Exhaust Leak

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Ltine - 19 Aug 2004 00:50 GMT

Hi Everyone,

I have been reading your post for a long time but have never
submitted one until now. I hope that somebody out there can help me.
I have a 68 ford Bronco, Brand new 302cid, 351 windsor heads (bigger
valves), Holley Truck avenger carb, and a brand new bronco c4. The
reason I have posted this message is because I have a problem I just
cant beat. I have exhaust fumes coming into the cab. This may sound
easy to correct at first, but I have already done all of the obvious.
I have replaced both of the mufflers, the pipes only have about 3000
miles on them, and for good mesure I have checked them anyway. I did
the donughts off of the manifolds which (did seem to help a little),
and I have put exhaust tips on just to make sure it is clearing the
back of the truck.
The exhaust system is 2" and it is straight back without a cross over
of any kind. And finally the manifolds are stock but not cracked or
broken in anyway, and have brand new gaskets and I have checked the
torque several times.
However the only time that I have any problem is when the window
is down. I have heard tidbits about a vortex being created by having
the window down, that sucks into the cab. I'm not sure this is true
but any help will be greatly appreciated. Anyone who has ever ridden
in an old Bronco knows that in the summer there is no way to not open
the window or take off the top in the summer. I am truely desperate
here. I am a competative athlete and cannot take the fumes. I'm
afraid that if I cant solve this problem I will have to get rid of my
old bronc, and thats too bad because with this engine set up she
screeams!

Thank you in advance for any help, I throw myself on the wisdom
of the group.

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Steve W. - 19 Aug 2004 01:19 GMT

Reroute the exhausts exits so they dump out the sides. Then look over
EVERY body seam and panel for openings (tailgate and windows also). Plus
you might want to check the carb mix, if it is running rich it will
REALLY create a LOT of fumes. The window being down creates a partial
vacuum inside the truck that then draws the fumes in through any body
seam or opening available.

Signature

Steve

> Hi Everyone,
>
[quoted text clipped - 27 lines]
> Thank you in advance for any help, I throw myself on the wisdom
> of the group.

Reply to this Message

Mike Romain - 19 Aug 2004 14:34 GMT

You need to fix all the rust holes in the floor.

When you open the window you create a vacuum that will suck in fumes big
time if there is any hole or crack.

I also find turning on the heater blower helps as well as opening 'both'
side windows at the same time in my Jeep CJ7. I have a new body tub and
exhaust and still have to be careful about fumes. One window open only
will allow fumes to suck in through the rear window snaps and zippers.

A friend in a Jeep TJ couldn't understand whey he could not stay awake
driving. He had the 3 rear windows out and with the door windows
closed, he was getting gassed bad. I figured it out the first time
driving with him.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

> Hi Everyone,
>
[quoted text clipped - 27 lines]
> Thank you in advance for any help, I throw myself on the wisdom
> of the group.

Reply to this Message

Rick Colombo - 27 Aug 2004 01:50 GMT

When you said it only happens with a window down, my guess is that most
likely you are sucking exhaust in through the rear tailgate area because
the gaskets back there are not sealing tight enough. I never owned an
older Bronco (what we call "EB" for Early Bronco), but I think you have
a lower tailgate and upper liftgate, both of which have rubber gaskets.

This type of problem is not Bronco specific, it can happen to any
vehicle with an openable rear end. You've done so much and seem intent
on fixing this, I suggest you replace all the gaskets back there and see
if it helps. To keep the rubber gaskets in good condition, you should
spray them with Silicon spray a couple times a year. Good luck.
-PapaRick

--------------------------------------------------------------------

> Hi Everyone,
>
[quoted text clipped - 27 lines]
> Thank you in advance for any help, I throw myself on the wisdom
> of the group.

Signature

-PapaRick Colombo@Ameritech.net /Home <or> Colombo@fnal.gov /Work
1972 MGB (Blue/Black top), w/1.8L 4-cyl inline, chrome bumpers:)
1990 Oldsmobile Cutlass Supreme International (w/3.1L engine)
1993 Bronco 351EFI E4OD/BW1356 D44-Ford8.8/open 2"-lift 35"-tires
1996 Jaguar XJ6, w/4.0L 6cyl inline, ABS/Trac_Control, 3.54 gears

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