HISSING SOUND and SMOKE

[chetubi]

Hey there…

We are on a long trip though Europe. Lots of borders here. And high temperatures right now.

Now second time it happened with our 08 Ford e350 5.4 V8 QuadVan 4x4 with ARB Lockers that after a long time stop and go in the heat at a frontier, when we were finally through from the rear suddenly a sharp hissing sound occurred (about 1-3 sec) and in the rear mirror I could see like grey/white smoke come blowing out from under the rear of the van. Smelling just a little chemical, oily. Not like gas (Benzin).

Like something spraying the van from underneath or a valve opening.

We have no (propane) gas in the van. It is not coming from the front/engine. Not from the inside. No air tank for the airlocker.

Van driving normal besides that.

What can that be?

Any insight appreciated 👍🏻

[boywonder]

Rear air locker hose? The grey smoke could be moisture in the line?

[chetubi]

Originally Posted by boywonder

Rear air locker hose? The grey smoke could be moisture in the line?

Thx. 👍🏻

Why should the hose act like that with this sudden explosive hissing?

[Twoxentrix]

I had a loud hiss (lasted about 3 seconds) & some smoke - I just had the van serviced a couple days early before a trip. My first reaction was to look at my scan gauge - Trans temp was at 217. When I pulled over and inspected underneath I found a considerable amount of transmission fluid that had evacuated - turned out they put too much fluid in the transmission. The smoke turned out to be the oil that sprayed onto the exhaust.
Did you look under the van to see if you had any visible fluid leaks?

[chetubi]

Originally Posted by Twoxentrix

I had a loud hiss (lasted about 3 seconds) & some smoke - I just had the van serviced a couple days early before a trip. My first reaction was to look at my scan gauge - Trans temp was at 217. When I pulled over and inspected underneath I found a considerable amount of transmission fluid that had evacuated - turned out they put too much fluid in the transmission. The smoke turned out to be the oil that sprayed onto the exhaust.
Did you look under the van to see if you had any visible fluid leaks?

I could not look. It was on the highway.

But also a good point. I will check that.

Thx

[E-350]

Servus! Not sure whether or not this might also be heat related, but I have a current problem that my rear proportioning valve leaks…

Also had a broken transmission tail housing leaks in the past that spilled a lot of oil. See if you have a lot of oil underneath and perhaps a drop hanging at the end of the tail housing.

Hub seals?

[chetubi]

Own idea:

I have loads of anti corrosion fat (Mike Sanders) down there.

It starts to get liquid again when it is hot.

What if just a huge drop culminated at a certain spot and fell down on hot exhaust parts - > hissing and smoke!???

Probably not that clear of a hissing and spray like smoke!? And would repeat more often!?

[carringb]

Originally Posted by chetubi

Own idea:

I have loads of anti corrosion fat (Mike Sanders) down there.

It starts to get liquid again when it is hot.

What if just a huge drop culminated at a certain spot and fell down on hot exhaust parts - > hissing and smoke!???

Probably not that clear of a hissing and spray like smoke!? And would repeat more often!?

If a blob of this stuff lands on the exhaust, it probably does sound like hissing, like dropping grease in a very hot pan.

The only other source of oil I can think of, would be the transmission vent, as mentioned above. I have had this happen as well, also from over-filling, however this has never caused hissing for me, because usually the over-flow is a little more gradual.

I have once had my A/C compressor fail suddenly (and another time had the high-pressure line rupture), and dump out all the A/C, along with the refrigerant. But it was more like a small explosion when this happened!

[Lilnuts2]

Because it's the second time this has happened makes it that much more interesting. Normally I would check the following: Gas shock blow? Underneath spare tire failure? Air suspension bag? non dash AC unit? Charcoal canister passing a stone? Emissions system failure?

Your not getting any codes tossed so it is not a cat converter failure.
If this has only happened when things are extra hot I would scour the exhaust system and look for any stains or places where a vent hose could drop oil on the hot exhaust.

[chetubi]

Thanks for all of your input and ideas folks.

Appreciated! 🙏👍🏻