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Checking and replacing PCV

4K views 24 replies 10 participants last post by  thaxman 
#1 ·
I have a 07 XC70. How do I check if it need a new PCV system? And how hard is it to replace?
 
#2 ·
The old test and still pretty valid today. Is to removed the oil cap on the valve cover while the engine is running, While doing that place your hand or a rubber glove over the oil cap hole and see if vaccum is there. If you feel pressure coming out of the oil fill hole or see the rubber glove try to inflate, than chances are your pcv system is clogged or close to it. About every 100k is a good time to replace the pcv flame trap and hoses and also check the pcv oil galleys for blockage.
 
#3 ·
Don't use your hand unless you want to get burned. You need to do this after a decently long drive and leave the engine running. It will be hot. Use a glove. You want to see the engine slowly try and suck the glove in. If it doesn't then it's time to replace the entire PCV system.

It's not easy but not impossible. For a first timer it will be about a 5 or 6 hour job.
 
#5 ·
That's what we like to hear! Check around the time of every oil change that way when it gets clogged, you can catch it before it does serious damage.
 
#6 ·
The more frequent (4-5K miles) oil changes you do WITH SYNTHETIC OIL, the less likely the breather becomes clogged.
Not posting your miles doesn't help.
At 100K you WILL have at least partial blocking
 
#8 ·
we bought a 2004 XC70 in august 2013 with 92000 miles. There were no leaks with conventional oil changed at 7500 miles, records back 7 years. Some deposits and varnish under the oil cap. I changed to synthetic oil. Now on my second synthetic oil change, still no leaks and the varnish is being reduced. i also changed the other fluids and timing belt. PCV is still ok with negative pressure. Perhaps try a synethic blend like Maxlife. I don't plan to exceed 5000 miles on synethic oil.
 
#9 ·
Why would you go back
Use FULL synthetic only and you also may want to Seafoam it before your next oil change
 
#25 ·
Very very old info. Engine tolerances have changed DRASTICALLY since the 80s when full synth first came out. Nowadays unless the engine is about to blow its rings you should not have to worry about synth doing bad things. All around its a better product. It doesn't break down as quickly as dino oil does, so you get more useful life out of it and most importantly, more and better protection. I switched my 1996 Ram truck over when it was over 10 year old and had 165K on the clock. The old 5.2L engine is the same basic beast put in Dodges in 1974 and even that engine with its loose tolerances only saw improvement with synthetic oil.

Also, as JRL stated, do a Seafoam treatment about 100 miles before you plan an oil change. Just follow the instructions on the bottle and be prepared to be worried because the special-effects are video-worthy.
 
#11 ·
I have been using synthetic oil for years in everything. I was suggesting to the OP to try Maxlife which is a blend.

My 20+ year old cub cadet gets Mobile 1. A few years ago the head gasket started to leak compression, no oil leak. I completely disassembled the engine to check rings due to carbon in compustion chamber. The engine was spotless. Now when I see cub cadet engine parts on ebay, I realize the carbon in mine was nothing. The head gasket leak was due to a known head bolt problem on that vintage Kohler engine.

The Volvos, Lincoln and even the Honda gets synthetic. I stash oil and filters when I find good sale prices.
 
#14 ·
Replace the system now. When it clogs, and it will (our 2005 XC70 did at 110K) it will cause so many intermittent problems that you will be chasing your tail for weeks. Codes will indicate things are wrong with components then you change them and maybe it works for two days or maybe it throws another code on the way home from the shop. The book for my car says it should be done at 90k. I wish I read the book. It would have saved some money!

Rich
 
#15 ·
Mobile is a phone

MOBIL is an oil

Guys, get this right
 
#17 ·
That too.
Plenty of nouns and adjectives for the word MOBILE but there's only ONE for MOBIL and that is the oil.

I can't believe how many people spell it this way after looking at their own bottles....how many times?!
 
#19 ·
I took an oil cap and drilled a hole straight through the metal center portion, and through the plastic top. Then I pushed a piece of 1/8" DOT air brake tubing through so I could hook up a guage. The plastic tubing is very ridgid and has a real snug fit for a perfect seal.
Then I took my Dwyer digital manometer with a +/- range of .995 kpa and hooked it up to the following cars (hot) with the following results.
98 S70 T5 138,000 miles.....complete breather job at 90,000 miles -.23 to -.26 kpa at idle
01 V70 T5 136,000 miles....original breather system -.05 to -.07 kpa at idle
Anyone know Volvo's spec in kpa's? The 2001 V70 probably should get a breather job this summer while its still in the negitive column!
 
#20 ·
I measured the crankcase pressure at dipstick tube for our 2004 XC70, at ~ 93000 miles. At idle -0.8" water (-0.20kpa), at > 2000 rpm in neutral more than -1.0" water (-0.25 kpa). I believe the PCV system is original based on the clamps on the box, hoses. The XC was purchased in Aug 2013 with service documentation from 44,000 miles. No record of a PCV change. I have not been successful in determining the target or pass/fail crankcase pressure.
 
#21 ·
This seems to vary from car to car (holy threadbump, batman!). My 2006 with 109700 miles on it didn't need a PCV service and the guy didn't use synthetic oil. I changed it as a matter of routine, but all the parts were clean.

The two things that seem to matter is running the car hot each time you drive it (previous owner had an 80 mile r/t commute) and oil change intervals (he also did that every 3000 miles).

I wish I could drill the little 90 degree bend under the separator box and look into it every 10K miles. That's where the sludge seems to come to rest.
 
#24 ·
This seems to vary from car to car (holy threadbump, batman!). My 2006 with 109700 miles on it didn't need a PCV service and the guy didn't use synthetic oil. I changed it as a matter of routine, but all the parts were clean.

The two things that seem to matter is running the car hot each time you drive it (previous owner had an 80 mile r/t commute) and oil change intervals (he also did that every 3000 miles).

I wish I could drill the little 90 degree bend under the separator box and look into it every 10K miles. That's where the sludge seems to come to rest.
Definitely possible that your PCV was still making vacuum but did you check for vacuum before you pulled it or are you saying it didn't need to be replaced based on looking at the ports?

Highway miles are much better on the PCV system than stop and go or mixed driving. I do a lot of mixed driving but not many trips shorter than 20-30 mins. Mine clogged to the point of blowing out my front crank seal at around 90k miles. My car only got full or blended synth and 5k to 7.5k OCIs.

Ever since it gets only full synth and 5k OCIs.

I'd rather replace the PCV sytem too soon than too late! ;)
 
#23 ·
I wouldn't do it. You don't want little bits of sludge falling down into the oil pan and clogging up the screen of your oil pickup tube.
 
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