this can't be rite???????
Posting Guru
Joined: Dec 2009
Posts: 2,265
Likes: 2
From: Garden City, KS
Is it possible for an intake valve to be open because of the position the cam came to rest in when the motor was shut off? I'm asking more because I have no idea if things actually work this way... is this possible?
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
That is the question Chris. It sounds like he is talking about a bolt near the VC but not necessarily a VC bolt. 
There was a post about a boost leak and the fix was installing a bolt that got left out after some work. It wasn't a VC bolt and I can't find that thread.
There was a post about a boost leak and the fix was installing a bolt that got left out after some work. It wasn't a VC bolt and I can't find that thread.
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
Yep. But the cumbustion chambers should not leak into the area under the VC no matter the position of the valves. The leak should be toward the intake or the exhaust.
Posting Guru
Joined: Dec 2009
Posts: 2,265
Likes: 2
From: Garden City, KS
Right... if that was the case, then you'd be looking at a screwed valve seat, right? I hear that's pretty rare on these trucks... and now that I think of it, it wouldn't and shouldn't matter if the valve is open or not. It'd only bleed into the crank case and I guess unless he did the CCV mod, it's all one sealed volume of air, right? I'm trying to soak this all in...
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
If a valve with a bad seal were open then yes, air pressure could leak into the VC and CC. The air pressure would also pass through the doghouse and back into the intake, or in the case of a CCV Mod out that. It wou;d be so dispersed that it would probably not be heard, especially at just 20 PSI.
If the valve is closed it shouldn't allow air to get to the valve seal.
If the valve is closed it shouldn't allow air to get to the valve seal.
Posting Guru
Joined: Dec 2009
Posts: 2,265
Likes: 2
From: Garden City, KS
If a valve with a bad seal were open then yes, air pressure could leak into the VC and CC. The air pressure would also pass through the doghouse and back into the intake, or in the case of a CCV Mod out that. It wou;d be so dispersed that it would probably not be heard, especially at just 20 PSI.
If the valve is closed it shouldn't allow air to get to the valve seal.
If the valve is closed it shouldn't allow air to get to the valve seal.
Post Fiend
Joined: Sep 2003
Posts: 6,096
Likes: 27
From: Mesa AZ
Robin, if I remember correctly...that thread was about a plenum bolt that was missing. The bolt right next to the fuel gallery plug (if memory serves...)
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
A loose plenum bolt would probably allow a leak, and it might look like a "valve cover" leak to someone who isn't completely familiar with the 7.3.
It's sheet metal, it's bolted to the head, looks like a valve cover......
Pop
It's sheet metal, it's bolted to the head, looks like a valve cover......
Pop
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Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
If removing the oil filler cap does not produce a change in flow from under the valve cover, then I very strongly suspect that there is a problem at the intake plenum or possibly a crack in the charge air tube. (the big pipe that goes from the turbo to the intercooler.)
Cargo Master
Joined: Feb 2005
Posts: 2,837
Likes: 1
Guys, I think I am the one that had the bolt missing that caused the leak y'all are referring to. In my case it was the bolt in front of the driver's side intake plenum that the AIH is grounded to. When we did the AIH delete we just removed that bolt thinking that it was a blind hole, meaning that it didn't go all the way through the valve cover. I believe that in many cases this is true, but in my case it was not. I found the bolt in my toolbox and reinstalled it to seal the leak. But this doesn't sound like what the OP is dealing with.
