Testing PCV system

[JOD]

Greetings,

I just picked up a '06 Focus Wagon, 2.0 Duratec/manual tranny, 89K on it--private party. Oil changes every 5K, one wheel bearing replaced, front rotors and pads--no other maintenance. The car was garage-kept, looks great, drives great. So, far I've changed all of the fluids (coolant/PS/brake & clutch/MTF), changed the plugs and cleaned the engine.

Funny aside, I asked the owner (self-professed car guy who did his oil changes and the brakes) if the transmission fluid had been changed. He looked at me funny and told me it was a manual, so there was no fluid... Everything else checked out, so I just let it go and told him I thought there was some fluid in there somewhere... Other aside: Ford's million dollar synthetic MTF looks great @89K, and I noticed zero difference in shifting after changing it. I'm very impressed w/the fluid, and felt less bad about the $13.XX a quart price after changing it!

So, last maintenance item before I begin dismantling the interior for the big sound deadening project: the PCV valve and hose. I know these are prone to cracking (the hose) on this engine. Is there any way to actually test this out, say with a mamometer or something? Before anyone chimes in w/"just change it", please understand it's not that simple--the IM has to come off. I'd really prefer to wait until the spring, mostly because I just changed the oil and after pulling the IM my OCD would require me to change it again. Plus, if it's intact I'd just as soon wait. I do have the parts on-hand already.

I've not experiencing any idle issues/error codes, or hissing noises, but if there's dirty air being sucked in there I'd like to get it changed. Anyone have any knowledge on how to actually test the system?

Thanks!

 

[dlundblad]

IIRC, a UOA can tell you whether or not you are getting excessive contaminants (dirt) into your oil. Maybe that is where you could start? Couldnt a bad PCV make your oil appear darker faster? Someone please chime in. Heck though, with that a UOA costs, you could buy MC oil/ filter at WM and be golden.

 

[jk_636]

Just replace the PCV valve and hose if applicable. Its just easier that way!

 

[raytseng]

just change it in spring then.

If it's a big hassle, even if the valve is a bit worn; it's not going to make a huge difference changing it now or later. It's already been in there for 89k miles, 5more won't make a difference

 

[1 FMF]

get a vacuum/pressure gauge, such as for fuel pressure, and rig it up to measure the crankcase. don't know where you can measure from, sometimes the easiest is removing dipstick tube and sliding hose over it with a hose clamp. you're only measuring +/- 5 psi at most so it just needs enough to seal.
ideally so should see 2 psi at most of vacuum and not more than 1 psi of pressure in the crankcase. easy enough to measure parked at idle but you really want to know under load on the highway at low and high rpms, so you would have to get creative with the hose somehow reaching inside the car.

 

[JOD]

Originally Posted By: 1 FMF
get a vacuum/pressure gauge, such as for fuel pressure, and rig it up to measure the crankcase. don't know where you can measure from, sometimes the easiest is removing dipstick tube and sliding hose over it with a hose clamp. you're only measuring +/- 5 psi at most so it just needs enough to seal.
ideally so should see 2 psi at most of vacuum and not more than 1 psi of pressure in the crankcase. easy enough to measure parked at idle but you really want to know under load on the highway at low and high rpms, so you would have to get creative with the hose somehow reaching inside the car.



Awesome-thanks! So, if the hose is cracked, how do you think that will affect the pressure and vacuum readings?

 

[JOD]

Originally Posted By: raytseng
just change it in spring then.

If it's a big hassle, even if the valve is a bit worn; it's not going to make a huge difference changing it now or later. It's already been in there for 89k miles, 5more won't make a difference


Yep, fair enough. It's not consuming any oil and the oil was very clean at 5K, so it's not like the rings are being sandblasted... I should mention that I'm not at all concerned about the PCV valve itself--spotless engine and no oil consumption. It's more the (potentially) cracked PCV hose. You're right though, waiting until spring is probably fine...

 

[babbittd]

I know of two simple methods with which to test a PCV valve.

With the engine idling, unscrew the oil cap and put a stiff piece of paper or a rag over the hole. You're looking for evidence of suction.

With the engine idling, pinch or clamp the PCV hose and watch for a drop in RPM.

 

[sleddriver]

Since it's a new-to-you, what about a smoke test? Easy way to track down any rotting rubber, cracked plastic hidden away from a clear view.

Keep us posted about your sound dampening project. I wrote up my tailgate project earlier. Really quieted it down. The rear over the wheel-wells definitely needs work, lots of noise from there.

Congrats on your find!

+1 on leave it till Spring.

 

[hsd]

Another variation on the "suction" test is to disconnect the pcv fresh air hose usually connected to the air intake filter housing or tube (not sure on your 06 Focus) and see if there is a slight vacuum there with the engine idling. It should hold a piece of paper against the end of the hose.

 

[artificialist]

If you spray carb cleaner all across the PCV hose, a change in RPM will indicate a leak.

I understand that replacing that hose can be a pain, unfortunately, I am used to having those hoses fail on Ford engines earlier than most other engines.

 

[KitaCam]

While you're at it, OP, check ALL the hoses, and check anything rubber...belts, bushings and engine mounts...for aging.

 

[SHOZ]

If the hose is leaking and cracked you would be getting an O2 code of some sort.

I use to run the PCV system sealed at the valve cover makeup air hose with my Ford Taurus SHO V8. I would usually see around 5" of vacuum on the crankcase at idle or part throttle.

 

[babbittd]

Originally Posted By: SHOZ
If the hose is leaking and cracked you would be getting an O2 code of some sort.



Yes.

And the oil cap test that I previously mentioned, is probably the sort of thing that unless one has a lot of experience with one engine, they might not recognize that which is cause for concern with this test alone. The elbow in my Taurus appeared to be restricted, it had the "sucked in" appearance (and was the most likely cause of an oil leak that has stopped since the elbow was replaced), but there was no effect on the fuel trims and oil cap / flutter test told me nothing.

 

[JOD]

OK, thanks for all of the responses! I did the following:

-visual test (high-powered light and a small mirror from the top and bottom of the engine), I could see about 60% of the hose, didn't seen any cracks

-sprayed brake cleaner around the hose while the engine was running--no change in idle.

No change in idle. So, I think I'll find something else to worry about for now... Doing some more looking, I think I'll replace the t-stat and a couple of hoses when I do the PCV stuff, since access will be a lot better with the IM out of the way.

Besides this, all of the other maintenance is all caught up. Working on the car is a bit of a mixed bag. Access is good on some stuff, quite tight on other stuff. Things are pretty tight in the engine bay, which is now quite a bit cleaner than when I got it:

Yes, the previous owner wrote the oil capacity on the valve cover--just in case he forgot!