When using heater, thick exhaust smell coming from air vents

I realize when you use the heater you aren't using the recirculate feature of the ventilation system, but if we are just sitting for a second (at a light or whatever) with the heater on the smell of the exhaust is thick inside the cabin (as well as the smell of oil since I have an oil leak).

It is obvious to me since I have an all new exhaust piping system, from the heads to the rear, that there is exhaust leaking in the engine bay and I suspect it is at the point where the exhaust manifolds connect to the ypipe (both sides). I'm gonna stuff a bunch of muffler putty in the flared crevices where these connect together (at some point) and hope that makes a difference.

Where is the heater air intake vent on the Windstar and is it the same for where the a/c air comes in as well?

When I have had my cowl off before, I've noticed on side of what looks like some sort of air intake vent there is a large crack along the side of it, but I have never been able to determine this was a crack that went all the way through or just superficial. Is that the same spot where the heater air goes in?

Any other thoughts or ideas? Every time I stop while using the heater, I now turn it off till I get moving again. Smells that much.

Also, is there an air filter in the ventilation system in the van?

I'm betting that you're getting exhaust going thru the cabin filter and into the cabin from the engine compartment. If there's a big crack I'd be checking there but honestly, the exhaust leak is your first priority. I'd be taking a look at the leak pronto.

Consider recycle cabin air instead of fresh/carbon/burnt oil air from the engine bay.
It could be as simple as needing new valve cover gaskets.

Consider recycle cabin air instead of fresh/carbon/burnt oil air from the engine bay.
It could be as simple as needing new valve cover gaskets.

No its not that.. this is a nearly new engine.

I'm sure this is the exhaust leaking where it attaches to the Ypipe because the exhaust pipes were always just a lil bit too big for the exhaust manifolds... they are flared at the wrong lengths and widths just a tad.

I just really would like to know where the air enters the cabin.

I'll fix the exhaust leak as soon as I can, but its been there for years now.

According to my manual:

Outside air is drawn into the system from the cowl, through the blower inlet into the A/C evaporator housing

The only difference is how much air goes through the heater core.

Oscar.

Ok thanks.

What about a cabin air filter? Do our vans have that?

A filter is not going to protect you against carbon monoxide poison.

I know for sure mine has it, but don't know if earlier models do.

To narrow it down a bit, try using "Max A/C" and see if the smell goes away. That setting recirculates the air instead of pulling from outside.

I remember my Pontiac would smell weird when turning on the A/C. I always used MAX A/C until I read somewhere that it causes mold to buildup faster than other modes.

From that moment I decided to use the normal A/C from time to time to help with the smell (read that somewhere) and it really has helped with it. No more nasty smells from the A/C.

To prevent the mold, just turn off the a/c and run outside air for 15-20 seconds before you shut off the vehicle. That dries out the evaporator.

My suggestion was just to compare other settings to max a/c to try and pinpoint the source, not to run max a/c all the time.