I want to make 100% sure the noise I'm hearing is indeed a collapsed compensator.
Here's a video:
When I pulled the valve cover last time and rotated the engine, every compensator "collapsed" as the corresponding lobe pushed down on the arm, but returned as the lobe came back up.
I'm definitely sure this is a valvetrain issue, as the noise reverberates for a second, unlike a knock, due to the valve spring vibrating as it is "shocked". Plus, I don't think you hear of many bottom end issues with these engines.
From my understanding, a worn lobe would be very obvious with score marks. While they don't have a mirror finish as they did before my top end work, they're still perfectly smooth. No obvious wear marks.
I hear of people changing out the shim or "button" that the rocker arm rides on to take up extra space. I thought that was the compensators job...
A loose valve guide wouldn't produce this kind of noise, right?
A good rule of thumb is that top end noise usually occurs at 1/2 engine speed, bottom end noise at 1/1 of engine speed. Thus at 600 rpm, if you are hearing about 5 ticks/second it is almost certain that it is coming from the valve train. The noise indeed sounds to me like it is rocker arm/cam related. Compensator noise usually comes and goes as it "pumps up" and then loses pressure again, so it it is a constant cycle of tapping, then no tapping, then tapping again. Loose valve guide by itself should not make noise, but will lead to issues on the compensator and related components such as the rocker arm. Methinks some top end work is in your future...
Would you advise against running the engine with the valve cover off? I would make some sort of a contraption to catch the lost oil so I wouldn't make a mess. It's just so hard to hear exactly which one it's coming from, and my pockets aren't deep enough to replace everything.
Should I just start pulling springs and checking valve guides for play? The head doesn't have to come off for guide replacement right? Or do they have to be pressed in and out?
Unfortunately for guides yes the heads must come off. You can run without valve covers but it's messy and down right dangerous for obvious reasons. Before you do that I would try and wiggle each rocker arm by hand. If you find one has a lot more movement than the rest that could be the problem area. They are supposed to be tight under valve spring pressure and hydro pressure from the compensator. If not conclusive then pull all rockers and remember to "tag and bag" to make sure you keep them in order so they go back in place. You might get lucky and then see a failed compensator by a "popped collar". Also less likely is busted valve spring so inspect them all visually. This too is an easy fix.
Here is a pic of what I mean by "popped collar". In this case the valve guide is worn thus the valve had a lot of movement within the guide, aggravating the rocker arm and compensator in the process:
Nope there is nothing to be gained by fiddling with the compensators. Replace suspect ones and that's it. The lateral motion makes the ball unit break loose of the collar. That is my theory only.
Rocker arm must be tight under all conditions as it should be under constant load from the spring and pre load is maintained by way of the "thrust piece".
One last question, do you know how exactly the compensators fail? I assume not much differently than compensators in other cars. Sludge and grime starts to build up and regulates movement of the piston, correct?
I am not 100% sure why they go tits up, but it you remove all the rockers you will normally see a lot of sludge in the gallery which gets trapped and really has no way to get out of there other than tedious manual clean up. You can try engine flushes and such but if the sludge up there is bad you have to dig it out by hand. Oodles of fun...
I had the heads off a few months ago. I completely stripped them, except for the compensators. I'm guessing debris got into an oil galley and clogged it up. There was no sludge in the galleys when I was finished with them.
I'll try a skinny pipe cleaner-type brush in the oil ports under the compensators and see if I have any luck.
It was dumb of me not to remove the compensators when the head was off. Very dumb.
be sure to torque them down to spec. On my parts car the PO had new cams, rockers and compensators. When I pulled the heads the one cam lobe worn flat and the rocker that was virtually non existent had a curious ability to be removed by my thumb and forefinger. Every other one was quite tight. When I replaced my lifters I found my driver to have some that were loose as well but just tight enough to require a tool to loosen. Follow the FSM specs with a good torque wrench.
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