TOPIC: PCV System issues

Since The Powers That Be have seen fit to give us so many different configurations on the PCV systems-some are even built into the intake manifolds-I figured we needed to have a place to discuss these most critical systems.

If you have an issue in addressing the PCV, then post your questions and your solutions right here for the benefit of all.

For a good explanation of the PCV System (Positive Crankcase Ventilation) see this Wikipedia article: Crankcase ventilation system - Wikipedia

In the later models of Dodge vehicles, the PCV Valve is located to the left of the Throttle Body, and is covered by a plug. This is for certain in the 2004 Series 5.7L engines, and may be why you can't locate yours.

The best way I have found to plug this terrible drain on our fuel efficiency is to remove the PCV Valve from its nesting place, and to simply fill it with RTV. Of course, a good cleaning is advised to increase the chance of a good seal.

So, this is the process:
1) Rotate the plug (or PCV cap) Counter-clockwise. It will probably be very tight, so grip it well. (I've had to use channel-locks on a couple.)
2) Using a pair of needle-nose pliers, reach into the hole and work the PCV Valve out of the housing. It will be tight, as it has two "O" rings keeping it sealed against leaks.
3) Once it's out, invert the valve and spray it thoroughly with Carb spray. Shake it with the solvent inside until you feel it's fairly clean.
4) Squirt your RTV into the hole at the bottom of the PCV. This will be a small hole with a little disk visible that closes off the system when there is no vacuum available.
5) Let the PCV set until the RTV hardens (read the instructions for set time) and then reinstall it into the intake manifold.

This procedure will work, even on the electronically monitored PCV systems. So, if you run across a PCV system that has wires connecting it to the computer, address it in this manner, rather than by simply plugging the vacuum line at the intake manifold.

I hope this helps!

Ron

In some cases when you want to reroute the
PCV line to the air intake, here is a handy
draft tube that makes exhausting the crankcase
blow-by gasses more efficient & effective.

This device would also contribute to minimizing or eliminating
the positive-pressure in the crankcase, this will help the
oil stay cleaner longer.
This device is also used for the hydrogen feed-line for HHO systems.

So Ron, you are saying that I can fill my PCV valve with RTV and the vehicle computer won't even know. Right?

Hi Inspector Gadget,
The RTV suggestion is for 2004 5.7 Hemis specifically. As a rule you don't fill in the PCV valve. The goal is to plug off the vacuum port on the intake where the PCV line connects (which is a huge vacuum leak), never the connection to the valve cover. The vehicle's computer does not know if the PCV valve is plugged or not.

On another note, welcome to the forums and what is your name and where are you from?

Nick from New York state

Hi Nick,
Thanks for the clarification. Ron said ...IF you run across a PCV system that has wires connecting it to the computer, address it in this manner...
so I wanted to double check.

I am Dan Grieve from South Central Missouri.
I posted my first MOD earlier today, the 08 Highlander.

Hey Dan!

The Hemis are the ones with the PCV under a plug in the intake manifold. These are the ones to plug in this manner, although I do NOT recommend RTV. This is simply too flexible to use in such a large opening. Use JB-Kwik. It dries hard and creates a plug. Hence, the advice to "undercut" the opening with a drill bit.

This diagram shows what I mean, with apologies for the lack of artistic demonstration...

PCV Valve Plug diagram.png

By sitting it upright on plastic, the epoxy will settle into the opening, guaranteeing a plug that will not come out and the plastic peels away cery easily once it sets up.

Do this for the electronic PCV's and for those that are built-in to the intake (as in the Hemi's) for best results.

Ron

Hello, all

Harry here from Sedona Arizona.

I've got a 2005 Dodge Magnum 5.7 Hemi. This thread sets this engine apart by saying the PCV valve should be "plugged" at the PCV valve, not at the intake like others. Why is this? GadgetMan did my Groove, and he just capped the port at the intake.

With that in mind, however, I've had negative MPG results from the groove itself - I've lost about 1 mpg (avg) since grooving, and gained an annoying whistle.

