Collapsed lifters?

[Cat Fuzz]

Hi all, I have a 99 Suburban here that has some huge valve train noise. Popped off a valve cover and the rockers are all loose, some were REALLY loose. The don't appear to be collapsed, what I can see thru the little holes, that is. Are these engines known for rocker arm nuts backing off or do I have bad lifters? I'm afraid if I tighten down the rocker nuts, I might have a bunch of bent push rods when the lifters pump up again. Good oil pressure, BTW.

I would think that when the engine is at rest, the springs would push the lifter up all the way regardless of oil pressure. Am I thinking correctly here?

[maxwedge]

Is this all the valves? What seemed have brought this on? Actually at rest the valve springs on the valves that are open are trying to collapse the lifter.

[klinn]

What engine do you have? I can give you the torque specs and you could try re-torquing them. It sounds like you might have some collapsed lifters, but is there any damage to the rocker arm studs or nuts? The lifters have a spring in them, and thats where the term collapsed comes from. When the engine is off, and the internal lifter spring doesn't stay up, it is called collapsed. Now the lifters will and can drain down, but the engine typically would have to not run for along time, like a month or two. But if you are talking about a couple of hours or overnight, I think you have a problem. How many miles are on the engine?

[Cat Fuzz]

This dude brought it too me and said he had what he thought was lifter tapping. I let it sit overnight and when I started it in the morning I was somewhat shocked to hear that much racket going on. Definitely sounded like the noise was coming from under the rocker covers so I took one off to investigate. Rolled the engine around to the first cylinder that came up to TDC and it happened to be number 7 which had the loosest rockers of them all. There must have been a 1/8 or 3/16 inch of clearance between the rocker and valve stem.

Now, to confirm, when the cylinder is at TDC, both valves closed, there should be very little if no pressure on the rocker, push rod and lifter, right? If the internal lifter spring is doing it's job, its maintaining zero lash while the engine is off. So, I would think if I could visually spot the lifter tops would it be obvious if one of the lifter springs wasn't holding up?

[klinn]

Everything you stated sounds correct. The lifters are not visible, unless you take off the intake manifold. If the lifters are as bad as you say, you should be able to see some of the lifters down, but usually it will only be a hand fill, and not all of them. I replaced a set of collapsed lifters and you can visually see the gap on some of them was bigger than others, new lifters and noise was gone. If you get to that point, cut a gallon coolant jug in half and submerge the new lifters overnight in oil, this will help reduce the amount of time the new lifters will take to pump up with oil.

[Cat Fuzz]

This is what I'm trying to figure out. Whether or not I need to pull the intake I CAN see the tops of some of the lifters just not very well. I'm longing for a boroscope here.

[Cat Fuzz]

Update: I adjusted all the rockers with the engine running, like some say to do. Now, I'm assuming that since they make those little clips to deflect oil that it should have been squirting out of the tops of the pushrods at idle. It wasn't. Oil was barely drizzling out and on some no oil was coming out at all until the engine was really warmed up. Did I find my problem? Plugged up oil passages? Plugged up lifters? I'm a little rusty on my SBC internal knowledge here. Hoping a good engine flush or some MMO will get things flowing again.

[maxwedge]

Is the top of the engine visibly sludgey? High mileage, well maintained? Got good oil pressure on the gage?

[Cat Fuzz]

Has good oil pressure on the dash gauge. The lifter valley, the part I can see anyway, is a little dirty but I've seen much worse in similar vintage engines. I don't know the maintenance history. The owner just bought it a couple weeks ago used.

[aztecf]

These are famous for sticky valves, try 2 cans of Sea Foam in the gas and 1 can in the oil. I had the same problem and it was completely cured. Sea Foam is amazing

Jeff

[Cat Fuzz]

Geez, I didn't even think that the valves might be sticking.

But then again, when I ran it with the valve covers off, I didn't even need deflector clips. Oil was barely coming out of the tops of the pushrods. I mean, just oozing. Not even a hint of squirt to it.

[aztecf]

Did you try the Sea Foam?, You might just be amazed.

Jeff