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rocker arms

1994ch

1994ch

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Ok had a bad knocking and a mac. listened to it with a scope and said he thought it was a rocker arm, front pas. side. So I have it taken apart and need to know what to look for. All the rockers wiggle slightly side to side except two. Is that a prob?? The two that don't are not next to each other. The mac. thought mabye one of the bolts were loose, what are the torc specs?? Any other ideas?

Thanks mucho.
 
I would have said vacuum pump first and had you remove the serpentine belt to check.

Since you have it down this far, there are "nylon buttons" that hold the rocker arms in place that are known to break. Since I have not been into that part of the motor, that is the best description that I can give you. Hopefully, someone with a little more experience in this area will chime in.
 
Torque on the rocker arm bolts is 40lb/ft. Try turning the engine over by hand 1/2 turn. Check the rockers for 'looseness'. Turn the engine another 1/2 turn. Check again. Do this 4 times (720 degrees). You should notice that all 8 rocker arms wiggle a small bit at some point. This is normal. As the engine cycles thru its firing order, valves are opening and closing. If you catch one just starting or just finishing, it'll be difficult to wiggle. Sounds like this is what you're seeing.

As you turn the engine over, watch the valves opening and closing. Check to see if they move the same distance. A valve that's not closing fully will hit the top of an upcoming piston and cause a knocking noise. :sad:
 
The rocker arms should wiggle around when the valves are closed and the pressure is off the arms. When the associated valve is open or partially open, the rocker arms become much more difficult to wiggle. Rotate the engine and watch the arms move. The plastic buttons are in the middle of each arm. Give them a wiggle and make sure it's not broken off. Heck, you might as well pull the rocker shafts and put new buttons in as long as you've got it that far.

As for how to tell if one is knocking, I don't know about that. I don't know as they'd knock so much as "chuff" if a valve is acting up. Any valvetrain noise I've ever heard is usually a light tapping or ticking sound. ...or the chuff chuff chuff if a valve is sticking.
 
The torque on the front one is not 10 ft/lb. Would this cause the problem? Obviously it is not right. You could disrcibe the noize as a ticking. Thanks for your help.
 
It probably would be better to decribe the sound as ticking. Only audible at idle, higher RPM's drowned it out.
 
As was mentioned, if I had it apart this much, I'd tear it all apart, inspect them all, replace those plastic buttons and re-torque everything to specs... You've already done the hard part.
 
and if just a tick, loose lines injector lines, and turbo heat shiled well know knock/tick producers on the 6.5, that sound like mechanical damage, as recommended by others, since you are in there, go ahead and freshen up the nylon buttons and check torque
 
JiFaire said:
As was mentioned, if I had it apart this much, I'd tear it all apart, inspect them all, replace those plastic buttons and re-torque everything to specs... You've already done the hard part.
Click to expand...


Sounds good. Does the push rod just lift out, basically how does it all come apart?

Still learning.
 
Iirc, you undo the bolts that hold down the shaft/rocker assembly, and lift the assembly clear. - DON'T lose the bolts!

The nylon buttons secure each rocker to the shaft in the right place... puch rods should lift straight out - can't remember if this model has specific ends, so treat them like they do.

Check all push rods for straightness and obvious wear, check rockers for obvious cup or surface wear, re-assemble in reverse order.

Somebody else chime in here if I missed anything... haven't had one of these apart for a long time, so I'm going by memory... never a good thing at my age...
 
Gold ends of the push rods go up. Most of the gold friction reducing material will be worn off by now anyway but what the heck.

Make sure the engine is not on top dead center when you re-install the rocker arms and shaft. There is a substantial chance of the lifters filling with oil when the assembly is taken apart. Re-assembly with pumped up lifters sometimes causes interference between the valves and pistons, causing damage when torqueing stuff back down. Top dead center would be with the mark pointing about 45 degrees to the right of 12o-clock. The GM manuals indicate that you should point the timing mark at the lowermost right hand (viewing from the front of the engine) water pump bolt when you are installing pushrods and rocker shafts, thus preventing any of the pistons in the engine from being at top dead center.
 
Push rods must go in in the EXACT order they were taken out...put some tape or something on each pushrod and label them 1-8, 1 being the front most 8 being the rear most.
 
ticking sound also can be a bad lifter.

If you're just going to change the buttons and retorque everything, there's no reason to even remove the pushrods. You could pull them out one at at time and roll them on a piece of glass to check for bent ones. Just be sure to get them back in the same holes they came out of and with the same side up. Whenever I pull rockers and pushrods, I stick the rockers in a box, in order, and stick the pushrods in through holes in the box lid, in order. Works great. Just label one end of the box as front, and yer in like Flynn.
 
Whenever I pull rockers and pushrods, I stick the rockers in a box, in order, and stick the pushrods in through holes in the box lid, in order.
Click to expand...

X2...
On any R&R I use the new gaskets to make a *cardboard box gasket set*. Just get some boxes, trace the gasket onto a box and punch out the holes. As you remove bolts put them into the correct hole in the box. Eliminates the WhereInTheWorldDidThisLongBoltComeFrom? syndrome. Been there - Never again.
 
I change my Buttons making sure this & that come from here & there, then I spoke to Bill Heath once and he said all i needed to do was to, pull the old ones & tap in the new with out removing the Arm , Bill, he makes it sound so easy, but if you haven`t been there before..Hmmm,, if it`s nothing more than this Okay..
 
I went a head and pulled the arms. The front spring wiggles ever so slightly and all the others are as tight as a rock. Problem?

Thanks for helping me through this as I am sailing in uncharted waters here.
 
Do you mean the valvespring is loose between it and the retainer? if so, look for a broken valve spring as they should have lots of tension on them. Sounds like you found your "ticking" as if it's loose, then it dosen't have enough pressure to "push" the rocker/push rod back to the lifter thus creating a "click" when it hits.
Don
 
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