I just finished swapping a '00 Camaro SS LS1 into my '92 Camaro. The donor drivetrain, as best I can tell, is nearly completely stock with the exception of underdrive balancer. The car had just over 200k miles on it. It was running and driving when I bought it. After I pulled the LS1/T56 out, it took me the right at 3 years to get it installed and running in the '92. I didn't open up the engine at all with the exception of a LS6 valley cover & intake. Got everything functional, and it started and ran fine. Another 10 months go by as I finish up other stuff, so the engine wasn't started again until this past October when the car finally was street legal.

I put 58 miles on it getting alignment and inspection etc. On the morning I decided to take it to work, I goosed it turning onto the highway (20 minutes into the trip, well warmed up), maybe 4500rpm at most. Slowing down when approaching the next set of traffic lights, I heard a very loud knocking/ticking from the engine. Dash LCD screen was flashing 7psi oil pressure. When the light turned green, I got some momentum and turned off the car to coast into a parking lot. Towed it home.

A few weekend later, I pulled the valve covers to see if there was anything obvious. The rockers were fairly tight (wiggling them side to side), so I don't think it's a bent pushrod. Springs all appeared not broken as best I could see. Oil up top looked clean. Spark plugs were undamaged and the engine turned over easily by hand. I looked up how to determine where a knock was coming from, and of course the car is test while running. I hate the thought of possibly causing more damage to diagnose an issue, but buttoned it all back up anyways.

It started right up, low oil pressure for the first second or so, then stabilized around 40psi. What shocked me was the noise is now gone. What on earth would make such a racket and then fix itself? The only thing I can think of is maybe a lifter collapsed when I rev'd the engine? Would a lifter cause low oil pressure when it collapses?

I've started the car a few mores times with the same thing happening. I've got the gauge cluster displaying the oil pressure during start up. Initial start up it's a second or so before reading 40psi. No bad noises when rev'ing the engine with no load.

Today I removed the oil filter and cut it open. Some dark sludge-ish stuff in the pleats, and 3-4 very small shiny metallic (non-magnetic) bits I found, but not any significant amount (in my opinion) that could indicate it was a bearing. Granted it didn't run long after when it first started making noise, but still a good 30 seconds. I'm really hesitant to drive it in case I damage the block or crank. I will eventually rebuild it with a cam and heads etc, but not until I save up for it.

 

I'm guessing the oil pump sucked some air when you goosed it. It might have been a little low on oil and uncovered the pickup at some point. Upon restart, after a bit it recovered. Run an extra quart of oil and see if it still does it.

 

It's possible that the oil pressure relief was stuck open and then started working again.

 

That IS possible, which would warrant taking the pump out and cleaning/deburring the passages, OR just putting a new pump in.

 

I've had similar things like this happen. Every time it was piece of carbon that came off and of course until it gets mashed and spit out the exhaust it knocks like hell. I had a TA at a body shop for major work after hitting a deer. Car ran fine quiet etc when I dropped it off. 2 weeks later I come pick it and it knocks badly.....of course no one knows nothing. I warned the owner I didn't want anyone driving the car and recorded the mileage but they must have pulled the fuse. Insurance company got involved because NOWAY I'm taking a screwing from some idiot driving the car. Long story short from them running the **** outta it carbon had broken off and was hammering in a cylinder. Unfortunately for me it damaged something because the engine had a slight knock after that and quite a while later a piston failed.

Another possibility is a stuck valve.

If its quiet now I won't worry about it.

 

What does any of that have to do with no oil pressure?

 

Who knows? Sounds like another one of his piston slap episodes...

 

ABSOLUTELY NOTHING! LOL I was only addressing the noise, happens all dee time.

 

Lack of oil pressure tends to do that!

 

Yeah, the noise usually quits after a while, for one reason or another. The last noises are usually MUCH louder....

 

Thanks, that makes much more sense. I was thinking a failed xyz caused the noise and the low oil pressure. Never thought about low oil pressure causing xyz to not function correctly and cause the noise. I was running 6qts, although with a aftermarket dipstick. I'll throw in the factory one again and make sure it's calibrated right.

Kinda kicking myself for not changing the oil pump when it was out. I was afraid it would turn into the "while you're here" snowball and be replacing timing chain, gaskets and more. I'll run it *gently* until I get around to putting in a new pump. I know it can be done in the car in a 4th gen, I'll need to see if I have room in my 3rd gen.

I'm familiar with the "last noises" unfortunately.
Bought Knocker,'86 Camaro in Amarillo and drove it back to College Station. ADDED 8qts of oil to get it home. Was knocking badly when I pulled into the driveway. Replaced with a mild carbed 350.
350 replaced with 305 TPI to go racing. Then replaced with an LT1. LT1 lasted 2 seasons or so before punching a hole in the side of the block. To be fair, it did give me some warning but I ignored it thinking it was something else.
Shortly after a rebuild with another bottom end, oil pump drive gear stripped in the new engine. Only really heard the clatter after I pulled off track. Bearings, cam and lifters needed replaced. Stupid me didn't know about the issues with the high volume pumps.

 

LOL grandpa is on the sauce again.



One thing that came to mind while reading your thread.. If the motor sat for years with pressure on the valve springs and lifters there's a good chance they're weak. I would plan on changing them soon. There's a lot of threads where guys get upper RPM cut out and have motors that have been sitting a lot. It's most common on low mileage motors. Nearly 20 year old motors with 50k or so on them have done a lot of sitting most likely.

The noise could be anything, when something has sat for years weird **** happens. Keep an eye on the gauges and an ear on the engine and run it for a while and see how it acts. The drop in oil pressure is concerning and the drop in oil pressure would cause noises. The oil pump may have cavitated for a minute, the pick up tube o ring may be shot and getting some oil back on it may have brought it back a bit. I'd also consider changing that o ring asap.

I hate to say it but there's a few things that would have been a great idea to replace with the motor out like the barbell o rings, pick up tube o ring, lifters and springs..

If you stored it with the rockers pulled off like you should have then the lifters and springs are likely okay, but okay at best.

 

One of my lifters wasnt happy when I did my cam/spring swap. I left the heads on so stock 88k miles rockers, I didnt touch the oil pump either. First start up it was a heck of a noise, had good oil psi though. I shut it off, said WTF did I do wrong??? Started it back up and it was there, shut it off again and let it sit and restarted and it was gone. First test drive it came and went twice, hot and cold. After that day its never done it again. It was like a an air pump with a leak type of ticking. Im just glad it went away, probably a lifter that just lost all its oil and was dry.