98 V70: P0455: Gross Evap Leak

[sleddriver]

The gremlin is back. About the time I think I've slayed this dragon, she rears her ugly head once again.

I think the code is P0455.

First, does your empty tank emit a WHOOSH when you open it to refill? Mine stopped doing this a long time ago..so long I can't remember when. I remember mentioning this to my mechanic, but he asked about the gas cap. That was too easy to check. I had it done at an inspection station. OK.

I spent half a day on this last year, using a small air brush compressor, checking valves, hoses, the charcoal canister, the tank. I pressurized the fuel tank with air and heard it stretch. Thus I assumed one of the many hoses on top were not rotten. I removed the charcoal canister and both pressurized & pulled a vacuum on it. I have not dropped the tank for a visual inspection.

I attempted to make a quickie smoke tester with some incense in a jar as the air source to the pump. But the smoke wasn't dense enough coming out to rely on sight, so I listened for hissing noises and sniffed for incense. No joy. I didn't want to drop the tank unless I heard hissing.

I discovered the valve on the fan shroud would fail to hold vacuum when driven with a repetive one second pulse. I replaced it with a new one, the CEL cleared and all was well for several months.

But now the dreaded P0455 dragon is back and I'm stumped. I'm thinking to let my mechanic take a crack at this since he (a) has a lift and (b) a smoke machine.

I also wonder if a leak in this sytem could affect gas mileage. Any ideas?

Anyone dealt with this code before? What worked for you?

 

[GumbyJarvis]

GAS CAPPPP!

Happened to me, even though it didnt appear damaged, change it, clear the code..

The Swoosh not being there when opening the gascap makes me think it is the gascap..
Though you may inspect it, a tiny pinhole could be the cause, Plastic/Gaskets wear out over time...

Stant gas caps are like 9$ and some change at AAP.

 

[sleddriver]

As I stated, it's the first thing I checked. If it WAS the cap, it wouldn't have stayed off for months.

Next?

 

[GumbyJarvis]

It COULD be the cap man, My last cap threw a code, I cleared it, turns out 3 months later it popped back on, upon further inspection, the gasket had a needle size hole in it.

Rubber + Gasoline/Ethanol = Weaknesses

 

[Volvohead]

This is so common on these, it's not even funny.

Of course you can replace the usual suspects (tank cap, purge valve, etc.). But to do it correctly, there is really only one way: a professional smoke test.

I've had hoses buried in the fender gap develop leaks in these, and all along the line from the tank to the canister they can leak. Even a bad connection from the purge valve to the intake can set it off, as the Volvo's EVAP tolerance is so sensitive. Too sensitive, IMO.

A leak will not affect mileage or engine operation in any way, provided there is not a major vacuum leak on the engine side of the purge valve. It's an emissions & safety feature only.

Here's a tip: The evap system will not cycle (or throw a code or MIL) if the fuel tank is kept close to full. But everything else will eventually cycle following a clear, provided you keep the tank full.

Of course, if you ever detect the faintest whiff of gas fumes, get it to a shop ASAP, as something more major may be open.

 

[artificialist]

Originally Posted By: Volvohead
This is so common on these, it's not even funny.

Of course you can replace the usual suspects (tank cap, purge valve, etc.). But to do it correctly, there is really only one way: a professional smoke test.

I've had hoses buried in the fender gap develop leaks in these, and all along the line from the tank to the canister they can leak. Even a bad connection from the purge valve to the intake can set it off, as the Volvo's EVAP tolerance is so sensitive. Too sensitive, IMO.

A leak will not affect mileage or engine operation in any way, provided there is not a major vacuum leak on the engine side of the purge valve. It's an emissions & safety feature only.

Here's a tip: The evap system will not cycle (or throw a code or MIL) if the fuel tank is kept close to full. But everything else will eventually cycle following a clear, provided you keep the tank full.

Of course, if you ever detect the faintest whiff of gas fumes, get it to a shop ASAP, as something more major may be open.

It is my understanding that Volvo didn't decide how sensitive the leak detection had to be, the EPA and CARB did.

