Sounds like an exhaust leak, but… maybe just snow?

[Klutch9]

I ran into something very strange this morning. Our area got about 1.5 - 2” of snow overnight, and it was the heavy wet stuff. Temp right around 32 degrees F. I had to leave early for a job this morning so the roads were largely unplowed. I had driven for about 10 minutes when I entered the interstate, trundling along in the slush at about 65 mph. This was really heavy slush, I could hear it being flung up onto the underbody something fierce. Over the next minute or so I felt like I heard a car near me with an exhaust leak. However, no one was near me that long; I was passing most people (winter tires FTW). Suddenly I realized that the loud exhaust was me!

About 5 mins later I got off the interstate, onto some backroads, and the noise was still there. Over the next 5 mins though, the noise went away. Was what I was hearing just ice packed onto the body/exhaust causing some weird resonance? I had something similar happen a few years back on a cold start at like 0 degrees F. I drove a lot today and checked a number of times, even on subsequent “cold” starts, and no exhaust leak was present.

 

[Kuato]

FWIW, once upon a time, I had an exhaust system - from the muffler all the way to the back - come off in heavy slush.

Might not matter, but which vehicle?

Either one could have a rusted exhaust system....have you had a chance to inspect yet? If it's not sound [pun intended] then more slush driving and the noise will likely come back.

 

[Lubener]

Have someone hold a rag over the tailpipe end and then go underneath and check for leaks. I bet you will find one.

 

[TCL]

May have been slushy snow buildup in wheel liners from tires slightly rubbing.

 

[SwampSurvivor]

I would put my money on a fenderberg falling off and getting stuck in a wheel well.

 

[Astro14]

Slush hitting one side (say, the bottom) of the exhaust system and cooling it, while the rest remains hot, can cause the pipes to flex/bend from differential expansion.

Google “Volvo Rain Squeal” in which the hot exhaust gets hit by cold rain, bends upwards (cold bottom contracts while the hot top stays expanded) and contacts the spinning driveshaft.

Slush hitting your exhaust could cause it to distort and rub, or open a joint.

 

[Klutch9]

FWIW, once upon a time, I had an exhaust system - from the muffler all the way to the back - come off in heavy slush.

Might not matter, but which vehicle?

Either one could have a rusted exhaust system....have you had a chance to inspect yet? If it's not sound [pun intended] then more slush driving and the noise will likely come back.

Ah, yes I should have mentioned that it’s the van. I don’t think it was ice rubbing on the tires since the sound changed with RPM, not with speed.

 

[Kuato]

So -- what did you find?