I have a '97 F150 with a 4.6 engine. I have noticed at engine start up, an exhaust leak which seem right under the drivers floor board. It seems to quiet down after several minutes but is still there. Tonight it did the same, I had the truck off for about an hour and then started again and it was LOUD. But it was really only loud under acceleration. It seemed to quiet down quite a bit after several minutes. I am assuming it is due to the exhaust pipes expanding/contracting. But I have had this truck for several years and it has never done this before.
I tried to get under the truck but could not pinpoint the location. I also took a stethascope tool and could not pinpoint the location.
I know a lot of owners mentioned there is serious issues with the manifold or bolts on this model.
Can somebody elaborate for me......
Take a hard look at the studs on the manifold. If you find one missing you have found your problem. As the truck warms up the area between the manifold and the head expand and seal up. Don't delay on checking this out! If this goes long enough it will damage the head and then it gets expensive.
I just had my drivers side manifold replaced it had the same problem description you wrote above. Ford dealer wanted almost $800 had a local garage I go to change it out for $510. The manifold itself cost about $170 I think.
My truck is a 1997 F150 4.6L as well with 100k on it.
You might have to replace the manifold or you might not. You wont know untill you get it off and take a look at it. If the manifold is warped you should be able to tell pretty easily.
The nuts are probably going to be rusted onto the studs and if you have broken studs those might be interesting to get off. Mine were rusted so bad that you had to use a smaller socket and pound it on with a hammer in order to get a good bite on the nuts. For the studs were just used lots of penetrating oil and pair of vise grips.
Good luck, chances are you are gonna need it.
torches-patience and luck. even if the manifolds aren't warped, i would replace
them with stainless headers- you get all the hardware and gaskets and much cheaper than the factory manifolds. they will last a lot longer too.
Well, I have not had a chance until now to really look and figure out the leak. It turns out that it is the bolts that connect the manifold to the cross-over pipe on the drivers side. The bolts rusted away in the center. So, there is a portion of bolt nut still on both sides.
Is it more of a "Stud" in the manifold? If so, do you think I can fix without removing the manifold. What would be the best way to get it out? Do I have to drill it out? I've been soaking it in penatrating oil overnite and will add it continuously through the weekend where I'll try and tackle it.
The gap is not too severe, like I mentioned earlier...as it warms up and the pipes swell...the noise is gone.
What would you guys do? I'm not opposed to a cheap fix.
I'd pull the manifold & replace the studs with new ones from ford. They sell stainless studs now that solve the rusting problem. Check your manifold to make sure its not warped before you put it back on. I replaced mine with JBA shorty headers. It took me 8 hrs to change them but it wasn't too hard. Pull the fenderliner & it gives you lots of room
I did the drivers side on mine a year ago, slow going, but does come apart. I don't condone shortcuts, but my old 82 Ford plowtruck had busted bolts at that connection, couple pairs of cheap vice grips sealed it right up, still OK after 3 years when I donated it to a church. In fact I think JC Whitney sells a temporary clamp just for that. I drilled mine out and put stainless bolts and nuts on mine( my 98 that is).