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Ted G.
Ted G., ASE Certified Technician
Category: Chevy
Satisfied Customers: 6117
Experience:  20 years auto repair experience, ASE Master Tech, Mechanical Failure consultant, Expert Witness
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How do you check for a collapsed lifter on a big block chevy

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how do you check for a collapsed lifter on a big block chevy
Take a hammer handle and press down on the pushrod end of the rocker arm and if the noise stops, that lifter is collapsed.
Customer: replied 7 years ago.
Opps, I had already tried that but will do it again to be sure....................
Customer: replied 7 years ago.
could not push down any of the lifter rods, some of the rockers are slightly loose when engine is off. The clicking noise does not seem to be coming from the rockers themselves, it seems to coming from the cam end or the lifters. I have cut open an old valve cover so that I can watch the rockers and the oil supply to the rockers while running the engine. The engine is quiet when cold or has cooled off some, the noise starts after I run it at road speeds for a short distance or run up the engine while sitting and gets warmed up.

Could it be something besides the lifters?
No, as long as they are not losing oil pressure then it is likely the lifters. If they have some miles on them they may have worn some clearance in there and drop pressure when the oil thins out after it heats up.
Customer: replied 7 years ago.
the engine is a relatively new Jasper replacement engine with mayby 3k miles on it, although it is several years old now. During my last test pushing on the rods it seemed like the noise got louder. I also noticed that the oil pressure has dropped to about 20psi while at idle (it had been around 35psi eariler) . The oil pressure was also not increasing above 40psi when i revved the engine either. So now that it is hotter it is not as high.

If a lifter is collapsed will it still push the valves? As stated at the beginning they all seem to be moving the same and the engine is not missing. I'm confused and fustrated with this problem....
Yes, it will push the valve but the pressure of the spring makes the lifter push down too far and tat causes clearance when the spring unloads, so you here the clack as the rocker loses and then regains contact with the valve end. I am assuming you do not have adjustable rocker arms, is that correct?
Customer: replied 7 years ago.
hello Ted, are we still connected?
Customer: replied 7 years ago.
I tried 3 times to continue dialogue with Ted and could not make contact.
My last responses included the following information: I do have adjustable rockers and I tried adjusting them this morning. I tightened each valve rocker by 1/4 turn (one at a time) to see if there was any change in the noise level. It did not seem to make a difference.
I did notice that my oil pressure level had dropped down to under 20psi at idle when warmed up, it had been higher than that yesterday. The oil pressure was near 60psi when first started but did not hold there for long. It would not even get to 40psi when engine was revved after it had warmed up.
Could I have an oil pump problem? I had been told that chevy oil pumps rarely go bad, or could it be another problem in the sump?

Sorry, for some reason it did not come through. If the oil pressure was close to 20 at idle it should not cause the lifters to make noise. First thing you need to do is baseline the lifter's adjustment. You need adjust the rocker with the lifter on the base lobe ( I can post complete directions if need be) and then adjust for zero lash plus 3/4 turn. You can feel zero lash by spinning the pushrod and as soon as it gets drag on it that is zero, then turn it 3/4 turn tighter. If it still makes noise with the lifters adjusted like that you likely have a failure/collapse.
Customer: replied 7 years ago.
It would be a great help if you could post the adjustment process. How do I get each lifter on the base lobe?

I am still bothered by the fact that my oil pressure is erratic. The oil pump gauge is driven by an oil line from the engine, its not electric.
It will show up as more erratic on a mechanical guage, but if you are over 15 psi with a standard pump you should be okay.

To adjust the valves:

Rotate the engine to TDC on #1 cylinder, put your finger over the open spark plug hole and it should blow out as you approach TDC. Now you can adjust the following valves:
Intake 1,2,5,7 Exhaust 1,3,4,8

Now turn the crank one full turn to TDC on cylinder 6. You can adjust the following:

Intake 3,4,6,8 Exhaust 2,5,6,7

Ideally when that is done they will all be quiet, if not you may have to adjust with it running.
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