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Volvo- Gas Tank leak ON TOP of tank, How in the world?

My boyfriend has a Volvo with 100,000+ miles, not exactly sure what year, but he recently found out the Gas Tank has a leak- ON TOP of the tank. We scratched our heads and tried to figure out how this happened. How did this happen? He does normal city driving, hasn’t have an accident or bump into anything. He took it into the mechanics and they said it would be around 3000 repair/replace. Can someone shed some lights into how the tank got a leak on the top?

Thanks so much.

My first thought is that the $3000 quote is ridiculous. I’d recommend a second and third opinion on that.
As for how, tanks have many seams on them. Not sure what his tank is built like, but I’d guess that one of the seams, either a tank seam itself or a joint to the filler neck/sending unit has probably worked loose.
Also know that there is a lot of plumbing associated with gas tanks now. The vapors they give off are collected and stored, then eventually piped back into the engine. All those hoses and lines are subject to deterioration, and can cause fuel leaks. Are you sure it’s not one of them?

You didn’t give a year or model for the Volvo, but it’s quite typical for all of the tank’s outlet stuff, including the fuel pump to be on top of the tank. The fuel pump is sealed with a gasket. The fuel lines connect to the fuel pump sealed by o-rings. And then there are the evaporative emissions lines that carry the gas fumes. Any of those things can leak. So my first guess is that it isn’t the tank itself, but something that is necessarily attached to it. But the result is the same. You have to drop the tank.

The filler neck attaches at the top too and can leak in various ways, but that usually doesn’t mean dropping the whole tank.

Hi all,

The car is a 2005, Volvo s60 2.5t awd turbo.

as the matter of fact, the whole tank just got dropped. we’re waiting to hear the real verdict.

Here’s a parts diagram for the gas tank. Note how many things are up there that can leak:


Unfortunately, I think the guys that diagnosed that $3000 leak may not be entirely competent

Had they used an evap/smoke machine, they probably would have known exactly what was leaking before the tank was dropped

I’ve dropped many tanks to do fuel pumps and senders. And I’ve also fixed many evap leaks, some of which were the filler hose or the sender seal. Many times, the smoke machine showed me where the leak was before dropping the tank

A leak on top is not an unusual occurrence! If you live in an area with lots of snow and slush, this stuff gets thrown against the underside of the car and a lot lands on top ot the tank, which often is shallow in the middle.

The salt stays and cause corrosion.


But if this car uses a plastic tank . . . and I’m guessing it does . . . then the snow and slush shouldn’t have an effect


Is the tank made out of plastic?

Can you provide us a picture?

I’ve seen this happen on steel tanks; IF the Volvo has a plastic tank (gold plated, it seems) then the leak could be at the junction of where the lines go into the tank. Extremes in temperature also could cause cracking, although Volvos are supposed to be cold weather cars!


If it has a steel gas tank, dust and dirt can accumulate on top of the gas tank. This dust and dirt attracts moisture. Since the gas tank isn’t exposed to the sun so this moisture can’t evaporate it’s stays on top of the gas tank longer. This then causes the top of the gas tank to rust out.


@db4690 and Docnick,

Thank you both for your advice. I will have to get more information on the gas tank.
I’m in Louisville, KY and we don’t have that much snow to deal with. This year is probably the coldest we have experienced, but there isn’t much snow compared to the rest of the country.

Will be back!

@Tony and @CigRoller - Thank you for your insight into the issue as well.