I started up my 68 today and there was a strange tapping noise (sounded like rockers). The sound seemed to go away after warming it up. Then i noticed that oil pressure at idle was like 15psi. it is nomally 35-40. So i checked the oil and it needed a quart. After adding oil i started it and it was still almost NO oil pressure. The oil pressure DOES go up when i rev it and when im cruising it is like 70 psi.

Does anyone know what could be the problem here? Is the noise related to the low oil pressure???

Sounds like a rod or main bearing clearance problem. What was your pressure prior to this? Could also be the pickup on the pump, or the pump cover. I had a new pump that lost two of it's four bolts, and it was sucking air, causing SERIOUS detonation, as the lifters were pumping down. It had similar symptoms as you're experiencing. Remove your oil filler cap when it's at idle, and look for air bubbles in the oil flowing towards the return holes. If present, you're sucking air. Since that experience, I've removed the bolts, cleaned the threads on the bolts, and in the bores with laquer thinner, and used red loctite during reassembly on every oil pump!

Mike(Wolfplace) will probably chime in, and may have additional advice. Steve

15 at idle sounds normal. I guess its not normal if u had 35-40 before hehe. The minumum is 10 psi per thousand rpm, sounds like yur still in the safe zone. I wonder if one of those plugs behind the timing cover sprung a leak?

Oil pressure at idle has always been about 35psi. It would even get up to about 75 at 3K RPM. Now the max i got on the drive home on the freeway was about 40. I pulled in my driveway and watched it drop to NEAR zero. I guess the guage read about 4-5 psi at about 650RPM.

I didnt loctite the oil pump when i built the motor. I could be sucking air... that explains why im only getting half the oil pressure i used to. COuld the noise also be that the lifters are being pumped with oil and air causing them to not function properly?

Bubba,
Oil pumps do not need loctite. The first thing you need to do before you run the engine for even another second is to take the oil filter off and cut it open to check for bearing material. If there is any evidence of bearing material in the filter its time to take the engine completely apart and find out why. If the filter is clean, its possible that the oil pump relief valve stuck open, but it is rare. Either way I would not run the engine any more until the problem is found.

Bill; Just going by experience. I agree it was a freak occurance, but within two months of the engine build, I had the same exact symptoms as Bubba. There were air bubbles coming from the pushrods, and when I pulled the engine and pan, I found one cover bolt in the pan, and one hanging by a thread. The cover was gapping very slighty, but it was all it needed to suck air. I appreciate your knowledge, but please don't make a broad statement that basically undermines my actual real-life observation. I was just trying to help, and the loctite is good insurance, just like welding the pickup tube! Steve

did this happen after changed the oil??

Steve,
I thought that bubba was referring to the main oil pump bolt. Personally , I have never used loctite on any oil pump bolts, including the cover bolts and have never had one come loose. Lucky ?? maybe so.

i changed the oil about 3 weeks ago. Ive been running 30wt and have been getting good pressure. Oil is still clean as honey.

What is the relief valve and how does it get stuck open?

I did have to drive it home last night, but oil pressure was a good 30psi all the way home, i just had to keep the rpm's about 1500 at stoplights to keep the pressure around 20. But again, when i let it idle at 650, oil pressure is almost non existent (3-4psi).

COuld something be clogging the pick up screen? Gasket material?

bubba,
Could be a lot of things including the oil pump cover bolts, oil pump releif valve, one of the oil galley plugs in the block etc. By the way, are you certain that the gauge is ok ?? Might want to try another one just to be sure, but I would not run the engine very long. You are probably going to have to take it apart to find the problem. Did you cut the filter open yet ?

Not to certain about the guage. I would think it was just a bad guage but the engine is making a clicking noise. Its not a deep knocking sound but more like a fast tapping sound at idle that seems to be coming from the top end.
How do i go about cutting the filter open? i have a metal bandsaw, but i dont want to see shavings from the filter and think they are bearing shavings...

Bubba,
I have a filter cutter, looks like a big tubing cutter, but you can use a pair of tin snips as long as you are careful

If i WERE sucking air through the pump, what effect would that have on hyd. lifters?? Im hoping that the ticking is just the lifters full of oil and air.

Is this a possibility??

Bubba

p.s. Is it just me or am i constantly having problems with my velle?!?! I love the car, just wich it wasnt my daily driver

Originally posted by bubba68ss:
If i WERE sucking air through the pump, what effect would that have on hyd. lifters?? Im hoping that the ticking is just the lifters full of oil and air.

Is this a possibility??

Bubba

p.s. Is it just me or am i constantly having problems with my velle?!?! I love the car, just wich it wasnt my daily driver =
If you get air in the oil the lifters very well could make noise as will lack of oil but as Bill has already stated, you need to find out what is going on before you do any more damage.
You could have a pump problem of some sort.
An internal plug could have come out of an oil galley, the filter could have come apart & is pluggin something up, or it could be something to do with the gauge although I doubt it with a new "noise".
Is the engine missing? If so it could have kicked a lifter out of a bore,,, the list goes on & anything said here is no more than conjecture.
Bottom line, do as Bill suggested, quit running the engine & find the problem before it gets real serious if it isn't already.

On a brighter note, although it is possible it's bearing related, it is very rare to loose that much oil pressure or have a "sudden drop" like that from a spun bearing.

Seem's like the more power you make the more problems you have lol. Or you don't drive it as much as you make more power, so you don't have the problems. Stock sure is trouble free. smile.gif If the lifters aren't getting enough oil they will tick,and that will sound like top end problem's because the cam turns twice as fast at the crank. Also there are 16 lifters. Generally a mechanical gauge won't fail, but sticking another gauge on for comparison can't hurt anything cept lighten your wallet a couple bucks.

Originally posted by 19Nova72:
Seem's like the more power you make the more problems you have lol. Or you don't drive it as much as you make more power, so you don't have the problems. Stock sure is trouble free. smile.gif If the lifters aren't getting enough oil they will tick,and that will sound like top end problem's because the cam turns twice as fast at the crank. Also there are 16 lifters. Generally a mechanical gauge won't fail, but sticking another gauge on for comparison can't hurt anything cept lighten your wallet a couple bucks. =
Actually, the cam turns half as fast as the crank ;)

No, the engine is not missing. Runs pretty decent. I suppose it could be running bad if there is air in the lifters... I remember checking the dipstick to see if i had oil and i was half quartlow... but i THINK i saw little popping air bubbles on the dipstick...maybe just hallucinating
Ive heard engine knocks before that were obviously bearing realted, and this doesnt have that sound like they did. It sounds just like the rockers did when i was adjusting them for the first time. Thats the kind of noise i am hearing. So i hope its not bearing damage, and just unpumped lifters.
So should i check for bubbles in the oil before i pull the filter off?

Sorry, I had a few beers lol.

As a buddy of mine use to say, "Run it until it breaks, then you'll know what was wrong."

Originally posted by Pat Kelley:
As a buddy of mine use to say, "Run it until it breaks, then you'll know what was wrong." =
lmao graemlins/beers.gif

Sounds like job security for us starving machinists :D