Stopping a leaking exhaust manifold from entering the cabin air | FordForumsOnline.com
  1. Welcome to FordForumsOnline! Our community is here to help you with any questions you have related to your Ford. If you are looking for a friendly community to hang out with other Ford owners you can look no further than our forums here! Registering is easy and free!

Stopping a leaking exhaust manifold from entering the cabin air

Discussion in 'Ford Crown Victoria' started by bradleyheathhays, Jan 10, 2019.

  1. bradleyheathhays

    bradleyheathhays Member

    Joined:
    Dec 6, 2017
    Messages:
    123
    Likes Received:
    6
    Location:
    Lexington, KY
    I have an '11 Vic that's leaking exhaust right where the exhaust manifold connects and the problem is it's getting into the cabin by way of the air heat / vent system. When the cars moving I get no exhaust in the vents at all. It only happens when I'm sitting still. For the time being (cold weather), instead of fixing the exhaust I'd just like to block the outside cabin air intake. Here's a pic taken through the outside air vents on the pass side right above the blower motor..

    ai.imgur.com_Lg8fH9s.jpg

    Is the wire mesh opening seen under the vent fins the only intake for the cabin air? My best idea is to cut some kind of hard plastic to match the shape and attach it with plastic epoxy resin. Exhaust smell in the cabin is fairly strong. Are there any other openings into the vent system I should be concerned about?
  2. Iowan

    Iowan Well-Known Member Respected Member

    Joined:
    Oct 5, 2018
    Messages:
    1,312
    Likes Received:
    251
    Location:
    North central Iowa
    The best and ONLY fix is to repair the exhaust leak!!! It is not that hard of a repair and hopefully your life and the person that you hit after you pass out at the wheel from carbon monoxide poisoning is worth the cost of the repair. Just fix it!
  3. bradleyheathhays

    bradleyheathhays Member

    Joined:
    Dec 6, 2017
    Messages:
    123
    Likes Received:
    6
    Location:
    Lexington, KY
    I agree, but time, money and outside conditions are all against me right now.
  4. bradleyheathhays

    bradleyheathhays Member

    Joined:
    Dec 6, 2017
    Messages:
    123
    Likes Received:
    6
    Location:
    Lexington, KY
    I assumed it would be a difficult repair. What happens when an exhaust manifold leaks at the engine interface? What needs to be replaced...only a gasket possibly?
  5. Dominick 1

    Dominick 1 Well-Known Member Respected Member

    Joined:
    Dec 26, 2014
    Messages:
    6,478
    Likes Received:
    873
    Location:
    Parkersburg Wv
    2d358ca03d4439622c21aa9371149ec1[1].png
    #2 is your exhaust manifold gasket
  6. Iowan

    Iowan Well-Known Member Respected Member

    Joined:
    Oct 5, 2018
    Messages:
    1,312
    Likes Received:
    251
    Location:
    North central Iowa
    A certain amount of care has to be taken not to break the studs in the heads. Other than that its strait forward, I would think the manifol needs to be tŕued.
  7. Action

    Action Moderator Staff Member Respected Member

    Joined:
    Mar 22, 2014
    Messages:
    12,625
    Likes Received:
    1,464
    Location:
    Phoenix, AZ 85008
    Assuming the HVAC doors all function correctly ...... By changing the HVAC mode to recirculate outside air is no longer introduced into the vehicle interior.

    A door will close that prevents outside air from entering the HVAC system. This is commonly done in MAX AC. Most newer vehicles have a RECIRC button. If not then operate the HVAC system in MAX AC with the temp control on hot. I believe the HVAC does re-circulation with the system set to defrost.

    >>>>>>>>>>>Aciton
  8. Action

    Action Moderator Staff Member Respected Member

    Joined:
    Mar 22, 2014
    Messages:
    12,625
    Likes Received:
    1,464
    Location:
    Phoenix, AZ 85008
    To answer your question about the mating surface between the exhaust manifold and the engine block, Ford used gaskets in some applications. Looks like your engine uses individual gaskets versus a gang gasket.

