Burning smell coming through vents into cab

Ahhh thanks, didn't even think of that. My coolant level appears to be normal, when I take cover off radiator the fluid level right at the top. I believe I have read somewhere that if you suspect air in the coolant lines/radiator, to take the cover off and park on an incline with truck running and it should somehow cycle the air out of the system. I may try giving that a shot.

Thought of this, no oily residue in my coolant fluids and checked oil and appears to be no water mixed in with oil or on dipstick.

This also crossed my mind, but it is definitely not a dead rotting flesh type of smell.

This is not the issue, I have no leaks coming from the valve cover....have sat and watched it for about a good 10 minutes while the truck was running.

But I haven't been using my AC, only heat. Smell actually dissipates when I change it from hot to cold air, but smell is still slightly there....much worse when blowing hot air.

 

The A/C compressor actually comes on in defrost mode.

Probably not the problem, but it’s worth checking it and ruling it out. The clutch going out is a fairly common problem on the 2nd gens, and the rubber burning up produces that god awful smell you described.

 

ok....was not able to burp any air out of coolant system. I have noticed that when I first turn the truck on and turn on the heat, the smell is at it's worst and very noticeable. As the truck runs or if I switch from hot to cold air, the smell dissipates. I'm thinking it is almost definitely a problem associated with the heater core. Guess it'll be another trip back to a mechanic shop and see what they can find as I'm at a loss as to what the problem is.

 

Nasal Ranger FTMFW!

 

After thinking further, you might want to...
1. take another closer look for engine leaks between engine and firewall. Tough to get a good look, and worth checking again. Mauybe even try to point light from bonder truck to this area. Look for older dirty spots, should look more like dirt build up that liquid.

2. Check other hydraulic systems, power steering pump pump/lines, brake system (ABS unit is at passenger side near firewall I believe), and tranny cooler lines, radiator, and cooler if you have two pkg.

3. Look at your PCV valve, and other items connect to and that transfer fluids around engine.

Leak doesn't have to be big, just an occasional drip onto a hot surface will cause the smells.

 

There's a freakin' tool for everything!

 

Like I mentioned this was my problem, I discovered it in the middle of winter because defrost mode uses the AC compressor

 

I don't use defrost mode though, always have it on heat.

 

I don't think it's a leak at all. As I mentioned, smell almost completely dissipates when I turn the air/heat off. I'll crawl back under it tomorrow and look again from the underside up at back of engine/firewall.

 

Since the smell dissipates as the engine warms up, seems to me that there might be a worn seal somewhere that's letting grease or other fluids escape out when not warm, maybe on the belt or just due to higher friction/temps on part itself.

Maybe try looking for dirt clump near rotational bearing surfaces, pulleys/shafts, etc. Or try carrying a remote temp gun and do a quick scan when smell starts up?