03 HELP! headstuds+new gasket =bent push tubes
 

heres the backround 03 6.0 90k, sct tuning, exhuast, egr delete. lifted a head after sct was installed. had the heads checked, machined flat and new valve seals installed by a machine shop, installed arp head stud, oem head gaskets and put truck back together. upon start up truck had low power, valve train code for #5 cylinder and a hard miss( sounded like a train). pulled the pass. side back apart #5 push tube was bent. installed a new one, bumped truck over with starter and no fuel and bent #5 again before the truck even had a chance to fire.

checked the valves were opening and reinstalled another push rod this time making sure it was seated and not on the lip of the lifter, turned the truck over by hand many times, reassembled and # 5 cylinder is now fine.

truck still missed and has a #4 cylinder valvetrain code, both have been exhaust side. the driver side initially was fine and only a #5 code was causing the miss. now that the # 5 is alright the # 4 push tube has bent.

need some help on this one. other then checking to make sure every push tube is seated perfectly, what else can cause this? my thoughts:
1. lifter wont calapse
2. the machine shop milled greater then .008 off ( although this would cause all the tubes to be too long and bend)
3. ?????

NEED SOME EXPERT INSIGHT

thanks in advance sorry for the long post.

-Chris-

Would really like to know how much they machined off and what they did to counter act the new thickness? Ford's spec for thickness for the heads is a MIN thickness of 3.74". Did they do a valve job? As in re-seat the valves? That usually will let the valves sink into the head a little after the head surface is machined flat. They should also be trimming a little off of the valve stem to make sure the valve springs don't bind. I'm curious to know what they took off. There is VERY little clearance as they sit from Ford, which is why Ford recommends no machining. We still machine anyways, since new heads come in out of flatness spec, so it's not impossible, but you can only take off a tiny amount as I'm sure you know.

I've also seen some heads go back on where the rocker arm isn't seated correctly and cause similar issues. Can be hard to catch sometimes with all that going on, but if you turned over by hand first, I don't know how it would have done this. My guess is they machine shop might have taken too much off.

I'm no expert, but the last time I saw a post about bent push rods post HG change, it was because the pushrod wasn't in the lifter cup. That was enough space to bind the pushrod.

If they only machined for flatness then the machine shop screwed up, with the 6.0 heads if you take off .0150 for flatness the valves have to be sunk .0150 and also the springs would have to be shimmed the same amount or have that amount removed from the tip as stated before. If this procedure wasn't done then that is your problem, the machine cost should have been around $700 if it was done proper, might very a little depending on location. Most of the time a bent pushrod is caused from not having them seated properly during install, always push on them with your finger to feel them spring back, if they don't feel like they are on a spring then they are not seated, the lifter will feel springy.

Most say not to go over .007" anyways with these heads, but again that's just a number pulled out of someone's arse, since the real spec is the min thickness on the head. You're right though Bob, when it gets up there in material removed, those steps should be taken.

I was just throwing out a number for reference, no idea what the real spec is.

Gotcha. No spec for what is allowable to mill off, the real spec is a min thickness on the head. Head should be no less than 3.74". :c:

we figured it was the push rods sitting on the lifter lips possibly due to the headgasket holes not being exactly in line. the number 5 cylinder is fine now after two bent rods and finally turning over the engine manually to make sure nothing is binding. what i cant figure out is the driver side never had a code thrown for power balance/ injector/ valvetrain for # 4 cylinder until number 5 was corrected, unless it was bent and no code.

thanks again for the replies guys still trying to figure this one out. I was surprised to see the valvetrain set up, the valve springs sit really close to eachother and even closer to those expensive injectors!!!

I'm pretty sure HG hole alignment was the cause in the other case where the push rods weren't seated in the lifters.

Hmmm, interesting.

What size dowel heads do you have 96 black cloud? I'm assuming the corresponding gaskets were used for the right heads right?