    If there is an exhaust leak in that joint there are several fixes.
    The bolts holding the manifold are defective. Tighten or replace bolts/nuts holding manifold. However that could brake a bolt or stud.
    Manifold is warped. Replace manifold. OR resurface manifold.
    Or gasket was exposed because the connection was loose. Replace gaskets and bolts/nuts.

    >>>>>>>>>>>>>>>Action
  9. bradleyheathhays

    bradleyheathhays Member

    Joined:
    Dec 6, 2017
    Messages:
    123
    Likes Received:
    6
    Location:
    Lexington, KY
    The mechanics that used to service the fleet of vehicles this one used to belong to were really reluctant to fix this type of exhaust leak so I always assumed it was a difficult job. Glad to know it probably won't be so bad. I'll probably have a professional mechanic break those bolts loose though. I'll give it a quick shot but I don't have the heat to do it.

    Unfortunately I've been told elsewhere I shouldn't do the intake mod because the exterior intake is the only way air gets into the car from the heater and AC coils. Is this true? Best I can tell there's an air re-circulation intake vent in the pass floorboard. I was just planning on wiring that permanently open.

    I do remember one of the mechanics one time mentioning there's no way to cut off the outside air intake flow, so I dunno.

    Years ago I'd heard that MAX AC made the system go into recirc mode but I'm not sure about this vehicle. I'll definitely try it though and see if it works.
  10. bradleyheathhays

    bradleyheathhays Member

    Joined:
    Dec 6, 2017
    Messages:
    123
    Likes Received:
    6
    Location:
    Lexington, KY
    Well the vent twidling part went well. It seems that my internal intake door wasn't opening at all so I disconnected it and wired it open. I would imagine that since everything blowing through the vents was coming from the outside that this probably exascerbated the exhaust smell problem a good deal. After wiring it open the overall airflow was a lot better.

    For the external intake I just covered it with a zip lock bag and a big tile grout sponge. The reinstalled cowl holds the sponge in place, should work well and it'll be easy to undo.

    Unfortunately the exhaust wasn't leaking so I wasn't able to do any effective testing. There's some duct work that runs from the fan to the center of the firewall. I wonder if a break somewhere in that could be the cause.
    Last edited: Jan 11, 2019
  11. Action

    Action Moderator Staff Member Respected Member

    Joined:
    Mar 22, 2014
    Messages:
    12,625
    Likes Received:
    1,464
    Location:
    Phoenix, AZ 85008
    Max AC and recirculation are the same thing.
    This function closes a door in the HVAC system to block in coming air. The door is usually vacuum operated and normally open.

    The difficulty in removing any exhaust manifold that many are reluctant to do is breaking a bolt/stud in the cylinder head. Since that is an area of high heat the bolts/studs are subject to a lot of stress. They rust over long period of time making the removal process difficult. The difficulty is multiplied with a bolt/stud breaks as that fix typically results in cylinder head removal.

    >>>>>>>>>>>>>>>>>Action
  12. Iowan

    Iowan Well-Known Member Respected Member

    Joined:
    Oct 5, 2018
    Messages:
    1,312
    Likes Received:
    251
    Location:
    North central Iowa
    I pull a 30' camper with my Expedition and on one trip I blew out one exhaust gasket, I was surprised that I was able to remove all hardware without breaking anything, I did use heat and let it cool before removing and I did have the manifold resurfaced. I have done several Chevy truck LS manifolds at work and the bolts often are broke before repairs are even made. But I highly recommend repairing the exhaust leak!
    Action likes this.
  13. 1971FordLTD

    1971FordLTD Member

    Joined:
    Dec 8, 2018
    Messages:
    74
    Likes Received:
    10
    Location:
    The Woodlands, Texas
    If your manifold is cracked (forgive me if this ain’t the problem), you could always put some high heat JB weld on it as a temporary fix.

Share This Page