Exhaust Leak
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From: Tulsa
Exhaust Leak
I have a very slight exhaust leak where the exhaust manifold meets the head at the number 3 cylinder on my 95 F-150 with a 300 I-6. What is involved in fixing this problem? I am assuming this will entail adding exhaust manifold gaskets; it looks like it may be quite a chore. Any thoughts?
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Exhaust Leak
You have to remove the lower intake & the exhaust manifolds , Its not too bad removing it all , Getting all those bolts back in & torquing them in the proper sequence is the fun part . If it was my truck & it was just the manifold that is warped , Id replace them both with new ones . Check the head for any signs or warpage while the intakes are off . If the head is the problem then not a whole lot is going to stop the noise problem . Plus , using gaskets on the exhaust manifolds because they are considerably thicker than the lower intake gasket , cause cause problems torquing all the bolts . Its very easy to break the ears off the aluminum lower intake if things are in a bind or if the surfaces that the bolts contact are uneven . The lower intake is pricey too , about $250 for $5 worth of aluminum . The torque specs on the lower is 22 to 32 Ft Lbs & 25 Ft Lbs is plenty to keep things secure .
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From: Tulsa
Exhaust Leak
I was told by a friend who happens to be a Ford Mechanic that it is next to impossible to get the old manifold installed properly without having both the manifold and the head resurfaced. His suggestion was to attempt to re-torque the manifold bolts but I'm afraid this may break the bolts and then I'd be in a mess over a little noise. He also suggested I check for leaks in the emissions control equipment which pipes into the exhaust system; he claims this would be a more probable location for a leak on a truck with only 87,000 miles on it. I wonder if headers would be a better solution to this problem?
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Exhaust Leak
The air injection pipe will lead one to believe that they have an exhaust leak , Often the little tubes from the pipe that screw into the head will crack & break . This isnt a constant exhaust noise either , you will only hear it when the vehicle is moving & sometimes the noise will go away when the engine gets to normal operating temp ... Is this the case with your engine ?
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From: Tulsa
Exhaust Leak
No, not the case with mine, it doesn't go away when the engine reaches normal operating temperature. I notice it while driving and when I'm down fairly hard on the throttle. I can't hear it at an idle nor while revving the engine in neutral. I only notice it when the engine is under a load. I recently bought the truck and it looks like the AIR injection system has been replaced but it could just be clean. What do you think?
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Joined: Jul 1999
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Exhaust Leak
If you only hear it while driving then Id almost bet its the Air Injection Pipe . The reason it may disappear when the engine is hot is because the thin metal those tubes are made of & the heat causes the metal to expand sealing off the leak , for a time anyway . The crack gradually gets to the point where its too big to seal . Replacing the air injection pipe is much easier that replacing manifolds etc .
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Junior User
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From: Tulsa
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Post Fiend
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From: Metro Detroit (Redford)
Exhaust Leak
Someone posting at FTE had a manifold leak on a '65 F100 with a V8. They has jammed some of that liquid steel stuff in the leak area and it seemed to quiet it down. Might want to try a cheap fix like than. Can't hurt and if it works it saves you a lot of hassle. Or depending on if it's not too loud, just let it be.
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Junior User
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From: Tulsa
Exhaust Leak
I got under there tonight and started looking around. It is really hard to tell anything just by looking. I was told to get the engine hot, then suck a quart of ATF in thru the brake booster vacuum line and turn the engine off for one hour. After one hour start the engine then the smoke will point to the leak. Any other suggestions for checking the air tube and egr tube for leaks? If I have to remove the upper intake, do I need any special tools? Seems like I remember needing one. Are there any "tricks" or special wrenches needed to remove air tube? It appears the tubes are at a sharp angle relative to the top of the head. I'm thinking once the upper intake is off, the air tube won't be a problem. Any help you can give me is most appreciated. When I tear into this I won't be able to have the truck down for more than a few days so I want to have a good idea what I'm getting into before I get started. It seems the leak is getting worse, my truck sounds like a wore out 30 year old farm truck going down the road. Thanks.
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Exhaust Leak
The hardest part of removing the upper intake is disconnecting the egr pipe . Id be leary of dumping ATF in there , I dont think the O2 sensor likes ATF . From what you have described it really sounds like the air injection pipe , My exp has shown the No 6 tube of that pipe is the one that breaks & causes the exhaust noise .
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