Help with evap leak above fuel tank in 07 XC70

**BrickDriver** · 12-03-2020, 04:35 PM

I've been chasing an evap system leak for some time now. After replacing the gas cap, the leak detection pump, and the engine bay solenoid, the leak still remains. The code is ECM-434C Fuel tank system, leakage - Major leak. So I finally took it to the dealer for a smoke test and they found that the leak is at the filler neck vent pipe or filler neck above the gas tank. To replace the filler pipe, the rear sub-frame has to be removed/lowered and the labor is quite extensive ~2k USD (at the dealer).

I'm wondering if the leak could be repaired without dropping the tank - maybe a hose clamp needs tightening, or a minor crack in a hose can be taped, or epoxy can be used repair a crack, etc. Can the top of the tank be accessed without dropping it? Has anyone done a repair like this themselves?

Another option is to put tape over the check engine light......

Thanks,
BrickDriver

**FirstVolvo** · 12-03-2020, 06:04 PM

Do you know where the leak is? The top section of the fill tube appears to be all metal so if a minor crack then a possible epoxy fix if you can get to the area. I did a search and there's not much out there but did find some good information in the link below from Jimmy57. Like he says, you don't have to completely drop the rear suspension but it's still a lot of work. It would help to know exactly where the leak is and if you can get to it some way.

https://www.matthewsvolvosite.com/fo...hp?f=1&t=38931

**BrickDriver** · 12-04-2020, 02:47 PM

Thanks FirstVolvo. Some good info in the thread you referenced - thanks for pointing me to it.
I don't know for sure where the leak is - the dealer says it is the filler neck vent pipe or filler neck above the gas tank, but it may be that the smoke was coming from up over the tank and they may have assumed it was from the filler neck. I may try to get a borescope in there to see if anything obvious can be observed.

**FirstVolvo** · 12-04-2020, 03:26 PM

Originally Posted by BrickDriver

Thanks FirstVolvo. Some good info in the thread you referenced - thanks for pointing me to it.
I don't know for sure where the leak is - the dealer says it is the filler neck vent pipe or filler neck above the gas tank, but it may be that the smoke was coming from up over the tank and they may have assumed it was from the filler neck. I may try to get a borescope in there to see if anything obvious can be observed.

Here's another link with information about a fix for a fuel leak without removing the tank. The mechanic was able to replace a rubber connection and I'm assuming it's the fuel filler neck to gas tank rubber hose connection.

https://www.matthewsvolvosite.com/fo...448856#p448856

**pbierre** · 12-04-2020, 05:08 PM

Originally Posted by FirstVolvo

Here's another link with information about a fix for a fuel leak without removing the tank. The mechanic was able to replace a rubber connection and I'm assuming it's the fuel filler neck to gas tank rubber hose connection.

https://www.matthewsvolvosite.com/fo...448856#p448856

It's more likely a crack formed in a plastic weld, where a hose bib attaches to the tank.

**pbierre** · 12-04-2020, 05:56 PM

Originally Posted by BrickDriver

Thanks FirstVolvo. Some good info in the thread you referenced - thanks for pointing me to it.
I don't know for sure where the leak is - the dealer says it is the filler neck vent pipe or filler neck above the gas tank, but it may be that the smoke was coming from up over the tank and they may have assumed it was from the filler neck. I may try to get a borescope in there to see if anything obvious can be observed.

When you fill the tank 100%, do you get raw gas leaking out?.....You should be able to see a gunk trail where the leak point starts.

When I got my smoke test at a repair shop, costing $145, they said "top of the tank". I took it back and made them repeat the test, noting that I wanted the leak pin-pointed within a few mms, so I could make a repair without dropping the tank. They let me observe the smoke coming out. It was a micro-crack in a plastic weld, the one where the filler VENT HOSE's hose bib is welded to the tank. It's disappointing that Volvo went to plastic tanks and used plastic welding on it....those welds are a vulnerability.