I posted this is the wrong place before, so here it is:

2004 1500 5.7 SLT 4 door
First off, I did a search for "exhaust fumes" and got some stuff about the gas tank box and lines. Not sure if that's my problem.

I can smell exhaust fumes when the AC or heat is running, doesnt matter if I am stopped or not, but seems to be stronger when at a red light. I've taken it to 2 shops and one cleaned the engine and checked the pipes and found no leaks or dripping oil. I replaced the EGR because a code for it was briefly thrown once. Cheap fix, but no help. Do these have secondary air pumps?

honestly, the truck has 110k and with the exception of interior deterioration and dents, it's a good running vehicle. Blew a tranny at 109 but had it rebuilt. I dont want to buy a newer rig, but if I cant get this fixed, I am going to have to. And then I cant buy a bigger boat

Thank in advance

 

I'd check for any seeping of fuel on the feed lines. Basically you're going to pull any fumes from the cowl area into your cabin, unless you're recirculating the inside air. I did a quick web search, someone reported their fuel pump corroding at the top producing a small leak that made the truck smell like gas. That fuel pump problem seems epidemic, found a few posts on that in the past. But I'm thinking your problem is under hood and you're pulling in the fumes through the cowl area.

 

Thanks for the reply. Once thing is that it doesnt matter if Im on recirc or fresh air, it still smells. However, i dont think the vent/door/whatever that is supposed to isolate recirc from fresh air has ever worked. When the system is off, I can still feel air coming through the vents, always has done that, ever so slightly. However again, with the system off, I do not get the fumes, only when it is on. It also doesnt smell like gasoline, it smells like exhaust fumes. One shop said the exhaust system was tight, though.

i will scour around for leaking lines.

 

I'm at a loss on the exhaust smell. If there is a hole in front of the cats, you would have noticed the noise well before any smell. Blow-by would smell like exhaust. Maybe the crankcase is venting to atmosphere? Not sure how the pcv system works, I've never serviced that on a 5.7. Looking at rockauto, there seems to be a rectangular(?) grommet, hose, and valve related to the pcv on a 04 1500 hemi.

The recirc door issue is unrelated to the smell, but very common. The door has likely separated from its shaft, and has dropped down into the bottom of the cavity. That is why its always pulling air from the cowl, the path isn't blocked off. That is what happened to my 04 1500; I just pulled the door out because it decreased the flow. I never got around to replacing it before I decided to sell it off due to bed side rust.
Lot of info on the hvac doors this page... http://heatertreater.net/dodge-ram-02-08

 

Thanks again for the reply. That vent door is not going to be fixed lol. That's more work than I care to do

 

Even on MAX air, your system will still pull a little air from outside. That became standard around 1972 or so. It's to keep fresh air in the cabin for safety. I'm a little confused with your post. The header says gas fumes and you talk about exhaust smell. For gas, I'd say you have a leaky fuel rail or injector. As for an exhaust smell, I'd look at the EGR system. An exhaust smell from the rear of the vehicle will smell much different because of the catalyst system. Unless you'd deleted your catalytic converter (if you did that, naughty naughty!) you will only smell raw exhaust from the hood area. I don't have a 5.7 so I can't go out and look at my engine to see how the EGR is routed. It's usually near the throttle body.

 

egr on the 5.7 is at the front passenger side of the head, if I remember right. 2500s don't have egr, just the 1500.

 

As a scientist, gas to me is different than the liquid version we put in pur tank lol. Sorry for that, but yes I mean exhaust fumes.

I replaced the EGR a couple months back as that was my first thought. But it didnt help. However, I didn't look into any of it's other components. My exhaust system is stock, ive never modified or replaced it.

The truck did come with a cold air intake and the previous owner just put a mushroom filter on the vent instead of routing it back into the the pipe. I might change that today and see if it helps. Might do it just because its silly looking lol.

Thanks for the new replies. This thing is a head scratcher

 

When I saw you mention as a scientist and gas is different to you, I had a thought. (Really!) If you put a plasma TV in your house, you'll probably burn your house down. Sorry, bad joke.

 

I have heard of issues of manifold bolts getting broken from heat off the cats,,passenger side cat is close to manifold, perhaps you have small leak on that side letting fumes in around cabin air filter which is at top of cowl under hood, an filter may need replaced ,,something to check