lifters good but my car had a lifter knock

ok i pulled my 90sc with auto apart becouse it had a lifter knock
it was consent ad would increase with rpm the rollers are round i see no flat spots from looking at them they only have slack
moving them left and right on there pin not and i cant get any of the springs to compress and the roller does seem to roller free with no weird noise so there good right ?????
ok then what it makes the sound from the time i start the car to when i kill it i can be parked and it will make the noise i pick up the car and drove it about a mile and it made the sound i think sounds like a lifter.
can it be the cam has gone flat ?
how do i tell if the cam lobe or lobes are flat can i tell if i pull the cam?
what about the valves will they couse the knocking sound
i killed my self taking that car apart for the first time and now i dont know were to go with it help

locate

the noise.. take a steel bar or wooden handle ...something you can put to your ear and long enough to reach and move about the engine.. rocker covers...exhaust manifold.intake manifold ..find where about the noise is coming from ... it's amazing what you can hear ..or you may do alot of work for nothing..I replaced 1 lifter in my first 89 xr7..#2 cyclinder exhaust
it had worn down the roller ...and poor mr push rod couldn't make up the slack ..but I knew where to look ...cause I isolated it first..but for good measure.. I layed them out on a flat surface standing up ..rollers up ...and layed a straight edge across the top of the rollers and it was easy to tell which one was gone ...and rolled the pushrods to make sure they were straight as well
....there's alot on mechanical noise under the hood ... can be hard to tell where it is coming from ...Right now my supercharge is making the sound like a lifter going .. just on idle ..It has a spring load isolator on the drive gear and the spring is weak. so it goes knock knock knock @ idle ..drives me nuts in drive threws ..hearing it bouncing off the walls ..makes it sound like a rods going ..but when I pop the belt off ..it purrs like a kitten ... best of luck .....dave

Trust me

If you had a bad roller you would know by sight, as for the cam, the only time the ROLLER cam will suffer damage is by a broke or flat roller(though I have NEVER seen a roller go flat) I have seen them break though. Either way you would definatly know by sight. if you can't find it there, and didnt have any super loose rockers I would look else where. When ever I had rod knocks on these cars it always sounded like it was coming from the upper part of the engine, after I disassembled the first one I found out why, The piston was beating off the head, seems when these lose a rod bearing they really lose it good, but oil pressure seldom fails, which makes the owner/ or mechanic think it is something else.

thanks

thanks for any help

Re: Trust me

Icemanmd said:

(though I have NEVER seen a roller go flat)

Click to expand...

Over the last five years of being a mechanical failure inspector I've seen three. All were GM. The first was a 3100, the next was a 5.7 Chevy (though this one may have had another problem-it killed multiple lobes) and just last week a 2.2 4 cylinder in a Sunfire. The first two were on 35mm but the Sunfire's is on digital. I don't have a host but I can email you the pix if you would like.

Basically, on the Sunfire (and the 3100) one lobe was heavily pitted and had a groove worn where the lifter roller rode. The lifter roller actually showed very little damage. It rolled freely and only showed one scratch around its circumference.

As for the SC at hand when a lifter taps it can be due to internal problems with the lifter OR excessive clearance in the valvetrain. A lifter requires a bit of preload to work properly. The plunger in the lifter should be up against the retaining ring when there is no load on the lifter. When you tighten down the rocker the pushrod will push the plunger down into the lifter body. The lifter's "operating range" is having the plunger down in the body from .030 to .090 inch.

Anyway, wear in the valvetrain can change the preload and cause the lifter to tap so an inspection of the valvetrain is in order. Look at the pushrod ends and you should see a shiny-smooth almost poloished looking tip. If you see deep scratches and grooves thats called scoring and means that pushrod needs to be replaced.

Next look at the rockers where the pushrod seats. You should see a shiny area where the pushrod rides but you should also see an unworn area right around the oil hole. Sorta like a bullseye. If there is no unworn area then the rocker is worn and requires replacement.

If the rockers pass tha visual then you move to the fulcrums and look for scoring and notching of the rocker body where the fulcrum rides and of the fulcrum itself. They may show a shiny area but should be smooth to the touch.

And if they pass that you look at the end where the rocker contacts the valve tip. Agains a shiny spot will be visible but it shouldn't lift a fingernail or anything. Same for the valve tip but they're usually harder than the rocker and aren't usually damaged.

HTH

Excellent post ther Parker.

very cool parker

thanks for the help parker i will check the rest of the valve train monday if you can email me the pics im going to turn the crank and see what i can with the cam in.
the 3.8 has a very open valley so i sould be able to tell if the cam is good or bad

my email corey796@hotmail.com thanks again

i wish i had read more before pulling the intake and half the engine bay apart to get the valve covers of maybe sethscope or srewdriver would have saved me alot of trouble


ps what a$$h@le designed this car i had to pull the wiper arms to pull the panel under it to pull the tube bolted to the intake i have heard storys of cars hard to work on but damn nothing under that hood is easy to get or take off