ACE1252

Guys,

I'm having oil pressure issues. I had this issue piggy backed in someone else's oil pressure thread, but have decided to give the issue it's own thread.

For years it has been my observation that the oil pressure in LT1's take a small dip(5 psi), @ wide open throttle, around the 5000 range and then comes back up to around 55psi before the stock redline.

Now my engine is developing a different problem. In first gear, when I go wide open throttle, the oil pressure comes on strong until around 3500 then starts to fall off until 5000 when it then will come up to 60psi and stay. When I go to 2nd the pressure still stays at 60psi.

Here is a video of what it's doing. You can pause it, then pull the slider slowly back and forth to see what it's doing better. The movie is a .mov and is 32megs in size.

http://youtu.be/IjclVu1HYYM

The other curious thing it's doing is, when in 6th gear cruising, I can go from light throttle to wide open(leaving it in 6th) and the oil pressure will drop 5psi. Lift from wide open and it raises 5psi. Could this be thrust bearing issues?

I have changed oil from 5W-30 to 10W-40. That has given me a 5psi boost in pressure all the way around, but has not solved the dip in the pressure from 3500-5000 when going from a dig or slow roll.

The pickup is not in the bottom of the pan and I think the sending unit is fine(however I will be swapping it soon). The oil level is fine too. I installed the GM white high pressure spring when doing the cam.

I've been doing research on here about oiling issues and I'm not convinced that a new pan or windage tray will solve my issue(I have stock pan and windage tray). My logic is that I've never had this issue before, so the pan and windage tray should be fine for my current setup.

I'm not sure what my problem might be so I need some opinions on LT1 oiling issues.

I've sent my oil to Blackstone Labs for analysis. My worst fear is that something is going on that is related to my cam swap(bearing problems). So I'm hoping the analysis comes back normal on the bearing wear.

I dread this because my tranny is in need of rebuild and to have oiling issues pop up is really bad news.

If I was driving this car as a daily driver, I would just go easy on it and let it go til it blows(if it was stock parts and stuff)....but this thing is going to be used for many a track outing....and I know I need to solve this before taking it down the track anymore....or I will, for sure, end up with a paperweight.

Any opinions or suggestions are welcome.

Oil pressure @ hot idle is 35 psi(10W-40). Cold idle is 60psi.

ACE1252

I got some good news today. My oil analysis came back today. They said the wear was below normal. The only thing they found high was silicon. They said that was normal due to the right stuff I used to seal the oil pan a couple of months ago.

I had never had one done before, so for those interested, here is my oil report.

http://www.ace1252.com/96Z28_Oil_Ana...stone_Labs.pdf

Blackstone labs done the analysis. You just plug in your address on their website and they send you the kit no charge. Then you collect the sample and for $22.00 they perform the analysis. You can put comments and such on the form(I put that I was looking for abnormal bearing wear). Some good stuff.

I've spoke with my Dad on my issue(he used to build circle track race engines back in the 60's).....and he feels that either my sending unit, oil pump, oil pickup, or pan issues could be causing my problem. He does not suspect any bearing problems, because of the nature of the pressure problem(which my oil analysis confirms).

So...I guess I'll just go easy on it for now and try to repair it when I pull my tranny out for a rebuild(so no track time).

I hate to shotgun the problem, but I guess I'll replace the oil pump(Melling M155), Moroso oil pan(20185), and Moroso pickup(24212). I'm not sure what else to do.

The pickup should be 3/8" from the bottom of the pan correct?

ACE1252

This pickup that goes with the Moroso pan....

http://www.summitracing.com/parts/MO...2/?image=large

It bolts to the oil pump correct? I know it says press in fit, but that bracket on the pickup looks to bolt to the oil pump.

wrd1972

I would weld it regardless. You dont want it possibly sucking air at the joint either.

ACE1252

Cool deal. I can have my Dad weld it all the way around. With the bolt on bracket, that should set it at the proper depth correct?

Edit: My Dad did braze it to the pump. The bracket did set the proper depth for the Moroso pan. Should also work on a stock pan as it is the same depth as the stocker.

ACE1252

This is old, but I'm bumping it to report what I did to fix this issue.

The problem was oil running away from the pickup on acceleration.

I used a Canton 20-013 pickup and Moroso 20185 oil pan.

That solved the oil pressure dipping problem. I did both at the same time(so I can't say if one or the other was the solution), but I do feel that the pickup did more for the problem than the pan. The Canton pickup centers the pickup in the pan where as the stock pickup is very close to the front of the pan.

Results of the fix....

8cylinders>4

I had the exact same issue with my stock engine. No issues with new engine Im running the same Canton 20-013 pickup, Moroso 20185 Pan and Melling 10554 Pump.

So nice to be done with the anxiety of dropping oil pressure everytime I was getting on the throttle.

In my case it seemed like exactly the same issue. The pressure would drop severely in 1st and 2nd where the acceleration G's were the highest, it would drop from about 45 psi down to 25 psi and then raise back up again towards 5000 rpm.

In 3rd it was a little less dramatic, it would do it slightly in 4th as well.

8cylinders>4

I should add that the oil pressure dipping issue was not the reason I built the engine. Here are the mains from thrust to front. You can see that the front most bearing was partially starved over the years. As well as the need for a line hone considering the thrust bearing was barely touched.

The rod bearing had a very similar wear pattern, the bearings closer to the oil pump were in better shape than the ones up front. None ever spun though. This was with 150,000 pretty aggressive miles.


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This is the reason the engine was built, I actually had leakage in on all 4 corners (cylinder 1, 7, 2, and 8. I attribute this to a failed stock fuel pump causing detonation.
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