Exhaust fumes

I am trying to figure out why I am getting exhaust fumes inside my car. 1965 Chrysler 300 383 cid , driving around town no problem , but out on the road above 45 mph exhaust fumes get into the car. Now here is the kicker first speed above 40/45 drivers window down no fumes but open the vent window can fumes the same with the passenger side windows, open all 4 no problem no fumes. If I use the ac no problem.

It done this with theold exhaust with was bad, so last fall replaced it all from manifolds back, replace single exhaust with

dual set up . I bent and installed this myself checked today no leaks found. The tail pipes are appx 2/3 inchs passed the bumper with turn downs. There are no holes in the body new weather strip on trunk. I also smoked tested the exhaust no leaks along with smoke tested the interior with no signs of leaks.

I don't know where else to look is this a case of air pressure??

Did you put it on the hoist and hold a rag over the tailpipes with engine idling while someone checked for leaks? There is something wrong someplace.

If there are no exhaust leaks there is one (very unlikely) possibility. The trunk rubber seal is shot, and at certain speeds there is a vacuum formed at the back of the car that sucks the exhaust into the trunk and up thru the car. I told you it was unlikely but barely possible if the tailpipes are too close to the middle of the car.

If there are no exhaust leaks there is one (very unlikely) possibility. The trunk rubber seal is shot, and at certain speeds there is a vacuum formed at the back of the car that sucks the exhaust into the trunk and up thru the car. I told you it was unlikely but barely possible if the tailpipes are too close to the middle of the car.

First I don't think it's as unlikely as Rusty does. I've been in cars where this happened, most notably a friend's very similar 1968 Dodge Polara sedan.

Second, this may also happen if there are rust holes undetected in the underbody of the car in the vicinity of the tailpipe. I had this happen in an old Subaru daily driver once. Also if there's a missing body plug somewhere this can happen.

It did this with the factory signal exhaust the pipes come out where factory would, It does have new seal on trunk. Being that I work in a dealer ship we have a smoke machine for looking for leake in emission syatems with adaptors for looking for water leaks which I used but could find nothing.

I may crawl into trunk close lid and look for light coming thru. I don't crawl into trunk without a screw driver or pliers so I cn get back out when they wont open trunk!!

Well if the body is perfect and the exhaust is perfect there are 3 possibilities.

You were driving at 45 with a 50 MPH tail wind and it blew the exhaust forward into the car.

The smell came from the car in front of you.

It is your imagination.

I'm guessing there is an exhaust leak. Or, maybe an oil leak burning on the exhaust manifold that smells like an exhaust leak.

We all have access to the 2 Million watt portable lights that sell for about 15 dollars at Walmart. Try putting one of these in your trunk and with the trunk closed when it is pitch dark out ( in your garage ) climb under the car and look for light. It worked for me !

Wayne

Exhaust manifold leak?

Phil

Seems like either a manifold leak or a small oil leak at one of the valve covers onto the manifold. Is the heat riser intact and functional ??

The big block Mopars are famous for valve cover leaks because the outside of the cover is right next to the exhaust manifold, and yes that smell could be confused with exhaust smell.

I would also take a good look at the intake manifold, exhaust manifolds for that matter although I would think you would hear any leaks there.

Blow by may be your problem. Rum the motor at around 1500-1800 rpms with the hood up you may see the exhaust gases.

I found the problem brought the car in the shop today crawled into the trunk put up on lift turned on 12million candel power lamp no holes. so I started up front looking for a oil leak, and since the 383 has an open manifold, usedthe bore-a-scope looked under manifold low and behold there is a small hole in the valley pan.

Removed manifold found that it had rusted thru right in the center so under low vac it was splashing a small amount of oil on to the under side of intake right where the exhaust crossover is burning off the oil. It must have not had enough to leak out as to where I could see it and it would drain back down into engine..

As far as I can tell its never been apart has pentastar embossed on the pan.

thanks for all the tips going to replace tomorrow and recheck

One of the easiest manifolds to replace. No water and no distributor.

yep hadit off in 20 minuets just wating for valley pan parst store ha gaskets but no pan should be here tommorw

I found the problem brought the car in the shop today crawled into the trunk put up on lift turned on 12million candel power lamp no holes. so I started up front looking for a oil leak, and since the 383 has an open manifold, usedthe bore-a-scope looked under manifold low and behold there is a small hole in the valley pan.

Removed manifold found that it had rusted thru right in the center so under low vac it was splashing a small amount of oil on to the under side of intake right where the exhaust crossover is burning off the oil. It must have not had enough to leak out as to where I could see it and it would drain back down into engine..

As far as I can tell its never been apart has pentastar embossed on the pan.

thanks for all the tips going to replace tomorrow and recheck

Well I'll be damned. Never heard of that before. Now I don't feel bad that I could not diagnose it from 1000 miles away.

not a problem there rusty, but I did go back out to the road where the problem. drove backward 40/50 mph smell still there not the tail wind , while driving backwards looked in rear view mirror no car so car in front nope, imagination well lets not go there, smell coming from me mmm lets just say I wear them charcoal skives .

but I looked into everyones ideas , sometimes the simplest things are right in front of your face and don't even see them!!!!

thanks to everyone

The valley pan is the gasket.