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PCV Catch Can & Intake Cleaning Interval

new 1/3/04, updated 6/13/2004,07/06/2004/03/12/2006

We know we must flush out PS every 25-30k and Fud never mentioned it. 

When FPS welded my cams at 70k nobody knew much about cleaning up the intakes, When Kirk cleaned my butterflies at 81k the SHO ran a whole lot better. 

So the question is how often should V8SHO recommend owners clean their butterflies to prevent IMRC failure? 

I am thinking every 36k or 48k? Maybe every 40k since PM intervals is every 5k? I would like a consensus so we can put it on FAQ 



That sounds very reasonable.


I welded my lowest mileage car at 49K and they definitely needed cleaning. The secondary valves were also contaminated and needed cleaning. See my earlier post on "sticky valves". The B&G flush seems to work (from that post) and I was offered it for $70 at local Big-O tires. This route I would say 30K, manually at 50K.


Eric Lehmann says every 50k

Regards Eric

I agree with the 50k as scheduled maintenance.

I would also say that if you have the time and you can do this for yourself at least once a year.. Eliminating the Vapors from the PCV and the “fresh air in” in the first place would cut this WAY down.

Kirk J Doucette

My intake really needed cleaning when I opened it up at 50k - I'd say no more than 50k.

Brad Bender

Paul says modify the PCV system, use Amsoil and every 60k along with the plugs.

Paul Nimz

Mine had 53k when the butterflies stuck. Stupid stealer replaced the lower manifold assy. ($1173) rather than clean it. I was surprised that the ESP was willing to pay for it!

Take care, -- Rob Parker

Here's a pic of my first install of my con can and of the PCV hose  re-routing. >

Paul Nimz

CatchCan 3rd install.jpg (39088 bytes) PCV hose routing 2 w highlight.jpg (52109 bytes)

Do you got a materials list and instructions? It's hard to see from just the pics.


did a google came up with these ( pardon the mopar ) www.neonrick.com/oilair_howto.html & http://srt4.thebatanesislands.com/mysrt4/gal_20bux_catch_can_060203.html 

Rick Bergstrom

I suppose you really want to mount the container in an air flow to make sure its cooler than the PCV vapors, probably doesn't need to be fully exposed just cooler, to enhance the condensing action.

I like the PVC idea, about $6 to make? If I have time I'll check it out tomorrow.


from my readings , Paul Nimz has the catch can mounted low in front drivers fender well , others have it mounted under valence in front of the radiator- where your auxiliary trans cooler should be .although i am not too certain if the "cooler" place is necessary , the catch can will work either way . 

Rick Bergstrom

Just for clarification, I consider mine a condensation can. The blowby gasses by definition and in fact are not liquid or solid. The hot gasses will condense out in the aluminum tube I use and where it is located.

Paul Nimz

so in this case , you are saying that the metal canister would work better as the aluminum (compared to a plastic ) would cool the gases more quickly ? 

Rick Bergstrom


Paul Nimz

I took a look at the local ACE Hardware and if you can live with a one inch diameter can it can be constructed without the need to drill and tap from off-the-shelf components. You do need to glue the PVC pieces together with cement. Here's a list of parts:

slip 1" x 1/2"F(emale) reducing elbow threaded on the 1/2" 
1" pipe 1 ft. (what ever length you want) 
slip1"x 1" x 1/2"F tee threaded on the 1/2" 
slip1" to 1/2"F reducer threaded at the1/2" 
1/2"M(ale) to 1/4"F threaded reducer (brass) 
1/4"M drain valve (brass) 
1/2"M threaded to 3/8" barb (2) (plastic or brass)

Cut the 1" pipe to the length you want the can to be when the elbow and tee are added and assembly the pieces in the order above gluing or screwing as appropriate. And hose to mount where you choose.

If anyone wants the SKUs I can get them.


Be sure to keep track of the total cost including hose, clamps and other miscellaneous items. FWIW 1" PVC is not the material you want to be using. And there is no internal baffle.

Paul Nimz

Yes. I was wondering about something along those lines. Some thing at the outlet. I see in those older cans used BBs, I assume high surface area - what about steel wool. And, I agree metal would be preferable, but as a quick try out the PVC is cheap. Each piece is between $0.90 and $1.50. If you have the correct tap already the original design is even cheaper.


I don't see the purpose of the steel wool or bbs except as a filter. What you want is the largest external surface area and some way to force the gas to contact that surface area internally.

As the plastic MAF is better at rejecting heat so would the PVC tubing.

FWIW with my first tube I used a very thin 3" PVC tube (~sch 160). In about five miles I had to disconnect it as it collapsed from the vacuum and heat. It was locate at the bottom of the radiator.

