halltrash
New member
i would want to puke good luck
Upcoming Head Gasket replacement
- Thread starter kleake
- Start date
Weird stuff. Sounds like whoever did the remanning of the heads didn't stay within specs. The best solution would be to get shorter pushrods, I'm not sure I would grind the bridges for fear of them being weakened and failing at some point.
kleake
Member
Spoke with 2 shops and 2 machine shops. None have seen this issue, but all seem to agree it's likely the heads were not machined correctly and the valve stem height it too high. "IF" this is the case, Ford only covers up to $150 of labor. hahahaha Yea, that was my thought too. I am going to pull a valve spring tonight and measure the valve stem height to verify, but I can't find the specs anywhere. Does anyone know the specs of what they should be? Also, if that is the case, all agree that taking a little off the tops of the bridges should be an easy solution rather than pulling the heads. If I can get that spec, and if I can get a valve spring off with my compressor i'll know for sure.
Valve height measurement isn't really going to tell you much, you'd have to know the valve seat depth and head thickness also. Here's some info:
http://southeastcylinderhead.com/resurfacing-ford-6-0-6-4-liter-diesel-cylinder-heads/
http://southeastcylinderhead.com/resurfacing-ford-6-0-6-4-liter-diesel-cylinder-heads/
kleake
Member
That is one I found when I was searching as well. You are correct when making that statement although, what I am after is to find out if these are 100% stock tip height valves that never had anything taken off of them. If they are, then the issue is that they never removed any material to compensate for what they took off the heads. OR if I know the tolerances, then I should be able to at least tell what is going on. For example, if there is a range of .050 that the lifter can adjust for, but they only took off .005 from the heads, then there shouldn't be an issue. BUT, if the valve stem height should be say 2.0 inches, and it is 2.060, then I am .060 too tall and it's beyond what the lifter can accept. If this is the case, that means they ground the valves too deep into the heads. If these valves come out right where they should be, then it would point more towards the rockers.
I guess at this point i'm kinda digging to try and find a way to determine which component is at fault so I know if I need to simply machine my bridges to make up the difference, or if I need to go back to Ford for a new set of rockers.
I guess at this point i'm kinda digging to try and find a way to determine which component is at fault so I know if I need to simply machine my bridges to make up the difference, or if I need to go back to Ford for a new set of rockers.
Great link, thanks.
Sorry for your troubles, kleake. I hate the 'QC' that is around this day in age.
The problem with measuring valve stem height above the head to find that out is that it won't tell you. You don't know the thickness of the head or valve seat depth to know where the other end is. Switch the rockers around to see if the problem moves, I'm willing to bet that it doesn't. I'd be weary of cutting the bridges, that's a high stress part. I can't imagine it would cost much to have a machinist turn a few of pushrods and take some material off. You won't have any idea if all the measurements/geometry are correct but at least it will work to get the truck running. The only way to know where everything is would be to pull the heads back off, and I know for me that wouldn't be an option.
kleake
Member
I partially agree. If they did things right, the valve stem should be lower than factory. If it is equal or higher, then that would explain why they won't close. I know these heads have had material taken off the surface, I just don't know how much. Basically if they take .005 off the surface, the valve tip should be 1.5 times lower to compensate so approximately .0075 lower than stock. In theory, the lifter should be able to compensate for small amounts though.
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kleake
Member
Well, my valve spring compressor will not work on these springs so I can't find valve stem height. What I did do is put 4 layers of tin foil, .003 to be exact, under the rocker and that was enough to seal it up. So, if the rockers have a 1.5 ratio, I should be able to take .005 off the bridge and be ok, but i'm thinking to have at least a little clearance and not burn a seat, that .010 or even .020 would be best and that would give me around .010 or more for the lifter to absorb. Just by pushing those down it feels like they have around 1/4" of travel so that should be fine. Heck, I could probably polish off .003 myself with a buffing wheel!
kleake
Member
I measured all of my bridges and they vary by about .005 across all of them. So, I moved my thinnest ones to a bad cyl and all was good torqued down. That is my solution...... That small of a difference is enough.
kleake
Member
Decided to go ahead and remove about .015-.020 from each of the bridges. So far I've got the passenger side all pushing 360-370psi. My gauge pegs at 375 on the 5th turn on each of those cylinders. Here is what it looks like.
Before:
After:
Before:
After:
Last edited:
kleake
Member
Ok machinists, I picked up a different valve spring compressor and got an accurate valve stem height. They look to be within spec, however there is a little shim/rotator at the bottom of the spring. I couldn't get it out of the head but spec shows 2.300-2.320 and I was getting 2.310-2.315 with this cup in. The question though, are these supposed to be measured with these in place or directly on the casting? Everywhere i'm reading says directly on the casting but that is just standard heads, not the 6.4 specifically. If it's supposed to be casting, that would explain this big time! If it's from the top of that rotator, then they are within spec, still raising questions. I'm still machining the top of my bridges, but at least I will feel more comfortable knowing for sure.
webb06
Active member
Ok machinists, I picked up a different valve spring compressor and got an accurate valve stem height. They look to be within spec, however there is a little shim/rotator at the bottom of the spring. I couldn't get it out of the head but spec shows 2.300-2.320 and I was getting 2.310-2.315 with this cup in. The question though, are these supposed to be measured with these in place or directly on the casting? Everywhere i'm reading says directly on the casting but that is just standard heads, not the 6.4 specifically. If it's supposed to be casting, that would explain this big time! If it's from the top of that rotator, then they are within spec, still raising questions. I'm still machining the top of my bridges, but at least I will feel more comfortable knowing for sure.
The little shim you're referring to is part of the valve seal if I'm seeing it correctly.
Glad to see you're actually trying to find a solution. Most people would be pulling their hair out by now.
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kleake
Member
Haha, I'm about to pull my hair out anyway! Lol
Is that is the valve stem seal, that would mean that the stem height was set after the seals were installed and would definitely explain why I'm having this issue.
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Is that is the valve stem seal, that would mean that the stem height was set after the seals were installed and would definitely explain why I'm having this issue.
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Wizbangdoodle
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I'm having a hard time understanding how that "shim" would cause a valve to stay open.
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kleake
Member
Valve stem height is supposed to be set from spring seat surface on the casting, to the tip of the valve stem. If it was set after the seal was installed, the stem height would be the thickness of that seal too high. If the stem is too tall, the lifter can't take up that much slack and bottoms out, holding the valve open.
Per factory spec, the stem height should be 2.300-2.320. Say the seal is .250 thick (guessing) then the stem height would be around 2.550.
I hope that makes sense, I'm pretty confused myself on this mess.
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Per factory spec, the stem height should be 2.300-2.320. Say the seal is .250 thick (guessing) then the stem height would be around 2.550.
I hope that makes sense, I'm pretty confused myself on this mess.
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kleake
Member
Possibly, but we are talking about stem height which everything I have heard is that it's measured from the casting without any shims. The 6.4 might be different since the stem seal is designed different. Wish I had access to that specific spec.
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Typically you put a test spring in that seats the valve fully in the head, but doesnt have 100# of pressure, that is typically measured with the valve seal installed, so the valve isnt flopping around, and will give you a solid repeatable reading. There is some play in valve guides, but the seal should keep it centered. At least if i remember the engine building classes ive taken correctly LOL. Anyways, i still think its an issue with your rockers, especially since you said it followed the rockers. Did you make sure the rocker spacer that bolts to the head was fully seated? It has dowels in it that can bind, and cause goofy chit too.
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