2000 V70 XC Excessive Crankcase Pressure

jonnycycles · Post by **jonnycycles** » 27 Oct 2016, 18:21

Car: 2000 V70 XC
Mileage: 125000 mi
Problem: Excessive Crankcase Pressure

Symptoms: I initially noticed some oil leaking from the filler cap a couple of weeks ago, and then later a small oil leak under the car that appeared to be coming from the oil return port of the oil separator in the PCV system. Before I had a chance to investigate further I opened the hood a couple days a go and found the dipstick pushed out and a bit of oil sprayed around the engine compartment from the dipstick hole.

Only one OBD code, which I think is unrelated: P0422 Main Catalyst Efficiency Below Threshold. This code has been present since I've had the car (3 years/20,000 miles). I've replaced all vacuum lines and inspected for any vacuum leaks and exhaust leaks. The code will go away for a day or so after some spirited driving. I think it does indeed need a new catalytic converter.

My initial though was of course that the PCV system needs to be cleaned/replaced. I was dismayed as I did this 20,000 miles/3 years ago. When I did it then I found nothing clogged or damaged, but replaced the whole system anyway with all OEM parts. I took the entire PCV system apart again yesterday and found everything to be very clean: ports back to the engine are almost spotless and I can easily blow air though them, PTC nipple also spotless, all hoses/elbows in good condition, all clamps were tight. Some oil was indeed leaking from the connection between the oil separator and then engine block.

Anything else I may have missed with the PCV system that I should check before putting it all back together?

I found a light coating of oil in the intake manifold which I don't remember seeing last time I had it apart to do the PCV system. I also took the lower inter-cooler hose off to inspect: appeared normal there with a light coating of oil, but nothing poured out and it does not look like any more than usual was coming out the small vent hole in the bottom of the intercooler.

Any ideas on what can be causing this pressure?

My thoughts are to check compression once I have everything back together. Could excessive blow by be causing this? I've noticed no smoke when starting or driving, but was down about a quart of oil over the last 6000 miles.

Post by **scot850** » 27 Oct 2016, 20:18

When you did the work the last time around on the PCV did you use Volvo or aftermarket parts? I had an aftermarket elbow (the short 'J' shaped one from the side of the pcv box) split after only 700km! So if you used aftermarket parts and they lasted 3 years you are on a bonus!

Have you replaced the oil filler seal recently? Depending on mileage I recommend doing this annually if you do a lot of mileage or every 2 years max. That rubber ring has to work hard to maintain the seal at high temps and looses it's elasticity quickly. That will leak oil even without significant oil pressure.

Finally, carry out the rubber glove test on the oil filler and see if you get suck or blow!

Did you clean the PTC nipple in the turbo intake pipe when you did the PCV system?

Neil.

jonnycycles · Post by **jonnycycles** » 28 Oct 2016, 10:15

scot850 wrote:When you did the work the last time around on the PCV did you use Volvo or aftermarket parts? I had an aftermarket elbow (the short 'J' shaped one from the side of the pcv box) split after only 700km! So if you used aftermarket parts and they lasted 3 years you are on a bonus!

Replaced with genuine Volvo parts from FCP. All appear to still be in great shape.

scot850 wrote:Have you replaced the oil filler seal recently? Depending on mileage I recommend doing this annually if you do a lot of mileage or every 2 years max. That rubber ring has to work hard to maintain the seal at high temps and looses it's elasticity quickly. That will leak oil even without significant oil pressure.

Replaced 3 years ago, so it may be due.

scot850 wrote:Finally, carry out the rubber glove test on the oil filler and see if you get suck or blow!

Will do when its all back together. When I noticed the oil leaking I verified vacuum at idle at the filler cap.

scot850 wrote:Did you clean the PTC nipple in the turbo intake pipe when you did the PCV system?

Cleaned the first time around. Not needed this time as its still perfectly clean.

I'm a little baffled as to why the dipstick pushed out if the PCV system checks out as clean and intact.

Post by **scot850** » 28 Oct 2016, 15:04

Have you replaced seal rigs on the dipstick? I had he dipstick lift out until I replaced the 'O' rings. They may not be shown as available, but the later ones from the 2000- P2 is the same part.

Neil.

Post by **sleddriver** » 29 Oct 2016, 10:42

Odd indeed as you mentioned you verified vacuum @ idle upon noticing the oil leaks. Could be oil-dipstick o-rings. Valve stem seals? Might be getting waaay ahead of myself though.

I would verify that a good vacuum is actually being applied to the PCV system, as this is critical to its function. I drove around with a borrowed vacuum/boost gauge (FP gauge?) duct-taped to the windshield for several days when troubleshooting my turbo wastegate setting. If I recall, the sled motor was pulling about 18" of vacuum at idle. You may want to try this yourself if you're satisfied all ports are open, hoses are intact and not leaking/broken and nothing obvious is amiss.

jonnycycles · Post by **jonnycycles** » 11 Nov 2016, 19:50

Thanks for the suggestions.

I finally have everything back together. I put a rubber glove over the dipstick tube and I do indeed get vacuum at idle. If I gun the engine in neutral the glove starts to inflate but immediately deflates. If I give it a lot of gas in drive with the brake on I can get the glove to inflate more and take shape, which of course isn't that much pressure. Is some amount of pressure normal? How much pressure is too much?