What does your Positive Crankcase Ventilation (PCV) valve actually do?
Alright, so you’ve rocked up to the workshop, and you’re asking, “What’s this PCV valve I keep hearing about?” Good question. Basically, the Positive Crankcase Ventilation (PCV) valve is one of those little things in your engine that does a surprising amount of work, especially for drivers here in Hamilton and the surrounding towns, like Te Awamutu, Cambridge, or Morrinsville.
Every time you’re sitting in Dinsdale traffic or pulling onto Wairere Drive, your engine’s making a bunch of tiny explosions to get you moving. This makes a bit of a mess inside with nasty gases that can sneak into the crankcase (that’s the bit that covers your crankshaft). Leave those gases in there, and you’re in for all sorts of headaches—think gunky oil, extra wear, or blown seals.
The PCV system’s job? Take those gases, pull them out, run them through the PCV valve, and send them back into the engine for another burn. Nothing wasted, cleaner oil, a happier engine. In real world driving—like inching along Heaphy Terrace in winter fog or belting across Avalon Drive when it’s 30 degrees out—it keeps things running smooth and helps with fuel economy too. Handy on the wallet, with Auckland petrol prices!
Why do PCV valves fail?
Like anything, PCV valves don’t last forever. We see all sorts here: maybe you’re driving a Toyota Aqua, Subaru Legacy, or even something a bit different, like a SsangYong Korando or a Peugeot 308 from out Paeroa way. PCV valves can get stuck open (letting in too much air), stuck shut (blocking it off completely), or the seals go and oil leaks start. Heavy stop-go stuff round Chartwell or all those speed bumps out in Rototuna can accelerate wear. Hot summers or those damp Hamilton mornings don’t help either.
Signs your PCV valve might be on the blink
These are things we see every week, regardless if you drive a Mazda Demio or a VW Passat. Here’s what you might notice:
- Oil leaks showing up under the car
- Excessive engine pressure and maybe a burning oil smell under the bonnet
- Bit of extra smoke (especially on cold starts after a night parked in Nawton)
- Tappety sounds or harsh idling when you’re stuck at the lights on Grey Street
- That annoying check engine light coming up on the dash
- Struggling with rough idle or you’re experiencing misfires—especially common in Honda Fits
- Engine power drops, or you suddenly feel like you’re missing a bit of grunt going up the hills into Tamahere
- Sometimes you’ll get a lean air/fuel mix which can trip codes and mess with your emissions
If you’re wondering about the nuts and bolts behind the PCV system, there’s a good, simple breakdown here: Learn more about the PCV valve >
PCV valve replacement and repairs – Hamilton
When a PCV valve goes, it’s one of those things you want to sort quick to avoid other engine dramas. If you’re from Gordonton, Raglan, or even Ngaruawahia and noticed any of those symptoms, or just want a check while you’re in for a car service or WOF Hamilton, we’ve got you sorted.
Our techs see this on all sorts—lots of Nissans, Mitsis, Audis, even the odd Hino van doing the rounds for a tradie in Ruakura. We’ll get in there, diagnose the issue, and fit a genuine part that’ll go the distance through all of NZ’s wild seasons.
Don’t wait till the engine’s running rough or the oil light’s on; swing by Grimmer Motors and let us check it over. Quick, affordable, and keeps you safe and sound on the road—no stress whether you’re running kids to netball in Frankton or braving the Commons Ave potholes.