I have a lq4 bottom end with about 100k miles with ls3 heads,cam, and intake i have ls7 lifters also. but anyways here lately i have been losing oil pressure when it was first done a cold start up was between 60-75psi and hot 40-55ish psi and now a cold start up is 40-55ish and warm is 20-40 psi i'm not sure is maybe i have a bearing going out somewhere or what? I don't think the sender would be going bad since its been getting slowly worse and just not appeared all of a sudden. what do you guys think it could be?

 

You might try hooking up a mechanical gauge for comparison. I've seen examples where the oil galley leading into the digital sensor, can become gummed up over time, leading to erroneous readings.
Cut open your oil filter, and inspect for bearing babbitt. Use a can opener or pair of needle-nose to cut it open.
Also, inspect your oil by emptying the majority of the oil, slowly, into another container. In the container with the remainder of the oil, inspect by moving the oil around. Sometimes, the oil barbell can become unseated, and this will allow oil to bypass the filter. Checking the oil in this manner might expose the possibility of this situation. When inspecting the oil, I will place a clean plastic garbage bag within the container, so that if there are no contaminants, the oil can be reused.

 

Same thing happened to me after I did my H/C/I/E swap. I thought for sure something was seriously wrong. I replaced the OPSU and that was it. I didn't think an OPSU would go bad like that.

 

Was going to say the exact same thing as gMAG. That is the best way to go about diagnosing it.

 

ok i will have to do that in the next day or two and if that doesn't come up with anything ill have to try a new sensor.

 

Well it looks like there's bearing material in the oil damn it looks the motor will be coming back out i think it's the cam bearings though

 

Is the oil pump original?

 

No the oil pump was new from advanced auto parts

 

James,

Hope you get it repaired, soon. It will be easier to repair, because it seems as if you caught it before there was severe damage.
Same thing happened to me last year.
Are you doing your own work?

 

I will be pulling the motor out and getting everything ready but i will most likely have to take it to a Machine shop to take the old bearings out and put the new in because I don't think I can do that. Also what bearings should I go with?

 

Your choice, of course! It also depends on how soon you need the car back.
If you can pull an engine, you can replace bearings, with the correct tools...cam bearing driver ($100?), angle driver for stock rod bolts. You can reuse all bolts but the rod bolts.
King bearings (standard size, as long as the rods haven't been altered) work just fine, are price friendly, and are used by quite a few, here. These are LS6/LS1 bearings. You won't need "race" or Hi-Perf Bearings.
Summit carries them, as well as ebay, and sponsors here.

http://www.ebay.com/itm/Chevy-Pontia...988e3a&vxp=mtr
The vendor, here, has all of the King bearings, including cam, w/free shipping.

Some folks in the know, recommend checking & resizing the rods when changing the bearings. Some just change the bearings.

 

So you think I should replace all the bearings while I'm in there? And since the cam bearings aren't that hard todo I'll just do them myself and I'm in no hurry to get it done because its not my daily driver and it's going into winter

 

This is good! You'll have all winter to get 'er done.
What I would do first, is to remove the engine & get it on a stand.
I don't know exactly how much bearing material was in the oil, but would first remove the timing cover, intake, & valley cover. Then pull the cam & see what those bearings look like. Shining a flashlight down the tunnel, you can inspect the cam bearings. Good bearings can still have wear/abrasion marks.
But they shouldn't be scored or have pockets of metal missing. It's your call whether to replace them @ 100k. Some people go to 200k without the change.
If you don't need to replace them, you've eliminated having to remove the rear cover. But, because the engine is out, it's also your call to replace the rear gasket & crank seal (& the oil barbell).
Ok, if the cam bearings look good, maybe you've decided not to touch them.
In this case, tip the engine over & inspect the rod bearings, one by one.
BEFORE REMOVING ANYTHING, MARK each rod cap & crank main cap by number AND direction, with a punch set ($6 @ Harbor Freight). The rods are "cracked"...that is, the process of creating/manufacturing the rod involves cracking them apart. This means that the joining surfaces to each specific rod are unique, & will not fit any other rod or cap.
Then, pull all rod caps. The pistons can then be pushed up into their bores, and the crank caps removed. From here, pull the crank (it helps to have a friend hold certain of the rods, and hold them out of the way while the crank is removed. Likewise, when the crank is reinstalled).
When reassembling/torqueing the new (GM) rod bolts, you'll need an angle wrench. There's another name for it, but I can't think of it at this time. As an alternative, I used a plastic protractor, to find the proper angle-85 degrees.
LS6 rod bolts (#11610158) will do fine. They're about $2.70 ea @ GM PartsDirect.
You can reuse all of the other bolts.
You can do all of this with the heads on. No head gaskets needed.
Then, order the bearings you'll need, and buy some red (permatex?) engine assy lube to butter up the new bearings & crank upon reassembly.

 

Okay I'll have to do that then so you don't think the main bearings are the problem? It's just the cam or rod bearings?

 

Never mind I see where you said to check the mains too I just read the reply in my email at first and it didnt have everything in it

 

I'll take a guess and say that the mains are fine. This is because you didn't have a catastrophic pressure fail.
Just a guess...that your #7 rod bearing is about to go.
As an example, see the pictures near the last page of my build.
Again, it's your choice, after inspecting, how much you want to replace.

 

thanks for all the help also do you think it would be worth going ahead and using arp rod bolts?

 

You gotta resize the rod for arp bolts...

 

If you go "by the book", you'd verify the rod sizing, no matter which rod bolts you go with. Again, your choice.
You know, as long as everything is apart...take them to the shop & check them. If you decide to check them,, maybe you'll buy a tool to do so.
Unless you're revving up to 7k & beyond, I wouldn't do ARP.
GM LS6 bolts are good enough for the Corvette 405hp (& much more).
I've used them this season, and occassionally spun them @ 7k. I don't recommend this on a steady basis, though.

 

okay my car redlines at 6600 anyways so i won't worry about that then lol