I've been suspecting an issue with the PCV system in my Opel Astra H 2008 with a Z14XEP petrol engine. It blew both the oil pressure switch and (probably, have yet to investigate) the front crankcase seal in short succession.

I tried the old "balloon on the oil dipstick tube" trick, which seems to show significant positive pressure inside the crankcase, even at idle.

Video: https://drive.google.com/file/d/0B19XZxlznCy5WXdXMUhtaFNUNjQ/view?usp=sharing

The video was taken at idle. I think I can feel individual cilinder pulses in the balloon.

How do I fix this issue? I checked the rather large hose going from the valve cover to the T junction before the throttle body and it's not blocked.

Some additional information: the engine oil cap is always caked with a mayonnaise like substance. This is apparently rather common on these engines and not indicative of head gasket failure. The engine oil does not contain coolant.

Do I need to install a new valve cover?

Edit: I found some related material: here. It's not the exact engine (1.6L instead of 1.4L) but it's close. I checked the hose that connects to the intake manifold and that's definitely not blocked (lot's of vacuum).

  • 1
    If it were a pcv problem you'd have excessive vacuum in the crankcase. do a leak down test 1st.
    – Ben
    Jul 16, 2017 at 13:00
  • If the PCV system is plugged up, wouldn't blowby cause excess pressure inside the crankcase?
    – Ives
    Jul 16, 2017 at 13:05
  • It can but it's doubtful. This may be a dual breather system, I'm unfamiliar with the engine. Check for airflow on the breather hose(s). Check for sludging of the oil.
    – Ben
    Jul 16, 2017 at 15:52
  • I changed the oil literally the day before yesterday. The old oil looked fine. It's hard for me to perform a leakdown test: I don't own a leakdown tester and they seem relatively expensive. The engine has about 70 000 miles on it, so while not impossible it would be rather early imo for the engine to be worn out.
    – Ives
    Jul 16, 2017 at 16:00
  • By "check for airflow on the breather hose", do you mean disconnect the breather hose at the engine, pinch it off on the intake side (to prevent dust ingress) and test if air is leaving the engine block through the breather hose "nipple"?
    – Ives
    Jul 16, 2017 at 16:03

1 Answer 1


Sound to me like I would want to rule out a cylinder head gasket, or possibly a cylinder head.

You could have a leak from the coolant to the oil passage, which is causing coolant to mix with oil, giving you the baby poop look inside the cap.

Also, if you have a combustion to oil leakage that could cause the seal to go. The oil pressure switch doesn't make sense just yet, as it should handle rather high pressures, UNLESS your combustion is flowing into your oil at higher power levels.

What does your coolant overflow bottle look like? If it is contaminated, that is one more check mark towards a cylinder head pull.

You need to be really careful. If the gasket has gone, you may not be cooling and lubricating your cylinder head properly and it could have a catastrophic failure. Also your radiator and cabin heater could blow if they get overpressured and your radiator cap has insufficient capacity to vent combustion leakage.

I urge you to resolve this before you put more miles on the engine, and potentially do more serious damage.

Cost wise, look for 1. mixing of fluids, 2. contamination of coolant with exhaust byproducts, 3. compression test which can be done with a relatively low cost gauge.

  • I'll take that under advisement. You should know that the mayonaise has been on the filler cap ever since I first opened the cap maybe ten thousand miles ago. There's also many references on the internet noting that the mayo on the filler cap is caused by the plastic valve cover on the Z14XEP, which cools quicker than the head thereby causing condensation. Especially on short trips (which this one drives). And that on this engine it's not indicative of head gasket failure. As noted in the comments, the oil was also not contaminated. Coolant is not contaminated.
    – Ives
    Jul 16, 2017 at 20:29
  • If you are sure of the coolant and oil condition, then that is fine. To answer your question about changing the valve cover...I see no reason as to why. Is it leaking? Didn't think so. Going back to the PCV, typically they are rather inexpensive, and often replaced when on the suspicion list. How much is the one for yours? I hate to shotgun, but the shells are cheap when they are PCVs.
    – mongo
    Jul 16, 2017 at 21:54
  • Both questions have similar answers: as far as I can tell (going off of internet sources and the distinct lack of something PCV valve like) on this engine, the PCV valve is integrated into the plastic valve cover. It's supposedly a rubber membrane that is molded into the plastic inside of the valve cover.
    – Ives
    Jul 17, 2017 at 8:04
  • I found some related material: here. It's not the exact engine (1.6L instead of 1.4L) but it's close. I checked the hose that connects to the intake manifold and that's definitely not blocked (lot's of vacuum).
    – Ives
    Jul 22, 2017 at 19:45

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