89 olds 307 developed lifter tap, low oil pres

My 89 caprice wagon with the olds 307 vin Y engine with 93k recently developed what sounds like no oil is getting to the lifters. I recently changed timing chain and water pump and put together without cam button and spring. developed the noise the next day. i drove the car around for a day with the clacking, hope i did not damage it.
I then reinstalled the cam buttom but it did not help the problem.
I then installed a manual oil pressure gauge and ran the motor
30 psi at 2000 rpm but then it dropped off to 18 - 20 psi
at idle was 10 psi but then started to fluctuate around 7 - 10 psi
I dropped the oil pan and it was totally clean, cut open oil filter, totally clean, took apart oil pump, seemed good.
I took off left side valve cover and spun pump with a drill, got the same pressure readings spinning pump with drill. 5 out of 8 rockers were getting oil yet there still seems to be a restriction someplace.
Has anyone heard of a similar problem with this engine?
Any suggestions would be appreciated.

I had the same problem, turns out I had a collapsed lifter. I found that out during dismanlting the engine for a rebuild. Can you pinpoint it to a single rocker. Try a valve adjustmet, it acted as a temporary fix to my knock. Each rocker when in the relaxed position shoild have just enough play to spin the push rod. If the pushrod can be moved up and down, even a little bit, its out of adjustment. Mone was so bad, the rocker felt as if it was practically ready to fall out of the engine.

Thanks for the reply, this is a roller motor and has no way to adjust valves at rocker arms.
I still suspect a blockage in the oiling system, question is where?

would a collapsed lifter cause low oil pressure?

No, but low oil pressure will certainly cause collapsed lifters. It is difficult to determine what is causing an oil pressure loss without disassembling the engine. If the oil pressure loss was due to a lifter, that oil pressure has to go somewhere, and in this case that would be up the pushrod to the cylinder heads. If you see a LOT of oil flow up there with a valve cover off and the engine running, this is a possibility. My personal guess would be a main bearing, especially if you can hear a 'thud' from the bottom end of the engine while it's under load.

I did not hear any thud or knock.
it sounded like clacking lifters.
also, oil pressure builds to 30psi then drops off to 18 - 20psi while rotating with a drill motor.
my next step will be to remove the intake to inspect further, then maybe removing cam if the main bearings are ok.

Thanks for your help

I did not hear any thud or knock.
it sounded like clacking lifters.
also, oil pressure builds to 30psi then drops off to 18 - 20psi while rotating with a drill motor.
my next step will be to remove the intake to inspect further, then maybe removing cam if the main bearings are ok.

Thanks for your help

Main bearings require removing the engine from the car as these are what the crank sets in.

Quote: My personal guess would be a main bearing, especially if you can hear a 'thud' from the bottom end of the engine while it's under load.

In my '89 GMC w/ 112k, when I put it in gear, and whenever the engine is under even a slight load I get a sever rattling that sounds as if its originating from the bottom of the engine. When cold I get 30+ PSI, when warm its only 10+ PSI... Thats a bad thing right?

Bearing wear, either or both mains and rods, will manifest as a 'rattle-knock' when the engine is first fired after sitting for several hours. This sound is hard to explain, it almost sounds like it's going to blow up shortly after it fires. If you have this, along with low oil pressure, it might be a good time to think about a rebuilt engine. 10psi is never good for any engine, methinks.

--

In late-'87, early '88, I had a 1972 Impala Custom coupe that had been rode hard and put away wet, and the engine was pretty much 10-7. It had oil pressure, but it also had 3 wiped cam lobes and two blown head gaskets (out of 2 total LOL), along with copious amounts of cylinder head wear. Throw in a little piston wear, and this thing got 15MPG on the highway, on BOTH gas and OIL. Yes, that's 15 miles per GALLON! The car was a smokescreen that would have made James Bond proud, and lots of liquid oil shot out the tailpipe along with the smoke.

So, I had this 305 that I had gotten from my Dad - I put it together, installed it in the car in place of the one-foot-in-the-grave 350, and was happy. Yes, it was a 305, but it ran on all 8 cylinders and didn't smoke, and had more power than the terminal 350 ever did (it was the aforementioned L65 165HP 2bbl). Just one problem - less than 300 miles after installing the engine, the oil pressure dropped into the 10psi range at idle hot, and never exceeded 15-20PSI. The oil looked like metallic paint. Being a kid of 17, and not having a job, I put it together with available used parts and wound up grabbing a crank that was ever-so-slightly-bent, and it was eating the mains, which were then becoming suspended in solution in the oil. It did this with two sets of bearings before I replaced the crank (on money lent to me by a neighbor).

What does that have to do with the above? Probably nothing, just had to share a similar experience is all.

