Do you have headers or cast iron manifolds? The manifolds don't usually get a gasket believe it or not, they will seal against the head but if the mating surface is pitted that may not happen in your case.
The EGR tube should not pull ouf of the connector, the end should be a flared like a brake line and it's that flare that seals and prevents leaks, sounds like you need a new line.
Cheap gaskets suck, spend a little more and you'll get a better gasket that also fits better. I just replaced a header gasket that was only installed a couple days before but leaked, turns out the port holes were misaligned slightly causing a leak at the bottom corner of one port while all other ports lined up sufficiently well. The leaking gasket was part of a cheap gasket set and I figured it would be good enough. Nope.. it's got a Felpro on it now.

 

I'll have to take a pic of the EGR riser tube. The bottom part is attached to the exhaust manifold, no problem. It then bends and goes vertical, ending with a corrugated stretch about two inches long. Then there's another tube attached to the bottom of the EGR valve which is about four inches long. That tube inserts into the corrugated bit, underneath the toxic asbestos heat shield sleeve. It looks stock, but has no connector bits to make it solid. I think I'm going to just use it as it was considering I had no problems with it previously.

So yes on new bolts, yes on never-cease, no on the silicone goo, and get a decent gasket. I'm going to probably use this existing manifold and cross my fingers... These are stock cast iron exhaust manifolds.

I know I should wire brush the block. Should I be concerned about "junk" flying into the exhaust ports? I think wire brushing it is a good idea but I'm concerned I'll kick up some "stuff" that will fly into the combustion chamber/valve stems/etc and create a problem in the future.

...and by wire brushing I mean a wire wheel attached to a drill.

 

That statement in bold leads me to believe your EGR tube is broken. It is supposed to be one piece.

It should look like this:


NAPA used to carry them, they are made by Pollution Control Industries (PCI). You can contact them direct if you like. I think Rock Auto may carry them as well.

 

It totally looks like that, when put together. Picture the bottom bit as displayed, and the top bit with another entire 2 inches of tube stuck into the bottom bit.

I'll certainly verify this after the manifold is back on. It's possible the seam broke right at the top, but why would they have a huge chunk of tubing that is just as long as the corrugated bit stuck into the tube? I'll toss this into the order I have to make tomorrow for gaskets and bolts just to be safe.

Thanks again everyone!

 

The reason the factory never put gaskets on the exhaust manifold, was that the manifold was square and true when they put it on. BUT after mutiple heat cycle and when you un bolt it, it warps. And then you NEED a gasket, unless tou have the manifold machined down flat and true again.

I would use antiseeze on NEW manifold bolts

 

New bolts, gasket, and EGR riser tube on order from rockauto...

 

I just realized the studs on the end are not in the new bolt kit, or are they? The pictures indicate that there are no studs. Can I get these separately? They only appear to be in the pictures when you purchase a new manifold.

 

Just to update the thread, order the "bolt and stud kit" and ALSO get the studs for the manifold to downtube kit, which is Dorman part number 03135. The bolt and stud kit DOES NOT include studs for the downtube.

My weekend is booked up, but there is some possibility the truck will be running again by Monday... Here's hoping!

 

Dorman 03135 is a perfect fit for the downtube studs! The rest of this update is going on tomorrow, come heck or high water. New EGR downtube, fancy overpriced gasket and the rest. Will report back and hopefully say this project is done and dusted... Stay tuned!

 

Just reporting back. Entire problem was leaky exhaust manifold gasket. It took some bits and stress, but this "tap" problem has gone away with a new exhaust manifold gasket. Finally got that sucker off and swapped in with a new gasket, no more noise. It's simply a beauty to behold now! I've been barely unable to burn out in town after this stupid problem is solved!

 

Great news, thanks for the update!

 

The new EGR tube simply refused to thread on to the manifold, so I used the old one again. No noise, works fine. It is officially in two pieces but when the top tube is stuffed into the bottom one I'm not experiencing any leaks, as far as I can tell.

For the life of me I couldn't get the new EGR tube threaded onto the manifold bolt. It was like a scene out of "America's most obnoxious videos" or something. After two hours of trying as hard as possible I just finally said, "fark you, new EGR tube" and put the old one back on. Up and running in minutes after that.

I did have the bolt can for the inner fender liner sitting on the tailgate when I fired it up and gave it a test run. So much for those bolts, lol Inner fender liner back in sans a few bolts, quiet as a mouse and no more valve tapping nonsense.

So full solution: Bad exhaust manifold gasket. No more tapping. Up and running again and as happy as a little girl. Hopefully no more problems for a few more months. On to the next truck project, fancy new headlights!

 

Well I searched the internet as I am having this same issue. Ticking noise that sound like a valve. I did check the manifold bolts and found the rear passenger side very loose. I tightened the bolt and checked the others and still have the ticking noise..
I am thinking the gasket is blown. According to my Chiltons, this motor is the only one that requires a gasket. (94 Ford F-150 XLST 5.8 351)
Thought the least I could do is sign up and post my findings to help others searching for info.
After reading the many posts on this topic, it has definitely helped me in trying to figure out the problem.
I will post an update on my findings and the fix for future reference.
Thanks to all.

 

apparently haynes and chilton differ on this ... having looked through the haynes manual pretty carefully ( i have the same problem ) they make no mention of an exhaust manifold gasket . regardless, i WILL be using one when my time comes .

looking forward to your progress report.

 

Update!
Day 2. Hmm Superbowl Sunday, Drug TV to the garage to get to work.
Yesterday I had started to TRY to remove exhaust Manifold bolts. Heated them up with torch and sprayed them a few times and repeated this process.
My problem is I have a 94 F-150 4x4 and there just isn't enough room to get a good position with a socket on the end of a breaker bar. I managed to get a good grip on 1 and felt is was turning, but just snapped the head off the bolt
So using some football terminology, I dropped back 10, and punted by taking out the fender well. Hell yeah! Now I have great field position and should have done this from the start as I can now get a good look at everything and have pretty good access.
( Keep in mind this is a Montana/Alaska Truck and has it's fair share of rust)
I am soaking the bolts good with some Knocker Loose and will see if I can get an impact wrench in there at Half time.
At this point I have good access and if the heads snap off the bolts so be it. I can get a good grip on everything and worst case I will need to drill them out if they snap at the block.