2005 XC70 engine just got a whole lot louder

EamonnMR · Post by **EamonnMR** » 31 Oct 2018, 11:49

I was driving under normal circumstances this afternoon and suddenly the engine is way louder per unit RPM. I'm a bit worried about driving it, but I don't get any dash lights and am close to home. Engine looked normal (ie no fuel spraying everywhere.) Bit worried about an exaust leak.

EamonnMR · Post by **EamonnMR** » 31 Oct 2018, 12:02

Made it back without incident, muffler appears to still be in place. Anywhere else I should be looking for damage besides just under the car in general?

Georgeandkira · Post by **Georgeandkira** » 31 Oct 2018, 13:44

Is it louder overall? It sounds like you're focused on exhaust noise so I suggest driving it up on ramps and safely get your head around as many places as you can.

Have you opened the hood and again, moved your hearing apparatus (ears) around the engine bay?

Sometimes you can feel the escaping gas if it is exhaust leaking. Just be careful not to get burned and watch out for the belt.

Post by **abscate** » 31 Oct 2018, 13:55

Put an Idaho potato on the exhaust tip at idle and see if the noise changes and you can localise.

Dont use an Iowa potato - it can ruin your wheel bearings.

( a thick pad of rags will work too)

EamonnMR · Post by **EamonnMR** » 31 Oct 2018, 15:30

Upon closer inspection under the driver's seat

That might be the problem.

Post by **abscate** » 31 Oct 2018, 18:01

Yeah, those leaves are going to go crunch crunch crunch, for sure....

Georgeandkira · Post by **Georgeandkira** » 01 Nov 2018, 06:13

From your initial post: "...way louder under RPM..."; that'd fit.

Seize the opportunity to install a fuel nozzle and igniter to create a rear facing fire blaster....do the smoke boys one better!
Do watch those dry leaves.

Post by **abscate** » 01 Nov 2018, 07:04

That looks like it will just bolt back up with a new gasket?

TheMrFailz · Post by **TheMrFailz** » 01 Nov 2018, 09:11

When your car just kinda casually straight pipes itself.

Post by **oragex** » 01 Nov 2018, 09:23

EamonnMR wrote: ↑31 Oct 2018, 15:30 Upon closer inspection under the driver's seat
IMG_20181031_171053.jpg
That might be the problem.

Yep, my 2003 didn't completely fail, but the two bolts at the flange between the catalytic converter and the front silencer were well rotten and one was already failing. One needs to drill/grind the studs out and either buy the same studs or use exhaust black bolts (picture) - regular white bolts will just seize in there and will need to be cut next time, even the stainless steel ones. The original studs are pressed in (cone head) and are impossible to punch/press out. New gasket also needed - any car shop will have it.

But the biggest issue here - and this is for all cars - is that the flange on the catalytic converter side starts getting eaten by rust and develops a gap at the lower point. I had to grind-sand the flange on the cat side to make it level again so it doesn't leak.

While there, may as well remove the nuts (just the nuts, leave the studs in there) at the exhaust manifold - flex downpipe flange, and replace them as well with the nuts in the picture.

Got an old video, at about 10:00