I posted something about this in the lt1 tech section but I wasn't getting the answer I was looking for.

Problem: When Hot, under hard acceleration, oil pressure will drop from 45 psi to 25psi around 4k rpm all the way up to 5k. It only does it in 1st and 2nd when the car pulls the hardest.
I've got 4 quarts of mobil 1 10w-30 in it and 1.5 of 15w-50 with a delco 1218. Still have stock cooler on it and I just replaced the pressure sending unit. When hot, cruising pressure is around 45psi and idle is about 25 psi.

I've come down to two conclusions:

1.Oil is being pushed towards the back of the pan while accelerating and its not picking it up. But why is it doing this after 73k miles?

2.There is cavitation inside the pump.

What would be the best way to solve this problem. I've tried adding a half a quart over ful and that didn't help. Should I get a new high pressure pump? What kind would you suggest?

Thanks fot the help before hand guys. I really want to get this fixed because I don't think it is good to spin her up to 5500 with only 25 psi.

 

if nothing has changed from befor, meaning you haven't over heated bad etc etc, then it would point towards the oil pump. If you acceleration has changed (meaning you have done work to your motor and it now pulls alot more) then maybe it could be an oil distribution problem. The way you've describe it is that it never did that and now for no aparant reasons it is doing it, which would suggest the pump is the problem.

Meeling pumps are good

 

Thanks for the reply. Looks like I'll be pullin the pan in the next few days.

 

The one thing i noted is that you said you still have the cooler. I personally would try removing or bypassing it if possible, as i have read tons of threads where that is the culprit with strang oil problems.

 

Ya I was also thinking about that, but the problem is at hard acceleration. I can just sit there and rev it up standing still and my pressure will be fine. Or I could redline it in 3rd or 4th when there aren't as mcuh Gs on the car and I wont have a problem. From what I have read the oil cooler is a low pressure all the time thing. So I think it is has to do witht the pump and pickup. Not to metion I was going around a turn the other day and my pressure went to 0. I turned it off right a way and restarted and it has been fine. So now I just have to decided on a good high pressure oil pump and one the preferably comes with a pickup.

 

You might also want to make sure that your oil pickup did not fall off the pump and that it positioned correctly at the right level in relation to the oil pan. What I do when installing a new pickup to set the level is to install it lightly into the pump so you can just move it and then purposely set it too low (so the pan won't go on all the way) and then install the pan without a gasket which will push the pickup up and when you put the gasket on, you will be afforded the clearance between the pan and pickup that is required. Of course, you could always be starving the oil system but I doubt it with 5.5 qts in there. I am running 6qts in mine but I have an air-to-air cooler that holds about a qt total itself.

 

I thought you said it was fixed here?
http://web.camaross.com/forums/showt...hreadid=143741

 

Ya Ken I thought it was too. When I took it up to 5k I was standing still. I added the oil waited a while for it to heat up then revved it and it stayed around 5k. I though the car was ok until I took it out. Boy was I wrong.

 

Ok I'm not happy. I just changed out my oil pump with a melling and a shimmed spring. I have 60 psi's while cruising and 30 at idle when hot. When I get on it I have 70 psi's and then about 3 senconds later while accelerating hard, the pressure drops from 70 to 25. It sounds like I'm running out of oil. I have 6 qt of 20w-50 in there with a 1218 filter. Should I try adding another 1/2qt or just leave it? Do you really think 25psi's for 3 senconds is really hurting it? When I took off the pan it looked spotless. I couldn't find any shavings. Cam looked good and so did the cylinder walls.

 

I would check your rod and main bearings clearence. I believe your motor is loosening up. and no you will not necessarily see metal in the oil. As you increase rpm you also increase load which when having a looser motor will sometimes cause what you are describing. A sbc has one of the best oiling systems of the big 3. If you take your pan off again I would use plasti gauge to get a idea. Maybe pull 1 main and 2 rod bearing caps to measure clearence. if nothing else you will have a piece of mind if everything looks good. Be safe before it turns out to become a loud knock. Good luck Andel

 

I appreciate the replies guys. The thing I don't understand is that if it were my clearances opening up, how come my oil pressure doesn't drop while revving it up and not moving? The other thing I don't understand is how can 6qts of oil miss the pickup and why did it all of sudden start now after 73k? I mean, its got to be running out of oil if it drops from 70 psi to 25. Man this is frustrating. Low rpm stumble for the past year and now the car gods decide to give me this problem on top of this.

 

The mileagae on the car 73K, things can happen especially if you been making passes. On most dedicated drag cars we will pull down the motor after 100-125 passes. We even take the valve covers off every 4-5 passes. Now I know I am talking about a race car but it still applies to yours 73K which is a lot of miles if you have been running hard and how many runs have you made even on the street. Free reving things sometimes can happen differently then under load. Its like just free reving and nothing happens and then you put it in drive and hold the brake (if auto) and try to torque it hard, the motor lifts to one side and a huge load is on it and it might even ping. The motor is trying to over come a resistence which makes it work harder. Since you have replaced the oil pump and checked the pickup the next step would be maybe checking the clearances. Hope somebody else might have a better idea for you. goodluck

 

We'll after doing some thinking and reading I've decided that maybe I should get a better windage tray and an oil pan baffle. From what I have read, people with the same problem as mine have solved it with a new oil pan. I was thinking about going that route, but after hearing all the problems people have had with canton oil pans I decided a better route would be to modify my stock pan. I was thinking about this tray and this baffle . I'm think that the combination of these things will fix my problem. I believe that the stock windage tray isn't letting oil down into the pan fast enough because it only has one hole on it for the dipstick. Plus the baffle will help out alot because it will help keep the oil in the bottom when I accelerate. One other idea I have is to try to find a different pickup. I was thinking that one closer to the back would be better for when I accelerate. Do any of you guys have a better idea for a pickup? What do you guys think of a new tray and baffle? You think that will fix it?

 

Yes both look good we have used both of those, since your going to go this far then I would also go to a cranksfaft wiper also. Just needs to be fitted. The tray will require studs I believe. My concern is still that your problem just started if I'm right. I would still check clearances. Now if your problems were right from the start then I would say yes try the windage items. So while you have the oil pan off I would just check the bearings for peace of mind. Rember your telling us it just started on a motor w/73k. Something is causing it to do this. I don't think installing those parts will cure it. My personal opinion. I'm over 40 and been building sbc since I was 17and before that working around my dads shop since I was knee high .Have gone 7's in 1/4 mile in a race car to 10's na on street tires on a street car. All have been sbc or bbc's. All have been built by me except machine work. But with this fuel injected stuff I am totally lost. But with help from guys here like you I'll be back in the saddle again. sorry to go off tangent Andel

 

Ya I was gonna pull a few of the mains off and check them with some plastigauge. Ya the motor has 73 on it but it really doesn't have much abuse on it. I bought the car with 60k on it and the guy who I bought it from was a 60 year old who never got on it. The tray should bolt up right I think. My stock tray has 3 studs so I'm pretty sure it should bolt up. I think the only thing I'll have to do is cut a hole for the dipstick.