Don't forget to check your PCV valve! Mine puked its guts out.

[MetroMPG]

One of the problems with an 18 year-old 3-cylinder car with 215k kms on it is it's sometimes hard to tell if it's idling poorly or if "nah, that's normal!"

But the Firefly's winter stunt double started idling low and randomly stalling last week.

OK, that's not normal!

When I opened the air cleaner, I could tell there was an EGR problem. It looked like a bit of oily goop had been dripping from the vent outlet onto the throttle body.

Carb cleaner to the rescue!

I gave the whole TB a once-over spray, then for some reason squirted a liberal amount INTO the PCV passage (illustrated by the green arrow, below) as well. Upon starting & revving up the engine, I heard a bit of a "pop!", saw a puff of something, and this is what greeted me on my return to the engine bay:



The PCV puked its guts out! GOOP! Lookaddit!

Moral of the story: don't neglect inspecting your PCV system. Mine was effectivey plugged up. The valve was also mostly stuck (open, I think) as well. Though I was able to clean it out with carb cleaner.

For some reason, I have never made checking the PCV valve part of my routine maintenance. Oops!

Always learning.

[Xist]

My Accord burns oil (and kills cats) and Shouty Kilmer said that if it is not a bad PCV valve, you need to rebuild the engine. I posted a twenty-second video of my beard replacing my PCV valve on Facebook wondered why anyone would pay a mechanic to replace that. All that I needed were pliers. Had I not spent five seconds fumbling it would have been a nice fifteen-second repair.

[A friend commented it looked like my beard did all of the work]

Sadly, that did not seem to improve the oil consumption measurably.

What are the standard things you replace on each of your winter beaters?

[Frank Lee]

Originally Posted by Xist

What are the standard things you replace on each of your winter beaters?

Suspension mounts. :/

[MetroMPG]

Shouty Kilmer. That guy!

I figured replacing PCV valves on a schedule was just a plot by Big PCV Valve!

Apparently as long as you can hear the check valve moving around freely when you shake it, it's good. (Or so said some page on the intarnet.) Before: no rattle. Post-multiple-carb-cleaner-sprays: free rattle. So I put it back in. I also cleaned all the plumbing & passages.

I should check to see if any more stuff barfed out of it since last weekend.

[ThermionicScott]

I checked mine last year, and was only inspired to bother since it was on that list of common mechanical problems that can rob MPG. It rattled fine when I got it disconnected from everything else, so I didn't gain anything, but it was a fun couple of minutes playing with cars.

[ksa8907]

Some newer cars use an orifice instead of valve. If you can retrofit, you might avoid having to inspect/clean the "valve".

[Frank Lee]

Back in the day I did all the rec'd maintenance By The Book- plugs, wires, PCV, filters, everything. It finally dawned on me the PCV is just a spring-loaded check valve that doesn't wear out; it just might get gooped up on occasion. Clean it with spray cleaner or toss it in the parts washer, blow it out, done. Now I don't replace perfectly good parts. I look at 'em and replace only if conditions warrant it.

Metro, you threw me off a bit when you said it puked it's guts out. I thought somehow the little ball got purged but no, it was only goop.

[MetroMPG]

Correct: only goop came out. The check valve stopper was intact as confirmed by cleaning the part (as you do).

---

Here's a question: how would a malfunctioning PCV valve hurt fuel economy?

I suppose if it's stuck open, it'd be continuously feeding some amount of oxygen-depleted blow-by gasses to the intake. That in itself should be slightly good for fuel ecnomy (like EGR) assuming it's a modern car with a properly functioning oxygen sensor: diluted intake = reduced power potential of the engine = wider throttle opening & reducing pumping losses.

But what if it's stuck closed? It'd increase crankcase pressure and possibly cause oil leaks (so I read).

[MetroMPG]

Originally Posted by Xist

wondered why anyone would pay a mechanic to replace that. All that I needed were pliers. Had I not spent five seconds fumbling it would have been a nice fifteen-second repair.

Yeah, I've had cars where this is basically a no-tools job as well.

The Metro required 2 screws to be removed to pull the valve, and of course they were seized, having probably never been removed in 18 years. So that required an additional tool. Also, it's buried beneath the air cleaner housing -- I had to remove that too.

Still, only a 10-15 minute job, not counting the cleaning process.