My 87 camaro has a 2.8L it runs fine for awhile and then the lifters pump down and oil pres. light comes on but if you cut it off and let it set for a few min. it starts up fine. If it was the oil pump it would just go out not work some of the time right ? Please help me I am normally working on my Big Block 68 (alot simpler)

 

hook it up to a mechanical gauge and see wht happens...they dont call the idiot lights for nothing...not you..the light.

 

yep, your oil pump wouldnt work intermittently.. How many miles are on it? whats the oil pressure when you first start it? is the oil level correct? Sounds like a case of excessive clearances where when the oil gets hot (thins out) the engine isnt capable of holding adaquate pressure..

 

If the lifters start to rattle AND the light shows, then it pretty much rules out the idiot light sender.
I agree with above ( worn out engine).

 

didnt see anything about rattling....

 

"lifters pumping down" was the clue

 

try this and get some real info......

The compression test, you first run all the cylinders in the normal fashion (all plugs out, coil disabled, choke and throttle held full open, crank each cylinder until max pressure reached, record each cylinder's pressure, etc.). That's the dry test. Then, you put a tablespoon or so of oil in the cylinders through the spark plug holes, turn the engine over a few times to spread it around the cylinder, and then repeat the compression test. If the rings are worn, the oil will tend to enhance the seal and raise the compression pressure significantly from the dry test. You have to do both in order for the wet test to have any meaning. If the dry test numbers are close cylinder-to-cylinder and where they should be (say 150 psi), and no significant change to the dry test, then everything's fine. If the dry test is low and the wet test is low, then you have valve sealing problems,,,
Check it out.

 

Since there's no relationship between cylinder pressure and oil pressure, what does this test show?

 

if the rings are worn , the oil will tend to enhance the seal and raise the compression pressure significantly from the dry test. You have to do both in order for the wet test to have any meaning. If the dry test numbers are close cylinder-to-cylinder and where they should be (say 150 psi), and no significant change to the dry test, then everything's fine. If the dry test is low and the wet test is low, then you have a valve sealing problem

 

Again, what does compression have to do with an oil light on and lifters rattling?
Rings have nothing to do with oil pressure and neigher do valve seals.

 

I'm leaning more toward worn rod and or main barings

 

AM Racer..I'm no GM tech or anything..this has been a hobby of mine for about 30 yrs..
I start at the top and work my way down...Heads.Rings, on a bad motor...A knocking noise would have been a better description of the sound you are hearing..WTF just through it in a dumpster and buy a v-8.:werd:

 

Thanks guys I think I will just can it and drop in a 327 my friend has laying around but i was tring to keep the 6 for fuel reasons I am spending 40 bucks a week in gas runing my Big Block 68 camaro but still worth every penny.

 

Starting from the top and working your way down is great if there's no symptoms.
When you have rattling accompanied by a warning light, it's more than a coincidence that they happened together and neither of which have any remote connection to rings or valves.

 

Admittedly, my 2.8 experience is limited. For the Camaro, getting it out of the engine compartment and later off the property. But, there was that '80 Citation that between 3 family members was still running strong with over 250k miles on it when the body fell off around it.

Now, that Citation had an aluminum body oil pump on it. I found that out one morning in January the day after it turned over 150k miles, as I backed out of the driveway to go to work. I heard a snapping sound, thought I had backed over a tree branch or something, got out and looked around, didn't see anything, got back in and took off. 3 miles later at a stop light, the lifters were rattling and it was thein I finally noticed the limp oil pressure gage.

Turns out the snapping sound was the pump idler gear shaft working its way out of the housing and getting wacked by the crank counterbalance. The replacement NAPA pump was cast iron.

Not saying your pump has broken, but the aluminum housing could be causing "issues". Sticking relief valves aren't unheard of, either (in cast iron pumps as well).