AC/heat sucking in exhaust at idle/while stopped

Exhumis

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Searched the forums but there's tons of posts with my keywords so gave up.
94 7.3L F250.
I'm assuming my issue has something to do with a blend door? When I'm sitting at a stop light almost have to shut off the AC the exhaust smell is so strong inside the cab.
 

Clb

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Down pipe, y pipe, manifolds, and the rest sealed tight?
No way the cowl intake is finding the tailpipe...
The blend door is in the cab.
 

IDIBRONCO

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Another possibility is that it's actually crankcase gasses being sucked in your HVAC system. How is your CDR? Is it sealed up like it's supposed to be? Are you, by chance, running a RDT?
 

Exhumis

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Down pipe, y pipe, manifolds, and the rest sealed tight?
No way the cowl intake is finding the tailpipe...
The blend door is in the cab.
To my knowledge. I'll double check them. Thanks for the info about the blend door
 

Exhumis

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Another possibility is that it's actually crankcase gasses being sucked in your HVAC system. How is your CDR? Is it sealed up like it's supposed to be? Are you, by chance, running a RDT?
New cdr with new o ring, so no rdt.
 

Exhumis

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Down pipe, y pipe, manifolds, and the rest sealed tight?
No way the cowl intake is finding the tailpipe...
The blend door is in the cab.
Can I infer then from your post that our trucks draw fresh air from inside the cowl?
 

Clb

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^^^ this.
The blend door shuts off outside airflow at the firewall from the high pressure cowl area at bottom of glass,into the plenum...
Try the smoke test, drizzle some atf\water SLOWLY into the intake and look for soot leaks.

Disclaimer
This could hydro lock eng. If over done.
 

Exhumis

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Ah ok, I'll try that and see what happens. So is there no way to switch from drawing outside air to recirc/inside air? I don't see anything on the controls that indicates such.
 

chris142

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Move the lever to recirculate and make sure the pot moves the door.
 

franklin2

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The actuator that moves the door to recirculate can be seen over by the pass side hood hinge. The little plastic line to that actuator loves to get brittle over time and break. You can usually find a good spot down in the harness, and then just run small rubber hose from there to the actuator to fix it.
 

Exhumis

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Well thanks guys, max ac fixed the issue. Didn't realize that was recirc and I don't have the manual for the truck.
 
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