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So I got this 1998 z28 and it always had a small ticking in it. This was in the summer. So I decided to run some sea foam through it. My oil pressure on a cold start would always go straight to 60 and then 40 once it warms up. Soon after the sea foam I noticed it started to get lower. It would cold start at 40 and stay at 20 at idle once it warms up. Didn’t think much of it. So I change the oil and I put About 4.7 quarts in it instead of the normal 6 it takes to fill it up, I was told it was 4.7, I know I should’ve checked but I trusted who told me. Anyway it ran fine. I soon later found out it took six and added to the proper level. The lifter were still quiet. I later decided to add some heavy weight oil Mobil one 15w-50. But I didn’t drive it much. Once it got cold out the lifters got super loud and almost sounds like a hard knock. My auto tech teacher says he’s sure it’s just valve train noise. The sound seems to be coming from everywhere. My friend and I took the driver side valve cover off and the cylinder one intake valve rocker arm had a lot of up and down play in it. I had videos to show. I’m just tying to figure out if it’s a rod knock, lifter, oil pump, etc
Last edited by Soap Juggernaut; Feb 15, 2020 at 03:42 PM.
Others may chime in here but I would think that for the rocker to be that loose up and down there would have to be a noticeable problem with the rocker or pushrod for either to be the cause. You could swap them with the adjacent cylinder to be sure.
If they are fine the problem would have to be the lifter or possibly the cam. Unfortunately the heads would need to come off to swap the lifter.
There may be some Magic way to get that lifter unstuck but I'm not aware of any.
Others may chime in here but I would think that for the rocker to be that loose up and down there would have to be a noticeable problem with the rocker or pushrod for either to be the cause. You could swap them with the adjacent cylinder to be sure.
If they are fine the problem would have to be the lifter or possibly the cam. Unfortunately the heads would need to come off to swap the lifter.
There may be some Magic way to get that lifter unstuck but I'm not aware of any.
thats what I expected. I listened to some other videos and it does sound like stuck lifter. I’m thinking if I change the oil back to 5w-30 it’ll fix it.
Last edited by Soap Juggernaut; Feb 13, 2020 at 11:18 AM.
I also forgot to mention that it doesn’t go away after it warms up. It’s persistent. However after about 2500 rpm it goes away. But you can hear the sound get louder if you rev it from idle to about 2400
Definitely something with the valvetrain! Put some 5w30 and throw in about a quart of Marvels Mystery oil and see if it shuts up. Certainly does not sound good at all and that rocker arm sure has some play in it. Have you checked the springs? Have you checked for excessive movement of the valve indicating worn out valve guides?
Update: I changed it to 5w-30 and the noise is definitely still there and not any noticeable amount quieter. I haven’t added any mystery oil since then but I’ll definitely try that. I didn’t check the spring or the valves either. I don’t have a spring compressor nor did my friend and even think of that. Essentially all be did was check if the rocker was loose and it was definitely not l, I checked the torque and it was at 22 ft lbs so I took it out and inspected it and the pushrod and they looked good to us so we just put it all back. Managed to smash my valve cover gasket in doing so, so that was fantastic. I took my stethoscope and it seems to be the loudest at the cylinder 1 exhaust header or at the valve cover bolt closest to cylinder 1
Last edited by Soap Juggernaut; Feb 15, 2020 at 02:27 PM.
Small update for anyone else in this predicament. Turns out it was a lifter. However it didn’t collapse and it wasn't just stuck. The roller broke off and blew the sides of it off. I will attach a picture. So my prediction is that is why my oil pressure is weird because the metal shaving got sucked into the oil pump. However I could be wrong. My other main concern would be the cam. However my teacher and inspected the lobe and it seemed fine to us. It hadn’t been driven many miles since the sound got louder so we figure it wouldn’t be bad. Hope this helped anyone in the same situation where it sounds like rod knock but has no other signs
Last edited by Soap Juggernaut; Feb 25, 2020 at 11:46 AM.
if your OP is now erratic or low you have bearing damage from the metal that went through your engine from the broken lifter
Still has OP. It has 20 lbs at idle when warm and 40 at cold start or 40 when warmed up and driving. Also I do believe that the weird OP is just the sensor because the it was only after I ran the 15w-50 through it that the OP dropped. Ever since then it had been acting weird. For the most part all my gauges are off. At least that’s what I hope. I will post another update when everything’s back together. I hope to got I’m not wrong but I am no expert just a guy who likes cars
Last edited by Soap Juggernaut; Feb 27, 2020 at 12:59 PM.
your OP #'s are good. Don't use x-50wt oil unless the motor was built with wider than stock bearing clearances
might want to look down that lifter bore while rotating the motor to see the cam lobe...if it is scored/wiped you need a new cam
Yeah I was told by a couple people to switch back to 5w-30, thought that was my issue but obviously turned out to be worse. As for the cam, we checked it over and it didn't seems to have any scoring or significant wear
Definitely drop the pan as I'm sure you have metal and inspect the screen on the pickup tube. Oil filter was the last line of defense before making its way to the oil pump. Hopefully your cam lobe was okay and you can go back together with a new lifter but after seeing that I'm thinking new lifters! Make sure the rocker arm and valve where the damage occurred is still in good working order.
Definitely drop the pan as I'm sure you have metal and inspect the screen on the pickup tube. Oil filter was the last line of defense before making its way to the oil pump. Hopefully your cam lobe was okay and you can go back together with a new lifter but after seeing that I'm thinking new lifters! Make sure the rocker arm and valve where the damage occurred is still in good working order.
yeah we dropped the pan awhile ago. Found quite a lot of metal shaving and bearings and also some lever pieces from the lifter. Pickup tube looked good. And the oil filter had some small chunks but nothing to bad. And I’m replacing the pump now anyway to a melling anyway so we didn’t even bother to inspect that. Rockers and valves looked good to us. The rocker look stock to me though so I was think that could also be a reason why the lifters failed, however I’m not sure if that could be a direct cause. If anyone knows please tell. Also the lifters looked to be some kind of cheap knock offs. I highly doubt they would be stock considering the mileage is 151,000+ and the heads has definitely been removed. I believe they are just a cheap stock ls7 set of lifters not for sure though. I do know that with the cam in the car it definitely shouldn’t of had cheap lifters. I ended up going with comp cams. No link bar at the moment but I do plan on doing so.
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Rod knock, lifter tick? 
