Oil Pressure Saga
OK I just came in from replacing the o-ring. Not finished yet, I'm midway through putting the crank pulley on, damn it's a bitch too, got about a cm to go and I can't hardly turn it anymore. Anyway I'll get it the rest of the way with an impact tomorrow. About the o-ring though, the old one doesn't appear to be damaged but it is kinda square edged if you know what I mean where as the new one is fatter and rounded. It looks like it's supposed to be that way cuz it's too perfect, I can't see it being that square edged from being in there so long. I checked my oil pump spacers too and they were installed correctly. I don't know man I'd be willing to bet that this doesn't fix it either. But what do you, you have to cover all the bases right. To answer that last ?, I reused my old lifters, I haven't read anything saying that you absolutely shouldn't. I know it would have been best but money don't grow on trees here in Tx. I'll let you guys know what happens when I fire it up tomorrow.
TECH Resident
Joined: Aug 2004
Posts: 875
Likes: 2
From: Portland Oregon
That O ring is soooo delicate, if it is just a little twisted, you will get some pressure, but then it drops. That sounds like what is happening with your motor. If you had the pickup off and used the same O ring, it is a pretty good bet that it is not sealed.
I called the local Chev dealer and asked if they had a bulletin from GM on how to install the O ring correctly. A mechanic told me to get some 3M spray gasket sealer and spray the O ring, then install it inside the pump, at the bottom of the bore, then insert the tube. It's important that the O ring stays at the bottom. Several times I have put the ring on the tube to install it, and had problems, then removed it and found that it was up on one side and down on the other, that does not work. Buy a new ring. You have to remove the front cover and the pan. Let us know what happens.
I called the local Chev dealer and asked if they had a bulletin from GM on how to install the O ring correctly. A mechanic told me to get some 3M spray gasket sealer and spray the O ring, then install it inside the pump, at the bottom of the bore, then insert the tube. It's important that the O ring stays at the bottom. Several times I have put the ring on the tube to install it, and had problems, then removed it and found that it was up on one side and down on the other, that does not work. Buy a new ring. You have to remove the front cover and the pan. Let us know what happens.
Well guys I'm proud to announce that I now have 73lbs of oil pressure at cold startup at an idle!!! When I rev it up it goes beyond 80lbs. It's hard to believe that little o-ring can make that big of a difference. Oh and to the local mechanic who had me convinced it was the oil galley plug; you owe me $317 you jackass! That's what it cost me to have it replaced. I guess I should have went with my initial instinct huh. Oh well, chock it all up to experience I guess. Anyway, thanks to everyone for their input, advice and moral support(except that local mechanic dude) I appreciate it.
congrats, glad you got it figured out !! 
Im Haveing A Similar Problem.. I Have A 408ci And Have No Oil Compression. It All Started With My Pulley Coming Off Because I Used The Old Bolt(dumb ***) I Put It Back In And Then The Compression Was Good For A While Then All Of A Sudden My Oil Drop To 0. It Wont Go Up Or Anything. Because I Installed The Originall Oil Pump I Now Bought A New Ported One And Also Intalling It With A New Oil Ring. I Really Hope This Is The Problem Because People Told Me That Maybe When The Pulley Was Loose It Could Of Messed Up A Baring Or Something. I Havent Received My Pump Yet But Hopefully Next Week Everything Will Be Ok. Congreats On Fixing Your Problem I Guess From What Ive Read Im Going To Have To Be Extra Carefull With The Ring. Hey Motoxlifer Did You End Up Using The 3m Spray That Was Suggested?
So you removed your old pump after your pulley came off? I don't know man I would think you would have some oil pressure at least when you rev it up. No I didn't use the 3M spray. What I did was: I got the pump on the snout of the crank; then I got the pickup tube into the pump & got the bolt started; then I put my spacers behind the pump and got some of it's bolts started, but to where I could still rotate the pump slightly; then I tightened up the pickup tube bolt almost snug(still a little play though) & then started the rest of my oil pump bolts; tightened the P/U tube bolt all the way & then the pump bolts. This seemed to keep everything out of a bind & gradually put it in place so as not to force the o-ring & possibly pinch it or something. BTW I checked the oil pressure HOT and it's about 55lbs at idle (seems a little high too me). Anyway good luck with your issues I'm just glad mine are over.
