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Best Tailpipe Routing to Avoid Fumes in Car

4K views 15 replies 10 participants last post by  kbuhagiar 
#1 ·
Hello Folks,

Today was nice and sunny so I drove the 56 with my window down. I noticed a fair amount of exhaust fumes, sometimes while moving but mostly while waiting at traffic lights. My 56 150 two-door sedan has headers, H-pipe, Flowmasters and 2 1/2" pipes all the way out the back and about 1" past the bumper.

If I have an exhaust leak it isn't readily apparent, as the damned Flows, which are on my list for replacement, are LOUD.

Is it possible that the fumes are being drawn all the way up from the back bumper to the driver's side window? Would it be better to have the tailpipes exit after the rear tires?

Thanks in advance.
 
#2 ·
It sounds as though you have the best exhaust routing with the pipes exiting at the rear bumper. Do you have a closed pcv system? Just wondering if while stopped at the traffic signals you may be getting some crankcase fumes inside the car? Or as you said, possibly an exhaust leak?
 
#3 · (Edited)
57,

That's pretty much what I thought regarding tailpipe placement, can't get much better than that. And I have a closed system, definitely not crankcase fumes.

I still need to do a visual inspection for leaks, especially where the collector bolts to the header. But, after further consideration, another possibility is the car is running a bit rich at idle, perhaps giving notice to what would otherwise be normal exhaust fumes. Can excessive ignition advance at idle contribute to this?
 
#9 ·
Can always pour some ATF down your carb to produce a lot of smoke to see if you have a leak.
Might not be a bad idea. :confused0006:
 
#5 ·
Mine exit just below the bumper, just under the frame rails. Never noticed any smell, till one day took friends to the airport with so much luggage I couldn’t latch the trunk, tied it almost closed. It was the worst I’ve ever experienced in any vehicle. Maybe your trunk seal has lost its integrity.

Not related to exhaust, but I did replace the factory seal on the trunk lid w/ a specialty, on the body, better looking, better integrity seal.
Vehicle Car Automotive exterior Auto part Hood

Jim
 
#6 · (Edited)
Mine exit just below the bumper, just under the frame rails. Never noticed any smell, till one day took friends to the airport with so much luggage I couldn’t latch the trunk, tied it almost closed. It was the worst I’ve ever experienced in any vehicle. Maybe your trunk seal has lost its integrity.
Trunk weatherstrip is new and in excellent condition. Note that the picture below was taken when I purchased the car, before trunk seal replacement and trunk lid alignment.

Got a picture of your tailpipe setup?
No pictures of the underside, but here are the tailpipes:
 

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#7 ·
I used to commute 50 miles a couple days a week in a Subaru Outback.
Every return trip would put me quartering to the prevailing wind. Think heading north w/ an onshore breeze from the SW. There was nothing wrong w/ the vehicles exhaust, but I could strongly smell it on those return trips if I put my window down. Not so much of an issue that I ever tried to reroute the exhaust.
Jim
 
#16 ·
UPDATE:

Old thread, but the problem was solved about a year ago after some careful four-corner idle-mixture adjustment, and the addition of a vacuum-advance distributor to replace the POs fully-locked unit. Fume problem all fixed.
 
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