Question about the 2001 Ford F150 4.6L V8.

With the fan and AC not used at any time during driving, I am seeing wisps of gray smoke drifting out of the air vents. I can't identify the smell since it is weak.

Also a family member said they saw that fluid had dripped onto their driveway from the engine compartment where I had parked, and they thought it was AC compressor fluid but weren't sure. I haven't been able to get underneath the truck yet but I haven't used the AC at all until I get it looked at.

My main question is (1) whether there is any chance driving it like this is bad for the engine, and (2) what it might be given the symptoms. Also, (3) this isn't oil smoking, is it? I just changed the oil a couple of weeks ago and it looked normal, and the truck is running fine with no error codes. I am not sure if it is possible for smoking oil to get into the blower system.

I don't intend not to fix it, but I just can't get to diagnosing it and lining up the parts until next week. I just want to make sure I don't hurt the engine. I don't know exactly how the coolant/heater system works enough to understand this problem.

 

White smoke ? Maybe even the grey I see you mention now, was that a quick edit or am I going blind

Leaky heater core. Probably.

 

Is it bad for the engine, assuming I check on coolant levels?

 

It might cause more problems in the system as crap circulates. I had an old beater I let a leaky heater core go for a while and the only issues was a greasy windshield and a worry about breathing that crap in. I drove around with the passenger window down to pull it away from me. I was young and stupid. Never noticed any engine issues or other coolant leaks.

...but I'd fix it sooner than later now

 

Bad heater core. Mine did this when it blew.

Jim

 

There seems to be a consensus that this is the heater core, but here's the twist:

These wisps of smoke behave more like faint cigarette smoke than water out of a kettle. They're wisps, but they hang in the air a good 20-30 seconds (windows are up and blower is off). So unless hot coolant "steam" behaves like this, it seems a lot more like a combustion byproduct. I'm not clear on where in the heater core combustion would happen, unless parts of the heater core are well over 300-400 degrees. So I'm wondering whether something in the air system is actually burning (the AC compressor) or if there is something more serious going on in the engine. Any ideas?

 

It is possible that some debris (leaves) or critters (bugs or bigger) have found a hot spot (a relay or something) to settle into and they are smouldering when it's powered. Or maybe some overheating wiring (frayed or chewed or pinched) is smoking the insulation.

As I recall the smoke from my heater core was more of a fog than wisps as you describe so you might be right thinking it is something else. Maybe someone else has another possible cause.

Are you seeing the smoke with the engine cold ?

 

No, it doesn't seem to produce the smoke wisps cold, just when the vehicle is warm.

I did however notice that the coolant reservoir was empty, and I realized I've neglected this part of the truck (haven't had it that long though). The truck's engine temperature has never gone into the red, even idling while hot, but I'm going to drain and flush it and get that system squared away. I don't think it's related, but I figured I'd mention it.

Anyway I'm still open to ideas from others, too, on how smoke particles could exist in the air system and whether it could be coming from the compressor somehow, even though all fan/heat ***** are off.

 

That PROVES you have a leaky heater core. Don't bother with a drain and flush till you fix it.

 

Well, I'll be damn, I added some water to the reservoir and it's not emitting the smoke anymore. Not saying there's not a problem, but more coolant helped a lot. I'm also not seeing any exterior or interior leaks, but I'll keep checking. Going to drain/flush/redo the coolant anyway since I still have to drive it before I can do any repairs.

 

I have this bookmarked in case, and thought it might help you. Save you a search anyway, though there might be other good posts too.

https://www.f150online.com/forums/19...placement.html

EDIT: Heh, you were posting the good news while I was posting this. Not sure anything is actually fixed but hey, if it ain't broke no more