First of all, yes I have searched the internet far and wide for answers to my question.


Second, I am new here! And honestly only created this account because I am in desperate need of assistance, but have lurked on this forum for years. I hope some of you guys can help me out....



Just swapped another 5.3 LM7 into my 240 after my first one threw a rod. This time around I put in a brand new Melling oil pump, Improved Racing oil pan baffle/trap door system, and also needed new oil filter tubes that are internal to the GTO oil pan (GM PN 12556647). Also used the brand new pickup O-ring included with the melling oil pump. The problem is: I am getting ZERO oil pressure at idle, and only 20 psi when I rev and hold at 1500 rpm (verified with TWO oil press. gauges, one electronic, one mechanical). I have no idea why. Steps I have already taken to try and figure out the problem:


- Took the oil pan back off to check pickup to pan clearance, and there is about 0.32" between the oil pickup screen and bottom of oil pan. I also put on a new pickup tube o-ring where it goes into the oil pump.


- Took out the rear, angled oil galley plug to ensure the barbell is still in place, and it is. When I took the plug out, a few bits of what seemed to be oil sludge fell out, but it was only on the end of the plug, nothing further up where the barbell is.


- Took out the front driver side galley plug to check for blockage, and it was clear. I also tried priming the oil pump via Melling's instructional video (https://www.youtube.com/watch?v=539ClWWJMl8).


- Have already been through 2 brand new ACDelco PF46 filters, in case one may have been bad or something.



Now here is something I find weird....my last engine was running fine with the gto pan, oem filter, etc. (it blew probably because of oil starvation drifting on banked turns all day with no baffles, but anyways....) However, after looking at a diagram of engine oil flow through an LS engine (http://www.dpecorvettes.com/download...5_z%20copy.jpg), and tracing the tubes through the GTO oil pan, it looks like the oil is actually trying to go backwards through the center of the oil filter, and the internal valve in the filter is stopping it...but why?!?! especially when everything was fine and flowing smooth on the other engine???


Does anyone have any suggestions as to what might be going on??


BTW, I got the motor from a friend who was gonna use it for his own 5.3 swap in his car, but needed the money at the time, so i picked up the engine from him. He said he saw videos of it running in the truck it was pulled from, had 130k miles, and the cluster in the video showed good, factory oil pressure.




Here is factory oil flow diagram:


Here is the flow through the GTO oil pan:






am I missing something here!?!?!

 

Cam plate leaking? Rear main crossover leaking internally? Bad lifter? Stuck relief spring?

 

while i wont rule out bad engine internals, I just find it hard to believe that an engine that had good pressure from factory, now has 0 oil pressure, even with a HIGH pressure pump installed. I mean if it had maybe 30 psi or something, like the pump was trying, it might be a different story.

Just talked to Melling, and they are sending me another pump to try out, so, out comes the engine again. Have never dealt with Melling before, but they seem like a great company!

 

Although the crossover pipes appears to swap ports, they are indeed entering the filter in the correct port. If you inspect the internal passages you will see that it's correct.

You must have a huge oil leak somewhere. Maybe you're missing a gasket somewhere in the crossover pipes? Seem the likely culprit since you swapped them. Can you take everything apart and photograph in detail how you're assembling everything?

What about the pickup tube O-ring? Did you use a new O-ring?

You're not seeing any external oil leaks, correct? It must be something going on inside the oil pan.

 

Did you use a factory o-ring for the pickup tube. The last build I did I used an aftermarket one and had no oil pressure. Replaced with a factor one and got oil pressure. Never will I use an aftermarket one when the factory is like 6 bucks.

 

I used new gaskets in the pan on the crossover pipe connections.

Brand new O-ring, the one that Melling supplied to fit my GTO oil pickup tube.

no external oil leaks at all, everything is nice and dry on the external of the engine.

 

Oil must go in to outside of filter

Oil comes out the center of the filter.

All spin on filters work this way. ALWAYS!

 

Was the 5.3 completely disassembled prior to install?

If so, check the oil port on the front of the block behind timing chain cover. Make sure there isn't a hole where the cap is suppose to be.

 

the 5.3 was not fully disassembled.

I think I found my problem though....when I reset the oil pickup tube, I guess the angle I was at when looking at it wasnt very good, because now that I have the engine out and the front taken apart on an engine stand, I saw that the pickup tube was not fully inserted into the oil pump. even though it looked like it fully seated when i installed and re-installed it, it must have only been that one side that got tightened. so will install the pump and pickup this time before putting the front cover on so that way i can make 100% sure that it is seated fully and correctly!

 

You found it.

Install one of these http://www.ebay.com/itm/like/262471927301?lpid=82&chn=ps&ul_noapp=true

 

I forgot about these. Pretty sweet idea

 

late reply here, but I actually took that idea and made my own part out of some 1/4" steel. I never knew anyone made those parts, and never thought about it. but now that oil pickup tube isn't going anywhere!