98 v70 NA P0455 - my most loyal friend

[theWIFES_S70]

What about the carbon canister? Or the small lines that connect to the carbon canister? Have you thought about replacing those?

[98v70dad]

Everything up front except the carbon canister is new. That includes all those little hoses on the carbon canister. I'm told that the canisters almost never need to be replaced. I inspected it when I replaced all the hoses and it looked fine...no holes or cracks.

Yesterday I found a pinch in the plastic line that runs from the evap canister to the rollover valve. There is a little plastic bracket that clips onto the line and holds it back by the fuel filter. Something must have gotten caught there and bent the line because its badly deformed at the clip. I'm going to investigate that today. That plastic line is pretty tough and I doubt that damage I saw would cause it to leak, but maybe I'll get lucky. I've run out of easy things to fix.

I replaced the gas cap 2 years ago. When I replaced it they gave me a cap from another model volvo and recently I've been wondering if thats my leak,,,.they told me it "would work" AND it had a lanyard. It worked well for several years, but its definitely different. I saved the old cap so I can always swap them out and see what happens. The new cap has a lanyard on it and when you look at the white threaded plug part you can see springs and gizmos inside like an over pressure valve (maybe) . The old cap was just a plastic screw in plug with a sturdy gasket. Any thoughts on this

[abscate]

Have you smoke tested this system? Finding a leak by inspection in 20-30 feet of hoses, clamps , connections, components is really tough

[theWIFES_S70]

Before swapping the carbon canister, I would try an oem ($$$) Volvo gas cap... Sigh. Thanks for posting all this 98v70dad. I'm going to tackle our P0455 in the Spring...

[abscate]

Its even more fun trying to trouble shoot these when the EVAP cycle takes 2000 miles to go ready.

[98v70dad]

Before swapping the carbon canister, I would try an oem ($$$) Volvo gas cap... Sigh. Thanks for posting all this 98v70dad. I'm going to tackle our P0455 in the Spring...

I have a new OEM gas cap. I bought it at the dealership. They recommended it as better than the original. It was expensive so I'm not ready to replace it yet since it ought to be OK. The only reason I would suspect it as the culprit is that its not the original part number.

I just replaced the kinked section of plastic vent line tubing with 1/4 rubber fuel line. I doubt that was the problem but I'm going for a test drive to see what happens.

I have learned one thing that might be helpful to others here. The brass fittings they sell for pex water line splices are great for splicing 1/4 fuel line to be used in the PCV system. As a bonus they are CHEAP. If you need to splice 1/4 and 3/16 in a tee you can get a short piece of 1/4 copper refrigeration line like the old school stuff for your ice maker. Reduce the OD of the copper line carefully in a bench grinder and solder it on. I searched everywhere for a plastic tee with 1/4 and 3/16 bars on it and finally gave up and just made one.

[98v70dad]

Its even more fun trying to trouble shoot these when the EVAP cycle takes 2000 miles to go ready.

When I reset mine it comes back within a few days. I don't know if that is a clue or not but it takes me about a month to put on 2000 miles and my codes come back usually after about 100 miles. My scanner which is an ultra gauge is always scanning and it even warns mean that a code is pending sooner than the actual check engine light indication.

I haven't smoke tested it yet but its on my to do list. I figured I would just replace everything since eventually everything would go bad and leak. Its a good approach but its not working for me. I can say for certain this has not been that expensive parts wise but if I had to pay volvo shop rates for the labor it would have already spent thousands. I have no confidence that they would have any more success with this than I have.

I have to make a smoker box and will probably use a home depot paint can. I haven't figured out where I'm going to get a valve stem. You used to be able to buy them at the auto parts store for about $2.

[theWIFES_S70]

I have learned one thing that might be helpful to others here. The brass fittings they sell for pex water line splices are great for splicing 1/4 fuel line to be used in the PCV system. As a bonus they are CHEAP. If you need to splice 1/4 and 3/16 in a tee you can get a short piece of 1/4 copper refrigeration line like the old school stuff for your ice maker. Reduce the OD of the copper line carefully in a bench grinder and solder it on. I searched everywhere for a plastic tee with 1/4 and 3/16 bars on it and finally gave up and just made one.

Wow... what a useful hint, thanks!

You know, we really need a place to put these fixes into a hack database. While not being an OEM fix, your example of making this tee is one of the better writeups I've read on here. Reminds me of the heater hose/heater core hack with 5/8" tubing that, in addition to saving a ton of money, simplifies a vital aspect of our cars.

[98v70dad]

Recap of my efforts

*** Up front - engine area ***
Replaced purge valve with OEM part. I suspect that this part may have died early. I've replaced it twice. The first time it was good for about 2 years. The second time it cleared up all of my PCV issues for a few months and now they are back
Replaced the in line filter next to the purge valve with OEM - some people toss these ... it keeps fine carbon chips out of the purge valve
Replaced everything in PCV system with OEM or mods recommended here - passes glove test easily
Replaced all rubber hoses in engine compartment including the J and U hoses (OEM pArts) on the charcoal canister
Removed and inspected charcoal canister - it was OK - reinstalled
Replaced the shut off valve with OEM part
Replaced the hose to the shut off valve with bulk hose from the auto parts store - don't remember what I used - heater hose I think
Replaced the little plastic fitting with O-Ring that fits into the elbow upstream from the throttle body intake - mine was very loose

*** In the back - near gas tank ***
Replaced tapered vent tube on top of gas tank
Replaced the two short hoses (OEM part) on either side of the roll over valve
Replaced the 90 degree elbow at the fuel pressure regulator with 3/16 fuel line in a looped pigtail
Replaced fuel cap with a non-standard but recommended by the dealer gas cap - had been using 2 years before p0455 came back

*** In my head ***
Studied everything I could find posted here for clues - a little frustrating since there are so many configurations. Still looking for the post that tells how to bench test the purge valve. Read it once and now can't find it again now that I need it.

Figured out how the system works by studying the posts - simple in theory - too many rubber connections to be reliable in practice. It made me realize that if the engine can't produce a strong vacuum for whatever reason the vacuum test of the closed system will always fail because the supply value is too low. I'm thinking maybe there is a leak at the vacuum tree gasket(or something similar) and my supply vacuum is too low to start with. I'd like to check the vacuum at the manifold but I dont know what the vacuum there is supposed to be.

Wrote a poem about it one day out of frustration instead of throwing a hammer or screaming obscenities - will post it if I/we ever solve this mystery

Thanks for the help everybody!

I am going to do a smoke test but I haven't already done that because I need to make the smoker and I wonder how effective it will be for the gas tank area. There's not much left to work on.

[cn90]

I am thinking about "pressure test" instead of "smoke test" (I don't have a smoke machine).
- Basically disconnect the vacuum tubing at the purge valve.
- Connect air hose with appropriate adapter so it fits in the hose.
- Pressurize the fuel system to 5 psi or so and listen for "hissing noise".

Just a thought, too cold now (-20C in Nebraska). Will wait until I get warmer weather to do this pressure testing and report back.
Ideally this should be done inside a garage with everything turned off (no music, radio etc.) and I need to clean my ear wax beforehand so I can hear the faint hissing noise...lol.