Hiss, pop, bubbling at night underneath

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braptorin

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2019 Gen 2 bought new in Feb of 2020. Has about 7k very light pandy-street-queen miles so far. Essentially a flawless 802A vehicle where I did my first major service about 2 months ago. I've always noticed a slippy trans, but I think that's correlated with cold drivetrain and relatively normal. Recently I've noticed 1 weird failure-to-upshift from 20 -> 40 in autocruise on a highway (got to redline and I took over control), and I've noticed some very clunky shifts when driving extra slow and smooth (as if the clutch was engaged too long and it lurches before the next gear).

Anyway, after a 45 mile drive from OC to LA last night about 10pm at normal highway speeds I got home and parked in my usual spot about 15 degree inclined driveway (tail lower, nose up and out). I hear an uncharacteristic very loud hissing and popping from under the vehicle. This was a dry and cool night, maybe 55 or 60F the whole way. The HVAC was set to auto at 73F, which was essentially heating. Seat heaters engaged, too.

I discovered a lot of hissing and bubbling coming from a connector before the muffler. Note that this has never happened before and I've parked in this driveway in this way for months now.

I took a video and if you listen with the volume up you can hear the hissing (sorry for my grunts, lol). Note that the truck's off and it's dead silent near me so all that background noise is the hissing and bubbling I'm worried about. At about the 30 second mark you can see where I at least found dripping and hissing although that might not be the only location or issue.


Anyone know what's going on? Is this normal?
 
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braptorin

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AC drip hitting your hot exhaust.
I mean... the AC wasn't running though, only the heater. Does that also condense water in the same way (I didn't think that's the case for cars, but perhaps I'm wrong)?

I guess if the HVAC drain is right above that spot then sure, pretty much case closed.
 

isis

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You had two threads.
 

Dane

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I mean... the AC wasn't running though, only the heater. Does that also condense water in the same way (I didn't think that's the case for cars, but perhaps I'm wrong)?

I guess if the HVAC drain is right above that spot then sure, pretty much case closed.
Was your defrost running? That runs the AC compressor to dry the air, so the same as running AC in terms of condensation.
 

rightway

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Several months ago I was reading the F150/Raptor Factory Service Manual, air conditioner/heating section, just to learn how things work. I remember it describing how the system monitors the cab temperature and the humidity. There is a small fan and sensor in the dash, behind an approximately 1 inch square grill/vent on the dash on the right side oi the steering wheel. I had always wondered exactly what that opening was for. Now my guess is the system was running the air conditioner to adjust the cab's humidity as it was warning the air, that being your source of water. The condensation drain is on the passenger side of the fire wall inside the engine compartment.

I will have to admit the dripping water appeared to be coming from joint in the exhaust pipe but it's hard to visualize the exact condensation drain path. It did not have the look anti-freeze, which could have been from the turbo charger.

Watch your coolant levels for a while. Please keep us informed.
 
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