Paul Nimz

I also took a look at the air line filter, at ACE it was $40. Tried the local PepBoys they said they didn't carry them.


I used a metal in line fuel filter once. Again this is a gas that we are dealing with and therefore there is nothing to filter.

Paul Nimz

As a general rule, it's not a good idea to use PVC in hot environments. I don't know the specifics, but at some point it gives off chlorine gas.

Paul, I like your suggestion of aluminum conduit.

Brad Bender

My second (and the one that is pictured) is made of thin wall aluminum tubing. This is good but offers no way to thread it. I used JB weld and lock nuts. The JB weld failed and now the drain valve leaks around the brass threads. Hence the self draining technique. :)

Paul Nimz

It's really a moisture separator/air filter. The filter is removed and the bowl acts as the catch can.

Lowes have a unit for $25 that's sturdy, with a removable bowl and has a built in drain tap on the bottom.

Paul, at what rate does the oil collect? The amount collecting in the surge tank is not the best thing to judge by, as it has the full air flow , EGR gases passing through it and suffers from heat soak, but it's all I have to go on.


I would collect about a 100 ml a week. This with maybe 200 miles and in the summer, and with a closed PCV system. An open one will collect about double that amount.

Paul Nimz

So how do I make one??? The right way. With a parts list and specific instructions for someone like me who's not too great at rigging stuff like this up.


Details pending - Buford


Finally got round to making one just to try; out of 1 1/4"PVC fittings. I know a metal one would work better. I'll report on how well it works. How much gunk I get out. Then I might build a hi-tech aluminum one.


You will be surprised at "how much gunk " you will separate out of the return lines ! Not that it matters to you Arizona folks - don't let it freeze in the winter - it makes a mess ;) Rick B

Do you put anything inside this can or is it just empty?

Steel wool to break up the airflow. jj

Those are 3/8" barbs I'd go down one size and pipe to match. If you want to try. jj




FWIW, using a PVC male nipple with a female brass fitting will help prevent thread splits – PVC has better compressive strength….just don’t over tighten regardless…especially with PVC tapered (NPT) threads. Also, PVC is only rated to 140 deg. F max (CPVC around 180) & is not rated for any positive air pressure…fragmentation gets nasty under positive (compressed) air or gas pressure should it fail…vacuum service is okay as a FYI. If PVC is exposed to any oils or solvents, stress fractures will probably occur (PVC is good for acid / chemical resistance with exceptions). I don’t see any solvent cement on the sockets unless you used a clear 1-step.

Bill H.

Technical Field Rep. for a thermoplastic fitting & valve manufacturer



Here are pictures of my Con Can installed. You can also see where I use silicone on the aluminum bushings to keep any vibration down and to provide dissimilar metal corrosion protection. You can also see the bottom of the windshield washer tank.

In the back of the fender is the vacuum tank.


Paul Nimz



Here's the catch after a couple of weeks you can see the gunk in the line. None the worse for wear. Although it does need the correct tubing.


I was thinking that this might be a good start at a PVC catch can. 

I started looking for fuel filters to use for this, after I remembered seeing some really big fuel filters, whenever I walk by that section in a parts store.

Haven't found any dimensions, though. 

Would probably need to be modded to add a baffle.

The drain is nice, and comes with mounting hardware...

Best Regards,
(Not that) Doug

The PCV gunk that you are trying to catch are gasses. They need to be condensed and then trapped. This filter may do this but to remove the gunk you will need to replace the filter. If you do any driving this would be at least once a week.

Most of the PCV gas is water and the rest is light oil based. There are no solids or liquids that are in the PCV gasses until you trap them though condensation. Most filters will just allow this to flow through.

What you need is a catch can like Summit racing has with an inlet, outlet and drain. Mine has an automatic drain and will puke out about 50 ml per 50-100 mile trip. The more moisture in the air the more discharge. http://store.summitracing.com/ search for catch can.

But a filter is not what you want.


You know after looking at that again and going to PermaCool's website that thing may just work. It would have to be located out of the engine compartment though.


___________________________________________________________________________Just guessing from the fitting sizes, I am thinking that the filters are probably about 2.5 inches in diamter and about 4.X inches tall.

There were some other filter kits I looked at, but they were a little scarce on size info as well. I did like the drain on this one.

Best Regards,
(Not that) Doug


What you could do is make a metal or plastic sleeve for the filter that covers all but the top inch of the filter. That way the gasses would be forced to contact the metal sides of the housing enhancing condensation and any liquid would be kept out. Still have to drain it every day though. Wonder what the thread is for the drain?


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