Just last week I uncapped the PCV valve and reconnected. I've regained the 1 mpg, and possibly a little more (the whistle is still there). I thought the PCV valve was suppoed to be a drain, not an aid, in fuel economy?

Hi Harry,

I don't know the specific engine yr/model that you have so I will direct my response to the function aspect.

We typically move the PCV line from the manifold side to the plenum (air in) side of the throttle body as this increases the manifold vacuum and still processes the engine gases that come through the PCV valve. That increase in vacuum adds to the effect of the groove itself. In a case where the PCV itself is plugged, typically there is a secondary vent that is already on the plenum side, so the result is the same in that respect.

It is quite possible that there may be a vacuum leak that went undetected. Only way to really find out is hands-on, sometimes that increase in vacuum can bring to light a potential leak that otherwise would be ignored. My thought on your possibly getting added mpg, your PCV valve may be partially clogged giving you 'some' added vacuum but not enough to affect a potential leak at a higher vacuum. As I said, only a thought.

As far as the whistle, that is the groove itself, the air flowing over/through the groove has the same effect that you would get when blowing across a beer bottle.

We are pretty much in agreement that if you can hear that sound that the groove itself is correct.

You might be able to connect with Ron when he comes back through your area, he's currently up in Nebraska kicking off the 2012 Groove Tour.

Karl Fortner
Tacoma, Wa.

Thanks for the quick response.

As I stated in my original post, I've got a 2005 Dodge Magnum 5.7 Hemi.

Ron had mentioned that some grooves get the whistle - and that once you've got it, you're never getting rid of it. I wouldn't care so much if I had realized an MPG increase, but it's been 4 months now, and all of the tweaks Ron suggested have netted zero (0) improvements. I was going to post something on that in the main forum, not in this PVC thread.

Anyway, I hadn't actually meant my question as "why plug the PVC". I was actually interested in why the Hemi (plugging at the filter, rather than capping the port) required a different method. And, I guess, why Ron, seeing I had a Hemi when he did the groove, just capped it. And, with all the tweaking we've tried the last 4 months, never suggested anything like what was specified earlier in this thread.

As for the vacume leak, I definately cannot rule that out! Ron had suggested checking for that a couple months ago. The car does have 80k+ miles on it, so age alone could contribute to that being an issue. I tested for leaks using carb cleaner, with no obvious changes. I knew about the smoke test, but I don't have any access to that kind of device. Even if I replaced every hose in the engine (of which there are surprisingly few!), that still wouldn't cover possibilities like gaskets, seals, or o-rings. Not to split this thread, but I had intended on posting something on that in the main forum as well.

Thanks again!

I grooved a hemi 2005 a couple weeks ago and she was getting 11.5 before groove after groove and reset ecu she reported back 16.9 and climbing 4x4. dan gadgetman mo.

Hmm. Then something is either wrong with mine, or with hers.

I was getting roughly 19 combined and 21+ (highest 24.5) highway before the groove. After the groove and all the tweaks Ron & I've done trying to figure out why 0 results, the combined dropped to approximately 17 and highway rose to between 21 and 22.

If she was only getting 11, something had/has to be seriously wrong with hers somewhere. Even allowing for different climates, driving habits, fuel source, that shouldn't add up to an 8mpg difference! Unless, of course, she drives like a friend of mine - 0mph or 100+, never in between (fun, but expensive!). LOL

In my case, Ron had me test for vacuum leaks - I couldn't find any. He then had me reset the computer (disconnect battery for 12 hours), no significant difference.
I added the PCV back into the system (desperate for some change), and it seemed to tweak up some, but it's returning to "normal" again, so that blip was probably fuel, temp, etc; still net 0 results.

The only other item is that my Hemi has a CAI installed. I'm loath to spend the money (120) on reverting to the stock setup, but since the groove works on the airflow, ?? I don't care about CAI (car came with it), but I do about the $120!

I would kill for a 47% fuel economy increase. I did the groove specifically for fuel economy, not for performance. As it is, I'm at 0%.

Just out of curiousity, did she end up with a whistle, too? And, by "reset ECU", you mean disconnect battery with key on "ON" for 12 hours, correct?