I used a block tester on it a few months back and it passed, so I don't think it's the HG. Plus, that is on a different layer of the sandwich, so to speak. The air is pushing out the throttle body which is sitting on top of the intake manifold. The cylinders should pressurize individually, so if I had a bad valve or two, it would affect those cylinders, not all cylinders. All rockers are out, so nothing is holding the valves open and the cams mean nothing at the moment. Maybe there is something I'm not understanding?

 

If the rockers are out, and the valves still aren't sealing, you have an issue. That is the only way for air to get to the throttle body, and if it is leaking out that fast, then there is a serious problem. You need to pull that head, and see what's going on.

 

I'm not suggesting that the head gasket is bad at all. I'm suggesting that you may have some problems with the valves - burnt, for example. At the least, something may not be seating correctly.

 

I've come to the conclusion that the only possible reason for air rushing out to the manifold, would be intake valves not seated properly for whatever reason.

I'm hoping that the manual manipulation of the valves, springs and seals may have things out of line right now and when I put it back together and start it, hopefully everything will vibrate back into line. I've noticed that the cylinders in this bank are angled much steeper than the other side. I could tell because when I put a screwdriver through the spark plug hole as I turned the motor (trying to watch it rise, to get TDC on each piston), the piston would lock onto the screwdriver due to the extreme angle and I would have to back off and try again. So this angle and me tapping on the valve stem seals with a deep socket, compressing springs and them not being perfectly centered, etc. All I can do is hope. The motor was running like a sewing machine before all this, so I'm hoping there are no issues on the underside of the head. I would HATE to have to pull it.

 

The pistons should be the same on both sides... Refer back to the 4.7 teardown thread.

I sure hope what you are describing isn't bent valves or dropped valve seats....

 

Quoting myself here. My suspicions have been bolstered and likely confirmed.

Today, I aired up a cylinder, placed a block of wood of top the intake valve spring and tapped it with a steel hammer. The change was not what I was expecting, but it confirmed my initial suspicion. When I tapped it, air began gushing right past the valve itself. I removed the spring and hooked it back up again and it sealed. So that's telling me that there is a small bit of play in the valves that can cause them to not be perfectly aligned when manipulated. It could be that the spring is off center or whatever, after manually compressing it. So I believe I just need to run the motor and hopefully things will vibrate into place.

Just in case there is carbon buildup affecting things, I'm also going to run a can of CRC intake valve cleaner through it, right before I change the oil. I'll also run a compression test after I drive it for a while. I say all this, with the hope that it even freakin starts, after all this work.

I'm almost done putting it all back together. The valve covers are back on and I'm hooking back up all the knick knacks. Should be done by tomorrow. I'm going to crank it with fuel pump relay removed for a while, to get oil up in the top end before starting.

I do appreciate the help fellas.

 

Well, I got it all buttoned up this evening and when I started it up, it ran like absolute crap, for the first few minutes... knocking sounds and all. I thought all was lost, then it smoothed out and began to run like the truck I knew. I guess the new hydraulic lifters took a while to prime and maybe the valves are seating a bit better now. Tomorrow I'm going to spray a can of CRC GDI Intake valve & turbo cleaner into the intake, run some motor flush through it, then change the oil.

This work fixes multiple issues and hopefully brings the truck near perfect....

The new lifters and springs fixes the rocker ejection. Hopefully mileage increases.

New valve cover gaskets takes care of the valve cover leak. No more oil loss.

New valve stem seals fixes the occasional puff of smoke when accelerating from standstill.

Sure is nice to hear no clattering on cold starts!

 

Completed all this today. Ran the CRC through the brake booster vacuum hose. After the oil change, I went for a half hour drive on the highway with O/D off, so the higher RPM would blow out any crud on the valves. I reused the motor flush from the truck in a Hyundai, right before I changed the oil in that.

Did I mention that I love the quiet cold starts with no lifter clatter. This completes the fix and the truck is running really well. The beast is back and ready for another 100K!

Thanks, all.

 

Thanks for the update. Glad she's running like new!

 

Magnet, I've always meant to ask what you meant by this. Why would the exhaust rocker have been worse? Would it have damaged the cylinder with no way for the gases to escape?

Thx, Dan!