Climate control causes smoking?

[minig646]

Hey guys,
every winter I get smoke from under the hood. It's consistently from the corner closest to the passenger seat, and was consistently when the heat was on. Now, it's happening whenever the air conditioning is on.

My sense of smell sucks, but the oil level is fine, all climate control features work, and the engine doesn't overheat. The car is a 1999 SLE v6 with 128,000 miles. Anyone have any ideas?

[ThurzNite]

Need better description, but here's what I'm thinking. Assuming you mean steam when you say smoke.

When the engine is hot or while you're driving, it could be the bypass hose, leaky, cracked, ruptured. The heater core is right by the passenger foot area. This's my best guess. Hoses go bad, and the inlet and outlet is right up against the firewall, so vibrations can cause the inlet/outlet holes to vibrate and crack.

If it's when you're stopped, you're thinking radiator, like radiator, radiator cap, thermostat, radiator drain plug, thermostat gasket leak. But you said from passenger seat, so not likely, or remotely thermostat or gasket.

Just for kicks, hows your radiator fans, do they turn on when you're stop and go traffic? And how's your water pump, is it time to replace it, is it leaking?

Dr J

[minig646]

Thanks Dr J, but it's thick and white and smells like something is definitely burning. However, the engine temp is fine (even after a 200 mile drive in the heat with the windows down and no ac). So I'm pretty sure the water pump works fine. As do the cooling fans.

You're the third person to suggest hoses, but how would a leak near the heater core hoses burn antifreeze? It's so far from the block. I guess I could just replace both hoses going to the heater core. It's cheap and easy enough to be worth a shot.

[02slera]

maybe the belt is slipping. smell like burning rubber? you need to pop the hood and turn on that ac and get a better idea where exactly this "smoke" is coming from. "the corner closest to the passenger seat" is not very specific. try and find the source.

[minig646]

Sorry I'm not able to be more specific. The problem is whenever I have time to fiddle with it, it decides to work perfectly lol... my mom borrowed it this morning and it smelled awful, but when she got home I drove it and it wasn't making a scent. That's why mechanics can never help me- the symptoms are almost impossible to recreate on demand.

I didn't think of the belt. I'll check it tomorrow. I think I'll also take a look at the valve cover gasket. It's sweating a bit, so maybe some oil is dripping onto the rear manifold.

[ThurzNite]

Have you ever opened your radiator cap with a hot engine? I haven't, but I've been told boiling hot liquid shoots out. What's boiling hot liquid? Steam.

Ever smelled coolant/antifreeze? Smells nasty.

Ever see an overheated car at the side of the road? What's billowing out of the engine bay? White smoke.

Those are the objective facts you've described and I've correlated. As for "thick", that's subjective, dunno what to say about that.

Maybe coolant isn't your issue, but sure sounds a lot like it. I'm happy to guide you to other possible diagnosis if you're absolutely sure it's not coolant related. Lemme know, no hard feelings.

Dr J

[minig646]

No, I get ya. I appreciate the help. I did a little experiment to make sure I've got my burning fluid smells straight. You're right that it should be coolant, but I'm confident that it's oil. My level isn't dropping noticeably so I may just let this go for now.

It is strange that it only happens when the heat or ac is on AND it's oil, not antifreeze.

[SpeedySolara]

I'll also take a look at the valve cover gasket. It's sweating a bit, so maybe some oil is dripping onto the rear manifold.

You hit the nail right on the head! You're probably smelling it when the ac is on because the vent is open. Here is how to check if its your valve cover gasket:

1. If there's sweating, check if your exhaust manifold is wet. If it is, then you have a leak and it'll burn the oil at startup. Check this before you turn the car on.
2. You'll only get smoke when the car sits over night but if its leaking really bad then even after a couple of hours of the car parked, it'll smoke again.
3. This won't change the vehicle temp or cause a CEL so your dash wont indicate something is wrong. Finally, the smoke should be a white/faint gray color and should last about 2 minutes.

I hope this helps. I put my money on that its your valve cover gaskets. Good luck.

[TheGreenDutch]

mine leaks and it stinks. The rear VCG points downward right over the exhaust.

[minig646]

Its a little sludgy around the rear valve cover... I thought that might be the problem until I saw how hard it would be to fix and consequently decided that it wasn't the problem anymore...

As long as the smoking continues being pretty rare and if I check my oil often, you think I can just let this go?

[SpeedySolara]

Its a little sludgy around the rear valve cover... I thought that might be the problem until I saw how hard it would be to fix and consequently decided that it wasn't the problem anymore...

As long as the smoking continues being pretty rare and if I check my oil often, you think I can just let this go?

That all depends on whether you could deal with it but I'm getting the feeling you have it in you to "let this go" for a little bit longer lol.