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Dairy Mechanic
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Discussion Starter #1
Took my engine out because of oil leak and really ruff running. Took the valve covers off and the intake rocker arm bolts for the 7 and 8 cylinders were both broken on the the #7 and #8 had one backed out and the other broke. I put new injectors in, different intake and took turbo out. I'm ashamed to say that there was a socket below one off the rocker arms but not on the other. Any ideas on what could have caused this?
 

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Did you remove all the rockers to replace the injectors?
 

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If you did.. you probably did install them correctly. You probably have a few bent push rods now as well...


Pull all the glow plugs and rocker arms/push rods.
Grab a coat hanger and pick a cylinder.
Insert the coat hanger wire into the glow plug hole.
Turn engine over by hand until you reach TDC.
Install push rods/rocker arms on that cylinder.
Torque rocker bolts to 20ft lbs.

Move to the next cylinder.
 

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Kid with a Wrench
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If you did.. you probably did install them correctly. You probably have a few bent push rods now as well...


Pull all the glow plugs and rocker arms/push rods.
Grab a coat hanger and pick a cylinder.
Insert the coat hanger wire into the glow plug hole.
Turn engine over by hand until you reach TDC.
Install push rods/rocker arms on that cylinder.
Torque rocker bolts to 20ft lbs.

Move to the next cylinder.
Dirk, why is it necessary to install the rockers when you are at TDC. Shouldnt the bolts push the valve spring down? Or is this just a "better habbit"

-Matt
 

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What else?
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It's possible they weren't torqued correctly if you took them off recently.

If you've never had them off then I would say one bolt backed out breaking the other. I've seen that before on a truck with ~160k miles and the covers had never been off, though it was only one rocker.

When I put mine back on I put a small dab of blue loctite on each of the bolts and then torqued them down.

Dave
 

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Dirk, why is it necessary to install the rockers when you are at TDC. Shouldnt the bolts push the valve spring down? Or is this just a "better habbit"

-Matt

If you are at TDC, minimal pressure is on the rockers of that cylinder.
 

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Dairy Mechanic
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Discussion Starter #7
I haven't loosened those bolts, sounds like what you said that one may backed out and broke the other. I don't see any bent pushrods but I'll retorque them all and do another compression check.
 

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Kid with a Wrench
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If you are at TDC, minimal pressure is on the rockers of that cylinder.
Well, TDC on the compression stroke.

If you made sure both rockers were "loose" would probably the most ideal time to do it but I dont think that it is necessary, especially if you do like dave suggested and added some loctite.

-Matt
 

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Well, TDC on the compression stroke.

If you made sure both rockers were "loose" would probably the most ideal time to do it but I dont think that it is necessary, especially if you do like dave suggested and added some loctite.

-Matt
Weather the piston is at TDC or BDC, it doesn't make THAT big of difference on a stock valve train.
 

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And I wouldn't use loctite, but I guess you could if you wanted.
 

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It was late and I was tired last night... forgot to add this bit of info:


On a stock valve train, I've noticed that the lash is almost identical at TDC or BDC. The cam is at a different position, but it seems to not care if you are just replacing\re-torq a rocker. Why do I do it at TDC? Over the years, I've usually been replacing the springs while I'm there. Any turbo'd engine loves fresh springs. And to the OP, I would pay close attention to ALL the push rods. Do a roll test to make sure that they are good. Even the slightest bend will cause issues.







And before anyone asks, no I don't remember what the factory book procedure is. I *THINK* says to replace at BDC, but I honestly don't remember. It's been YEARS since I've seen my t444e books. But the 20ft lbs torque SHOULD be correct. :doh:
 

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Kid with a Wrench
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My book says to set the timing mark to 11 o'clock position and install both . It says they all install the same . When I did mine all the rockers were loose but two and they were not very tight just not much wiggle .
 

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Just like on most push rod Fords, the navistar 7.3 is rather forgiving when it comes to the stock valve train. As long as you torque it down properly and don't leave tools under the valve cover... you'll be fine. ;)
 
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