This is my first Ford so any insight would be appreciated please. I just bought this with the 5.4l and only 80k miles. I'll skip the boring stuff.

When I checked all the normal leaks, none was to be found. I finally got under the truck when it was running and noticed I had coolant spitting out of the exhaust manifold at #4 cylinder. There just happens to be a broken stud and small exhaust leak(never thought I'd be glad to have an exhaust leak lol). So obviously I've got coolant going through that cylinder and decided to dig into it.

After I got the intake off, I looked at the runners on the head and noticed the #4 runner was a bright silver in the corner next to the water jacket in the block. All the other runners looked normal. Because of this I figured it must be the intake gasket leaking. Because of that, like an idiot I never went any further and did a compression test. I just ordered a new gasket, plugs, cops. I didn't notice any cracks or anything wrong with the intake so I put it back together. I used the expensive steel gasket from felpro and followed Ford specs for torque and sequence. It was good for a few days but has started to leak again, but it seems less this time. Only afterwards did I read about checking the intake mounting surface with a straight edge

This is what I've noticed so far. If I start it and let it sit and idle, it will continue to smoke out the tailpipe. Not a lot though. If I start it, let it run for a few minutes then go for a drive, it will only smoke for about a half mile then it will clear up and won't smoke again all day. It's clear when I restart or sit at idle. There is no coolant in oil. I did a combustion gas in coolant test which came out negative. I haven't seen any bubbles in the coolant when running, but after it cools and I take the cap off, lots of pressure will vent and the coolant level in the tank will rise a few inches. There is no overhearing issues at all. I haven't had a chance to pull it in and do a compression test yet.

Is it possible that I blew an intake again? Is it possible that after it heats up that something expands and seals up? Just doesn't seem like a head gasket too me but I know nothing about these motors.

 

Btw, this is in an 03 f350. Also there is no hesitations or loss of power. Seems to idle and run very well. I do throw a p1131 code occasionally. I'm guessing the antifreeze in the exhaust junked the upstream o2 sensor.

 

Metal expands as it gets hot. This does not sound like an intake issue to me. Sounds like you have either a blown head gasket which is my first bet and your best bet. Other being you have a cracked head.
did you do a compression test? Can you do a leak down test? If not if you have an air compressor you can pump air into the cylinders on that side and look for bubbles in the radiator(if possible) or overflow, listen for air coming from the exhaust leak, and listen for air escaping thru a connecting cylinder. Do this with all plugs removed from that side and engine cold. If any of these leaks are found, you likely have a blown head gasket

 

Plan to do a compression test in ther next few days once when I get this other rig out of the garage. Never done a leak down test, I'll have to see if I can borrow a tester. One question i have on compression test is if let's say number 4 is low, how do you tell if it's the head gasket and not leaking out the intake valve and through the intake gasket? Are the valves supposed to be closed all the time? Feels like a stupid question but all I've ever worked on are pushrod engines. Thanks for the response

 

if compression is lower on 1 cylinder than the rest, add a couple drops of oil to that cylinder and recheck compression. Adding oil will seal any gaps in the piston rings allowing the compression to raise higher. This would mean new piston rings.
it this does nothing and you have an air compressor, pump air into that cylinder and listen for air escaping into the intake or out through your exhaust, like from the exhaust leak you have.
air escaping through either places means you need to have your heads done. I wouldn't do just one if you have to do this. Do both.
I could have this wrong.