 

[Astro14]

I don't know about this chassis...but on the P2 cars (like my 2 ) the J-hose that comes out of the leak detection pump is notorious for failure...might not see it visually...

There is also a software update (I think) that changes the threshold for the LDP to set the code. I understand that on the P2 chassis (again, not yours) it was super-sensitive and set false codes often...

I would go to IPD ( www.ipdusa.com ) for replacement parts, they have everything that you would need to do the job once you find the leak.

 

[Volvohead]

On the money, Astro14.

While the Gov sets the limits, Volvo's software was a little too aggressive in the implementation to standard.

The later P2s had the same hair-trigger programming that was corrected with an ECM update. There was a TNN for them.

Not so on the earlier ones. We're stuck with them. So if you look at them funny, they go off.

In the grand scheme of things, it's more of an annoyance than anything else.

 

[sleddriver]

Originally Posted By: Volvohead
Of course you can replace the usual suspects (tank cap, purge valve, etc.). But to do it correctly, there is really only one way: a professional smoke test.

Yea..I don't throw parts at a problem. Too expensive and it puts "prescribe" before "diagnose". A smoke test puts the 'diagnose' first. I may experiment more with making a DIY smoke tester. My mechanic is currently quite busy.

Quote:
A leak will not affect mileage or engine operation in any way, provided there is not a major vacuum leak on the engine side of the purge valve. It's an emissions & safety feature only.

I question this. A vacuum leak is a vacuum leak. I wonder if this could be one reason for declining mpg reports in older Volvos. One rationale for getting this fixed, so I can test out my theory.

BTW, no Volvo owners have answered my question re: WHOOSH!

Quote:
Of course, if you ever detect the faintest whiff of gas fumes, get it to a shop ASAP, as something more major may be open.

I have noticed this recently for the first time one morning: Very strong smell of gas in the garage. That got me to thinking. I think the tank is vented to open air via charcoal canister via the shut-off valve. So the strong smell of gas means something is leaking bypassing the canister.

But it hasn't happened again, even after filling up. Which is odd. Overnight, everything would cool down and contract, possibly causing a leak. But why only once? Odd.

 

[sleddriver]

Originally Posted By: Volvohead
On the money, Astro14.

While the Gov sets the limits, Volvo's software was a little too aggressive in the implementation to standard.

The later P2s had the same hair-trigger programming that was corrected with an ECM update. There was a TNN for them.

Not so on the earlier ones. We're stuck with them. So if you look at them funny, they go off.

In the grand scheme of things, it's more of an annoyance than anything else.

+5 on annoyance...I'll escalate to RPITA! The search for smoke continues. . .

 

[Volvohead]

Originally Posted By: sleddriver

I have noticed this recently for the first time one morning: Very strong smell of gas in the garage.


I'd get that puppy to a shop without delay.

Fumes, even once, spells trouble.

Let me know how it goes.

 

[sleddriver]

Originally Posted By: Volvohead
Originally Posted By: sleddriver

I have noticed this recently for the first time one morning: Very strong smell of gas in the garage.


I'd get that puppy to a shop without delay.

Fumes, even once, spells trouble.

Let me know how it goes.

I have a really good chance of rain this weekend, so my outdoor projects are on hold. I might jack up the rear (since the sled is garaged) and have a look.

I was on fumes this afternoon, so only put in 5ga in case I decide to lower the tank. Since this is an area I haven't spent much time in, it's gonna be dirty and I clean up dirty areas before I put it back together.

I DO look fwd to finally getting at the root of this & I'll be posting my findings. This one's been a burr in my saddle for quite sometime.

 

[mechtech2]

Smoke only test for external leaks in lines, NOT internal crossover leaks in valves and such.

 

[sleddriver]

Originally Posted By: mechtech2
Smoke only test for external leaks in lines, NOT internal crossover leaks in valves and such.

Roger. It's times like this I wish I owned a lift...

 

[mattd]

these cars break hoses everywhere. Check them ALL. common ones are the vent hose (larger hose) and the small purge lines in the engine bay.

 

[JOD]

I'm assuming you aren't smelling fuel, which means you can rule out the sending unit/fuel pump gaskets?

