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Exhaust smell coming into the cabin


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I have an odd problem that I just can't track down and I was wondering if anyone on here has come across it, or maybe had some suggestions I could investigate?


The long and short of it is, I have an exhaust smell coming into the cabin and I cannot find out where it's coming from?


A bit of history:  I have a 1985 Daimler Double Six 5.3 V12; I have had the engine out and rebuilt it, swapped out the injection system for Weber 40IDFs, high lift cams, new valve guides, multi-angle cut valve seats, light skim, branch manifolds, manual gearbox conversion, high ratio rear diff, electric water pump and fans and a Electromotive ignition system (replacing the distributor).  As the carbs have no option to plumb in the crank breather, I have it exiting under the car, by the rear axle.


When stationary, I can stick my head in the engine bay and sniff as much as I like, but I cannot smell anything. When driving, with the windows closed you can't smell a thing, open the window and it's there (As the engine warms up, the smell is more noticeable), but not hugely strong, however there and when I get back, my clothes smell of it.  There are no Oil leaks in the engine bay, no exhaust leaks and no cracked gaskets (all exhaust gaskets are new as of 2 weeks ago).


There is one small leak from the rear crank end cap, but it's minute.  If it were that causing Oil to leak onto the exhaust, then how would it get into the cabin, via the drivers window, even on the motorway at 80mph!  If it were the crank breather, again, being at the back, underneath, how would this find it's way to the window?


I'm at a loss, I cannot find anything?


Any help or suggestions would be very much appreciated.





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Welcome to the club, Tony.


You have far more expertise than I do, and you appear to have covered all the possibilities.


But there must be a reason for fumes being sucked into the car, and hopefully there may be someone with a idea.  There are a lot of experienced member who might be able to assist.





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  • 5 months later...

Are you sure there's no exhaust leak ???

One way to make a check is to get someone to hold a cloth and block the pipe at the back

while ticking over so as to build a preasure in the system-- while you are under the car then 

you can hear the smallest of leaks.???


Just a thought.???



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Its something you should check out as oil leaking  onto a hot exhaust could be the answer ???



Hi Frank,


It has happened twice to me.  A brand new Ford Escort [Company car] delivered to my house and within 50 miles of usage the Oil smell was there.


The second time was when my son's mini was smelling and leaking after a service from a garage round the corner. The gasket on the rocker box was a touch twister,  very simple solution is to do it right.





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  • 3 years later...

Hi, have you used any engine cleaner/degreaser  ?, because I did on my engine and since then I have a bad egg smell in the cabin also, apparently you can use an aerosol foam type cleaner and few days after i used it, it dries like hard wax in crevices and stays there smelling all the time !, I thought if that was the problem it would eventually burn off, it hasn't 6 months later, I have found out since its very common,  there is a guy who challenged a large company to come clean and admit that their products was causing this !, I can't remember the video and where it is at this moment lol, but I assume it's on youtube under valeting/detailing. Hope this helps others that buy these tins of engine cleaners. I thought the same that it was this foam cleaner dripped onto my exhaust,  but no, when you have watched the video you will understand.  Hope this helps someone because the smell is that bad my wife won't use the car now.

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