Now that you say somethign about startup, immediately during the initial rev, theres a coinciding rattle type know that lasts a split second. But a less severe rattle that I described initially comes at idle and just above any time the engine is under load (In gear) no matter what the temp. Now it's got a TH 400 bringing the power to the rear wheels through a 3.42 rear end, and I drive roughly 150 miles a week on the express way to work and back, the wole time the engine holding a steady 2500-3000 RPM because of the gearing, no overdive, and no torque converter lockup. How much worse does this make my situation?

Don't rev it when you start it! Give it a couple of squirts before you turn the key and let it idle into life. The higher RPM can't help you out here!

No no no no, I never rev it at startup, its got EFI, so it does it all on its own, and when its really cold out (winter) it holds an idle of 2000 RPM for a few minutes that can't be kicked down, because its trying to warm itself up... A down side of computer controlled engines I guess.

I just found out that running motor without cam buttom can cause cam to walk forward. i now need to remove cam and lifters and inspect for damage.
how will i be able to tell if a lifter is bad other than physical damage.

thanks for the help

I just found out that running motor without cam buttom can cause cam to walk forward. i now need to remove cam and lifters and inspect for damage.
how will i be able to tell if a lifter is bad other than physical damage.

thanks for the help

If your engine has hydraulic roller lifters, then yes you absolutely need the button. Pull the lifters out and check them, and also pull out and check the camshaft itself. If a lobe comes off the roller, the damage is usually lethal to both the cam and lifter.

Also, if the cam moves far enough forward, this can result in low oil pressure as you are exposing the oil passages to the air instead of a journal!

Excellent info.
I plan on diving in on saturday to find out.

Will keep you posted
Thanks again

I removed the intake today and found 8 lifters (2 on the right side, 6 on the left side)had rotated the push rod seat of the lifter causing the push rod to become jammed in the lifter.

Is this what they call a collapsed lifter?
That would probably explain why oil press dropped off the way it did.
Is this the kind of damage done by the cam walking foward?

After i removed lifters, i spun oil pump slowly and all lifters were getting oil. I guess i can rule out a oil restriction to the lifters.

The retaining clip of the lifters were still in place and lifters did not appear to have any other damage. All rollers were in good shape and no scoring on the sides of the lifters.

Inspection of the cam shows no chips or gauging and all lobes are smooth and none appear to have wiped lobes although i did not check with a dial. Cam rotates freely and there is no reason to suspect bearing trouble.

Most lifters were hard to remove I guess form varnish build up?
Should the bores be honed before installing new lifters?

Now that I have this thing apart, how to proceed?
Should i replace cam and all lifters?

should i replace lifters only?

If changing cam, should bearings be replaced also?
For peace of mind i should do both probably.
One thing is for sure, I WILL replace the cam button!
Since i have it apart, i will also put in a oil pump.

Any thoughts on this matter?

Thanks again for the help.

Al

You are almost to the point time and money wise where you might want to consider a reconditioned short block.

If you still want to reassemble it, go for a cam and lifters and oil pump. The cam bearings are probably ok, but would require an automotive machine shop if you want to change them. At that point, consider the short block option.

Look closely at your pushrod ends, if they're chipped or galled, replace them too. Roll them on a piece of flat plate glass to see if they're bent. The lifter bores should clean up quickly with a brake hone or by hand with emery paper or crocus cloth. Once the cam is out, wash down the lifter galley with solvent (carb cleaner is ok).

Bob

and make sure you change the oil before you refire the engine!

Do you think this problem was caused by not installing the cam button?
Before removing the cam, i tried to move the cam back and forth in the block and it only seemed to move only a few thousanths.
Could it have been enough movement to cause damage?
I just want to make sure i did not overlook something.

Quote: My personal guess would be a main bearing, especially if you can hear a 'thud' from the bottom end of the engine while it's under load.

In my '89 GMC w/ 112k, when I put it in gear, and whenever the engine is under even a slight load I get a sever rattling that sounds as if its originating from the bottom of the engine. When cold I get 30+ PSI, when warm its only 10+ PSI... Thats a bad thing right?
My 91' Caprice with a TBI 305 has that exact same noise as your GMC. Its really hard to pinpoint the exact location, but using a stethescope, it sounds like it may be coming from the lifters or the cam gear pin. I have yet to take the intake or timing cover off though. Its a rattle that I can duplicate by revving up the engine at idle and the second the RPM's start coming down you get the rattle, or under a slight load (like cruising), and occasionally at idle. Please let me know if you find the cause. I'm starting to get paranoid, but havent had the time to tear it down.
Thanks

If I find the source of the sound I'll let you know... I wont be able to do any serious investigating for a little while though. Another thought of mine is it could be the timing chain. At high mileage, the chains tend to loosen up, and become sloppy. If I find out anything, I'll let you know. If you find out anything first, be sure to keep me posted.