If so, here's my suggestion: replace everything, J-hoses, all the vacuum lines, and elbows, etc. I totally get the desire to "not be a parts replacer", but you're about to travel down the road I have so many times with stuff like this, only to end up wasting a bunch of time. Let's say you finally find it and fix it...only to have it come back, just like you have already. It's not that the fix didn't work, it's that you have a new leak.

The vacuum connections on this car seem to be good for about 15 years/150K, give or take.So, my guess is that if you invest a bunch of time finding it, you'll have another leak 6 mos. down the road. I'd invest the energy in just replacing everything. Odds are very high that there's a pinhole leak in one of the hoses. What's the worst that'll happen? You'll have all new vacuum hoses! You look like you're in it for the long haul with this car, so that's the route I'd go. This is analogous to fixing a broken spoke on a bicycle wheel: break one, replace it...break a second one? rebuilt the wheel, because they're just gonna keep breaking.

 

[sleddriver]

Quote:
I'm assuming you aren't smelling fuel, which means you can rule out the sending unit/fuel pump gaskets?


I HAVE smelled gas the next morning upon opening the garage about twice. Never on a regular basis though.

Quote:
If so, here's my suggestion: replace everything, J-hoses, all the vacuum lines, and elbows, etc.

Throw new rubber/silicone at it, eh? That's mostly done in the engine compartment, per my note on my other post. Remember, this is a GROSS leak. . don't think pinholes would trigger that.

Smoke test should find multiple leaks at once.

Also no current/past Volvo owner has answered my question: Did your tank go WHOOOSH when opening to refill? They must not...otherwise owners would be bragging about it. . .

Wow do I miss simplier cars...w/o all the emissions bravo sierra from the EPA. I'd like to 'flip-on' their CEL! [/rant]

 

[JOD]

Originally Posted By: sleddriver


I HAVE smelled gas the next morning upon opening the garage about twice. Never on a regular basis though.

....

Also no current/past Volvo owner has answered my question: Did your tank go WHOOOSH when opening to refill? They must not...otherwise owners would be bragging about it. . .


I actually missed the part about the "whoosh" sound, but the two things listed above make it very likely that it's the gasket on the fuel sending unit--which unfortunately is in the tank. A friend of mine had this issue and I helped him drop the tank, which solved it.

Thing is, my R always had a bit of a "whoosh" on opening the cap, but I never got an evap code on that particular car. I figured it was normal.

Originally Posted By: sleddriver
Wow do I miss simplier cars...w/o all the emissions bravo sierra from the EPA. I'd like to 'flip-on' their CEL! [/rant]


I have to say, more electronics, fewer vacuum lines has made things better, though obviously they introduce their own set of problems. Personally, I'd rather deal with the electronics!

 

[sleddriver]

Quote:
I have to say, more electronics, fewer vacuum lines has made things better, though obviously they introduce their own set of problems. Personally, I'd rather deal with the electronics!

The 98 wagon has FAR more vacuum lines than my previous 85 SAAB 900, and both are turbocharged.

To me, 'modern' cars are needlessly complicated, which makes them more expensive to buy & service & repair & own. Which is probably why leasing is so popular!

Back to troubleshooting. . . .

 

[sleddriver]

Found this description of the EVAP system operation:

"When the EVAP canister shut-off valve is closed the fuel tank system should be sealed. When the EVAP canister purge valve is activated the fuel tank pressure must fall to a set negative pressure or it will be interpreted as a major leak. Then the canister purge valve closes. Fuel tank pressure must then remain within certain limits or it will be interpreted as a minor leak. DTC ECM-4308 is stored if the CM registers a minor or major leak"

Possible Source(s)

Major Leak
Leaking fuel tank, filler pipe, fuel tank filler cap, EVAP canister, EVAP shut-off valve or lines between these compnents.
Blocked EVAP valve.
Blocked hoses to the fuel tank pressure sensor or defective fuel tank pressure sensor. Does not react to changes in pressure.

Minor Leak:
Leaking fuel tank, filler pipe, FT filler cap, EVAP canister, purge valve or lines between these components.