290
Loc: Massachusetts
They do seem complex and time consuming to service, at least on my '98 model. Forced induction doesn't help, with how it has to vent to gases to the intake manifold when off boost, but vent to the turbo inlet when boost is up. More hoses and valves to get clogged or fail.

That said the first one lasted until almost 150k miles before it plugged. Back then my dad owned it, and he had a shop do the repair. I'm now running synthetic oil, so I'm hoping to not have to replace it again anytime soon (knock on wood).
1998 V70 GLT / 187k miles

"Use yah blinkah!"

"Be nice. The alternative involves an air horn and 7000 lumens of high beam."

#4641985 - 01/21/18 02:19 PM Re: Volvo's PCV system...what's the deal? [Re: Lolvoguy]
sleddriver Offline

Registered: 02/06/10
Posts: 4603
Loc: Central Texas
The sled has never had a port clog during my 20yrs of ownership. I only use synthetic oil. Two repeating problems I've had is that the plastic pipe running below the intake manifold cracks from heat/vibration. When this occurs, there is no longer any vacuum on the catch can and you now have an open, unmetered vacuum leak.

This also causes hot oil vapor/blow-by to not be pulled out of the upper valve cover, causing extensive varnishing.

In later models, these rigid plastic tubes were replaced with aluminum.

Finally, weather plays a huge role in this.
1998 Volvo V70 T5 226,808 mi. Original Owner.
M1 10W-30 HM
"It's never a mistake to buy tools, defined broadly. They're not a cost, they're an investment." - J.B. Peterson

#4642059 - 01/21/18 03:45 PM Re: Volvo's PCV system...what's the deal? [Re: Lolvoguy]
dlundblad Offline

Registered: 09/30/13
Posts: 10037
Loc: Indiana
We did hers about 12k ago. Nothing was clogged, but the flame trap and the line from the top of the engine to the flame trap was getting there much like an artery. Lots of yellow goo in the trap and carbon in the line. Thankfully, the flame trap to the block hole was clear and I didn't have to drop the pan.

Oil consumption has gone down substantially after the replacement. Uses around half a quart during a ~6.5k OCI.

The job was a pain, but I could do it much quicker a second time. Certainly wouldn't keep me from buying another. If the car saw A3/ B4 oil as well as highway miles her whole life, would it have been better? Probably.

Edited by dlundblad (01/21/18 03:46 PM)
03 Jeep WJ 4.0 199k Castrol Edge 10w40 HM Fram XG16
02 Volvo S60 2.4T 177k M1 0w40 Mahle OX149D
97 Chevy Blazer 4.3 145k Rotella T5 10w30 Fram TG3980

#4642149 - 01/21/18 05:34 PM Re: Volvo's PCV system...what's the deal? [Re: Lolvoguy]
Silk Offline

Registered: 07/26/03
Posts: 4562
Loc: New Zealand
It's a good idea (everyone wants a catch can that drains to the sump) but poorly executed. It's hidden away under the inlet manifold, and everything is made out of plastic, which of course gets hard and brittle with age. My pipe under the manifold broke, and used the 5/8 heater hose trick because that's all I had available at the time last year. This year I revisited the system, looking good, no sludge...although there wasn't much last year anyway. I didn't like the idea of a rubber hose, but it's still ok, so eliminated some of the bends, using a right angle at the tank and turbo inlet, and steel pipe under the manifold. So now only short sections of heater hose. I'm going to forget about it now.
1987 BMW R65 - Penrite V Twin 20/50
2005 Nissan Expert - Gulf Western 10W-40
1996 Volvo T5 - Penrite HPR15 - 15W-60. Ryco syntec filter.

#4642231 - 01/21/18 06:39 PM Re: Volvo's PCV system...what's the deal? [Re: Lolvoguy]
Linctex Offline

Registered: 12/31/16
Posts: 6148
Loc: Waco, TX
Sounds like an item that could benefit from a little bit of Berryman's B-12 once in a great while.
"The evidence demands a verdict".
(Re:VOA)"it's nearly impossible to actually know the particular additives that are in there at what concentrations."

#4642293 - 01/21/18 07:35 PM Re: Volvo's PCV system...what's the deal? [Re: PeterPolyol]
bigjl Offline

Registered: 09/06/12
Posts: 2220
Loc: London, England
Originally Posted By: PeterPolyol
Wonder what kind of oil is used on those Police cars

They usually use the oil that is recommended by the manufacturer so I would suspect Castrol.

That is what was the recommended oil in my 08 V50.

5w30 semi synth as a minimum meeting A5/B5 if I remember correctly.
With an OCI of 12.5k if I remember correctly.
If used in harsh conditions, taxi use, Police use, lots of idling etc then the recommendation was still the same OCI but 0w30 Full Synthetic only.

That was for the 2.0d without a DPF.

I can remember what the requirements for the petrols were unfortunately.

Could using dino oil make a difference?

Or would the warmer climate in the majority of the US make a difference?

I have never cleaned or replaced a PCV system in any car that I have owned.

I don't know anybody that has either.

Maybe its down to US owners monitoring oil use more and trying to keep the vehicle optimised throughout the ownership period? I have noticed that US vehicles retain value better than UK ones often.

A 10 yr old car is pretty much worthless in the UK when compared to what an identical car in mainland Europe or the US
16 S350d LWB 25k Mobil Super 3000 XE 5w30
17 Smart ForFour Auto 6.5k Mobil 1 0w40 FS