Wood smoke

[nic55kel]

Driving along in my truck today when I start to smell wood smoke.
Look around for someone with a bonfire - nothing.
Realise smoke is coming through vents in dash and getting quite strong.
Shut truck off and pull over.
Disconnect batteries.
I can see smoke rolling up the windshield on the inside.
slowly clears up and phew! Thought I was about to have a cab fire.
Check under hood - all okay.
Inspect under dash - cannot find anything that looks out of place???
Reconnect batteries and start it up and watch for smoke - nothing.
Check all instrumentation, wipers, blower, lights - all okay
Decide to drive along slowly see what happens -
takes a while for smell to vent completely but no more smoke.

In over 40 years of driving have never had anything like this before.
I have had electrical fires in vehicles before and this was definitely wood smoke???

I think maybe a twig or small branch must somehow of got against the blower
squirrel cage and ignited from friction. I do kind of remember the ticking sound
like a leaf going through the fan.

Will pull blower motor in morning see if I can see anything.

Anyone else have anything similar to this?

 

[vegas39]

Driving along in my truck today when I start to smell wood smoke.
Look around for someone with a bonfire - nothing.
Realise smoke is coming through vents in dash and getting quite strong.
Shut truck off and pull over.
Disconnect batteries.
I can see smoke rolling up the windshield on the inside.
slowly clears up and phew! Thought I was about to have a cab fire.
Check under hood - all okay.
Inspect under dash - cannot find anything that looks out of place???
Reconnect batteries and start it up and watch for smoke - nothing.
Check all instrumentation, wipers, blower, lights - all okay
Decide to drive along slowly see what happens -
takes a while for smell to vent completely but no more smoke.

In over 40 years of driving have never had anything like this before.
I have had electrical fires in vehicles before and this was definitely wood smoke???

I think maybe a twig or small branch must somehow of got against the blower
squirrel cage and ignited from friction. I do kind of remember the ticking sound
like a leaf going through the fan.

Will pull blower motor in morning see if I can see anything.

Anyone else have anything similar to this?

Not sure about our trucks but on some vehicles, the blower motor resistor is mounted in the air stream and can occasionaly burn leaves and crap that gets in there.
My old VW Rabbit was the same way, had a bunch of leaves that got in and everytime one would get against the resistor, it would burn and smell like brush fire.

 

[6.9poweredscout]

yep, i'd bet a furry critter made a nest and the resistor caught it on fire. happened to my 85. I pulled he blower motor and it was packed full of bedding and leaves and such. warped up the hvac box too. lucky it did't burn my truck to the ground!!

 

[franklin2]

The resistors for the blower motor do get red hot, they will set leaves and other stuff on fire. Sometimes it gets so bad it melts the duct housing. I see you have a 86, which has the slotted holes around the wiper area. On the later trucks they went to a cowl piece with small round holes which helps this problem.

 

[NO_SPRK]

had this happen to a truck that lived in oregon its whole life. dried it out in cali heat and yeah one day i smelled burning... like campfire :-D

 

[Mulochico]

Mine did the same thing a few years ago. Many years accumulation of leaves, etc. Cleaned it out, new resistor, no prob.

 

[Oog]

Once my truck hits 88mph I go back in time to when the interstate was a forest, and I incidentally light a few fires ftom the super hot manifolds.


But thats just me

 

[84TD]

That exact thing happened to me in my 84. I freaked out and stabbed a hole in the housing with my knife and poured water down there. When I took it apart later it was packed full of leaves.

 

[nic55kel]

I wish my truck would hit 88 mph

 

[nic55kel]

Well pulled heater motor and resistor today to see what I could find.
Definitely a few leaves in there and also strong smell so I am confident that is what it was.
Behind the blower there is a flapper valve that switches between recirculated air and outside air and behind the
outside air opening is a downwards cavity. This had quite a few leaves and other things in it
so I vacuumed it out and hopefully that is the end of the problem. In the attached picture the
door (right side) is positioned for outside air and the cavity is below the opening on the left.
It is about 10" deep and seems designed to catch crap that gets through the slots in the cowl.

You must be registered for see images attach

 

[franklin2]

The driver's side also has the downward cavity, and there are drain holes at the bottom. It's good to keep them cleaned out so it won't rust.