Exhaust fumes inside truck

Hello everyone,
Dan here and I'm new to the site. I have a 2013 Tacoma base, 4 cylinder automatic and the truck sits quite a bit sometimes for months on end.
A few weeks ago I took it out as I had to drive down to Pittsburgh to pick something up that would not fit in my Yaris,(imagine that right!). As I'm going down the road with the heater on I smell fumes pretty bad coming out of the heater vents. The smell persisted throughout the whole trip enough to where I had to drive with the window open quite a bit for the whole trip.
Any ideas as to what to look for? I don't smell anything outside the truck and it doesn't sound loud as in an exhaust leak. the truck only has 40k on it.
Any suggestions as to what to look would for be helpful versus taking it to the dealer and them charging me a thousand dollars for nothing.
Thanks,
Dan.

 

No damn idea

 

Muffler bearing!! Sorry man, had to..

 

Check your cab filter for 'stuff'. Was the recirc button on or off?

 

Are you sure it's not rodent urine?

Pretty common for mice to take up residence in unused vehicles.

 

Perhaps the old banana in the tailpipe trick?...

(On a serious note, in addition to the above suggestions, i'd look under the hood for something dripping onto something that gets hot)

 

Sitting for months...

Rat / Mouse in vent filter.

 

If it is truly exhaust fumes, here is the order in which I would go through the rig to look for a leak.

While cold, start the engine and use a lighter/flame or something that will smoke ( incense,sage, greasy rag...) and use it to around the exhaust manifold. If there is a leak the smoke will move in and out (if the leak is big enough) flame will do the same. if nothing, check the collector mount with the same procedure, on down the pipe inspecting every joint or connection.

one thing you did not mention is the exhaust pipe dump location, is it in the same spot as stock or is it a straight run right under the bumper?

straight pipe out the tail is known to leak into the cab as the fumes are picked up by the vortex that is created from the air flow over the cab and into the bed. The newer ram trucks have a modified exhaust/bumper configuration that reduces/eliminates this.

You may just have stench from animals and stuff as mentioned above.

there have been things like cracked exhaust manifolds on the 4 cylinder engines that don't reveal themselves until hot.

 

OP did you ever figure this out? I just changed my valve cover gasket, the job was easy. But right after I noticed exhaust coming in when the heat is running and I am at idle. Any ideas TW?

Man I haven't logged in a while lol

 

How bout them Dawgs! I haven't been this excited since 1980.

 

A lot of times it's an oil leak making it onto the exhaust that you smell. Check the valve cover gaskets, see if it is leaking on the ex manifold.

 

if its coming from the heater vents, the fumes must be coming in from the intake under the wiper blades located on the cowl. this is where all air is taken into the HVAC for heating or cooling

 

Sure haven't! looked the truck over and don't see anything out of the ordinary. It's setting in the garage for now. Like I said before it sets quite a bit, that in itself might be the problem. I have a Yaris I drive daily and am saving the truck for when I retire to North Carolina. Let me know if you figure it out, Dan.

 

I'm very pumped to be as far along as we are. Anything else is icing. Still pumped about getting rid of Mark for Kirby!

I changed my valve cover gasket and then this smell of fresh exhaust when the heaters on started occurring.

Nice, will do dan.

 

This is what I'm thinking. Considering the life this truck lives, it's possible the cats are clogged... would probably not be the sole cause of exhaust fumes but might be a contributing factor.