Exhaust Smell In Cab

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Charlie

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Bought my truck in 2015. Had original exhaust manifolds and single exhaust. I could smell exhaust in cab when stopped at stop sign and red lights. Driving I do not smell it. Since then, both manifolds have been replaced. Most recent, Friday, had complete new dual exhaust from manifold to near rear bumper and still have exhaust smell. I am at a loss as to where smell is coming from. Using AC or not, still have it. Any suggestions?
 
Shorty81

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Check your pcv valve. If it's not venting correctly you will get door in the cab. That happened to me years ago and I thought it was exhaust.
 
1987 GMC Jimmy

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If you’re not running cats, and bear in mind your blower is running a little bit all the time since it’s got that older ventilation setup, it makes sense to me that a little odor once in a while is normal. I know when I sit at a stoplight long enough, and my HVAC is running 90% of the time, I’ll smell it. I just figure it diffuses quickly and gets sucked in once it wafts over towards the windshield. That or I’m just slowly dying of CO poisoning, and it’s par for the course.
 
Charlie

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Shorty81 said:
Check your pcv valve. If it's not venting correctly you will get door in the cab. That happened to me years ago and I thought it was exhaust.
Click to expand...

So, pcv venting crankcase can cause exhaust odor in cab? I can't imagine that would do that, but I will replace anyway to see. They are a cheap replacement. I can't remember if I replaced that since I bought it. I have cleaned it. I will give it a try.
 
Charlie

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Looking for more suggestions.
 
Preston

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Any holes in firewall, floor? Outside vents leaking air? Good luck
 
DoubleDingo

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Possibly a small leaks from the valve cover(s). Had that happen. Thought it was exhaust, took it to a muffler shop to have it checked out. He shined his light up there with the truck on the rack and said it was a the valve cover leaking. Sure enough. Replaced the gasket, and the smell went away. Could also be a small exhaust leak at the donut or butterfly. But I just re-read your original post and saw you now have duals, so my guess is valve cover leaking and the oil burning off.
 
Charlie

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DoubleDingo said:
Possibly a small leaks from the valve cover(s). Had that happen. Thought it was exhaust, took it to a muffler shop to have it checked out. He shined his light up there with the truck on the rack and said it was a the valve cover leaking. Sure enough. Replaced the gasket, and the smell went away. Could also be a small exhaust leak at the donut or butterfly. But I just re-read your original post and saw you now have duals, so my guess is valve cover leaking and the oil burning off.
Click to expand...

Valve cover gaskets replaced 2 weeks ago. All new exhaust last Friday.
 
Charlie

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Preston said:
Any holes in firewall, floor? Outside vents leaking air? Good luck
Click to expand...

Do not know of any but there could be and none that I'm aware of.
 
DoubleDingo

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Donut, butterfly gasket? Maybe let it get good and hot, pop the hood, and sniff around?
 
DoubleDingo

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Or they didn't get a good weld on a joint. I recall someone on here having that problem after getting new exhaust installed. Took it back in after spotting the leak, the shop welded it up and no more leak.
 
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Had the same problem, and it was the gas cap. The old one was easy to twist/click and turned yellow on the threads. Replaced it with Stant from Wallyworld for $5, and the smell went away.
 
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