2004 CHEVROLET SILVERADO 1500 4.8L V8 : Emission : Vapor Canister Purge Valve

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by skjl47, Nov 29, 2012.

  1. skjl47

    skjl47 New Member

    Hello; I am new to the forum. I joined after some searching on a check engine code; P0442. I have discovered this is a small leak in the emissions setup. I replaced the gas cap with no joy. I am considering the replacement of the vapor canister purge valve. I have the replacement part but it is a bit different from the factory part in that it does not have a long section of hose attached. The factory hose appears to be shrunk over the fitting on the pruge valve.
    I have been reading about this replacement and there seem to be some indication that the part should be moved to a different location. Even if I do not change the location, it appears that I will have to cut the existing hose and join the new canister to the hose with a 5/8in heater hose.

    I will start with one question with regard to replacing the part and leaving it in the factory location. It seems possible to me that the plastic hose might collapse when squeezed by a hose clamp when attaching a section of rubber hose. Is this an potential issue? If it is, what can be used to reinforce the plastic factory hose from the inside to avoid the collapse?

    I have not decided to relocate the part as yet, but welcome any comments as to that procedure.
  2. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    I don't think that a po442 relates to the valve. it is usually the gas cap code. Did you buy an OEM gas cap from GM? Sometimes the after market caps do not seal correctly. Did you clean up with some sand paper where the gas cap seats on the filler neck? I have also seen a poor connection where the hose from the tank to the filler neck has a bad, corroded connection. You can also pull the filler neck hose, clean up the tank where the hose slides on and the neck where the hoses slides on. Unfortunately I have also seen the seal on the top of the tank where the fuel pump/sending unit mounts go bad and cause this code. Any way now to answer your question, you could use a straight barbed connecter. Here is a picture of one.http://stores.ebay.com/Clear-Braide...ght-Hose-Connectors-/_i.html?_fsub=1484495010 Not the size you need, but it will give you an idea of what I would us. You can find them in brass, plastic, or stainless. Your local auto parts, hardware, or homedepot type store should have them. Some places have them with different sizes on each end. Hopefully replacing the valve fixes it. I have seen pinholes in the line running up the to motor cause the same code. IF that is the case then you get to make your own smoke machine to try and find the leak. (easy to do)
    Last edited: Nov 29, 2012
  3. skjl47

    skjl47 New Member

    Hello; Thanks for the reply. I have read a bit about the smoke machine and may get to such a device. One additional question. Would anyone suggest the use of anything to help make a good seal, such as silicone? I have a tube of sensor safe silicone (red in color) handy.

    - - - Updated - - -

    Hello; I had the factory gas cap on hand in a bag as I had replaced it with a locking gas cap when the truck was new. I simply put the factory cap back into use but did not attempt to clean the surfaces. I will do so and see if that helps.
    I did make a visual inspection of the hoses and fittings and did not see anything obivious. Thanks for the suggestion.
  4. j cat

    j cat Epic Member 5+ Years 1000 Posts

    the p0442 code is created when the computer commands the canister purge valve and canister vent valve to on for a period of time to create a vacuum in the fuel tank. when the fuel tank vacuum drops to quickly you get this code.

    most times a bad cap. with an old vehicle it could be the fuel filler pipe at the gas cap. I have found this to rust out at the unpainted welds on this pipe bracket. This can be patched with 5 min metal mender, then use a good mineral based rust proofing to prevent future holes.

    The other area is the valves are cruded up with charcoal gas goo from overfilling the fuel tank and then parking the vehicle before excess fuel can be burned off , or filling up then parking the vehicle in a heated garage in winter.

    remove the larger vent line and inspect for contamination. if its got the goo in it you will need to replace that line and get a new charcoal canister and possibly the canister vent valve.

    these connections should come off quick disconnect. if not they do have splices made for this if cutting is required as well as quick disconnect fittings . having the dissconnect tool helps make this easier. could also be a rusted out metal vent line to engine. that would be a bad day for me.
  5. skjl47

    skjl47 New Member

    Hello; I did a search on a smoke machine both on this forum and a web search. The forum search had little joy as any post that mentioned smoke came up. The web search resulted in some information. Can anyone post a link to site about making a DIY smoke machine that they like?

    - - - Updated - - -

    This is a possibility as I live about seven miles from the gas station where I often fill up. I also often have trips of only 15 miles or so. The truck is an 04 with 35,000 miles. I make a point to drive it at least once a week but often only 15 miles or so.

    Can anyone give me a bit more information about the location of the larger vent line and the disconnect tool?
  6. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    I don't have a link, but can tell you a cheap way to make one. Get a 2 liter soda bottle. Buy something like this: http://www.westmarine.com/webapp/wc...gclid=CLeIgPW4_rMCFQVgMgod7G0Arg#.ULy29deICSo

    I just take a cigarette into home depot with me so I can get a barb that will fit a cigarette snugly.
    Drill a hole the the cap in the soda bottle and a hole in the bottle itself. (the correct size that the hose barb fits tightly) Insert the hose barb into the hole that you made in the cap. The barb should stick thru the hole while the threaded end goes toward the inside of the bottle, (into the cap). Light a cigarette, stick the filter into the hose barb threaded end. Now screw the cap on the bottle. The burning cigarette will now be inside the bottle. Now just put your finger over the hole that you drilled in the bottle and give the bottle a squeeze. You should now be shooting smoke out of the tip if the barb. Uncover the hole in the bottle and let it reinflate. Put your finger over the hole again and squeeze. You can hook the bottle to a hose using the barb. If you want to put a t on the ene of the hose then you can just hook it inline where you want your smoke. I have put the blow gun from my compressor into the hole in the bottle also. Then you just need to keep putting fresh cigarettes in
    Last edited: Dec 3, 2012
  7. skjl47

    skjl47 New Member

    Thanks; That is a new idea.
  8. j cat

    j cat Epic Member 5+ Years 1000 Posts

    I got a cheap plastic set of these quick disconnect tools/set at carquest.

    they are for all the sizes and small so you can get into a closed in area to insert the tool into the fitting then rotate slightly and pull. alittle wd-40 helps and if you have some air pressure blow out the grit / dirt which will interfere with the removal. cost was 10.oo...

    this is the tool set http://www.ebay.com/itm/A-C-and-Fue..._Automotive_Tools&hash=item3a7c218e47&vxp=mtr
  9. skjl47

    skjl47 New Member

    Hello; Thanks for the reply. I have a set of that type pictured in your link. I also have compressed air.

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