Ok, 2015 Camaro, 89k miles, LS3, manual transmission.

This has been almost a 2 year saga for me, and I’m looking for guidance on the next step.January 2024 broke a single valve spring on a calm cruise, all stock internals engine. Shut down and parked within 2 miles. The spring was mostly intact, but the valve made very light contact with the piston. I took this as a sign to upgrade with the following (all new OEM or better parts):

Trickflow 255 assembled heads
7.70 pushrods per trick flow instructions
BTR Delphi lifters
lifter trays
timing gear
timing chain
head gaskets
melling 10295 oil pump (stock volume, high pressure) used black oring (green won’t fit)
TSP Bald Eagle cam
cam retainer plate
ATI super dampener
new oil pickup tube
oil pickup tube girdle/second bolt
Blocked oil pan pressure relief valve
removed and blocked oil cooler
fresh Mobil1 5w-30 oil every time

First start had great cold oil pressure but low oil pressure (10psi) at idle once hot. so I put in a new oil pump pickup o-ring, but no change. Same issue, did this twice.

Then I cut the crossmember, welded in brackets, dropped the pan, and put in a new pickup tube and o-ring, removed and blocked off the relief valve, removed the oil cooler, and blocked it off. Fresh oil, same problem, no change.

This all took almost two years due to family, health, time, and money.

What’s my next step? Any ideas? I’ve read everything I can find… Bad cam bearings? Bad lifters? Wrong pushrods? Bad oil pump? I’m frustrated, confused, and angry.

I have some more parts on the bench, but want to avoid just throwing parts at it:

melling 10296 pump
external oil pressure gauge

Thanks,

Howell in Tampa

 

I had similar issues with a LS3 rebuild. Tried the same things (oil pump, O ring etc...) Issue was the cam bearings which were new clevite bearings. The were replaced with durabond and the oil pressure issue was resolved. The machine shop that did the work had mentioned issues with some cam/cam bearing combos which really didn't make a lot of sense. They had mentioned one customer who tried installing their cam after bearings were replaced and found it too tight while the shops "house cam" slid in perfectly fine.

Since your cam was replaced I would look closely at the bearings/cam journal clearances and cam retainer plate.

 

As Vegas said, I’d suspect cam bearings. I’d start with cutting your oil filter apart…with the correct $40 tool….and look for debris. Filter media will always tell you your bearing condition, and will never lie to you. If there’s debris, you’re 100% sure it’s cam bearing(s). If it’s clean, maybe a bearing walked a little. I’ve seen more than one camshaft show up .0005”ish out in the center. Oddly enough, due to angles, the 2 & 4 bearing journals will typically get bearing pushed over because the cam journals are spinning at an elliptical, not a true circle. Hope I’m totally wrong here, but it’s about got to be this. I could have told you 2 years ago that it’s not the o-ring on the tube. 99.9% of the time, it never is.

 

Thank you both for confirming what I have been thinking. I will cut the filter open, should have done that long ago… this is now the third oil change and filter since the heads and cam were replaced.

 

Report back with findings. Here to help!

 

If oil pressure was good before it may be a bad cam unless the cam bearings were damaged during the removal/install. I don't think you will find much in the oil filter as when I was having the warm oil pressure issues the oil and filter were both fine. Does warm oil pressure increase when revved?

 

Yep, warm oil rises with rpm to “normal” levels. The cam is brand new, but I plan to pull it and check the journals before throwing in the towel for a rebuild.

Going to be a bit before I have the time to tear back into it.

 

I'm real sorry you're having these problems. I had a cam bearing walk on me years ago. It was the last one in the rear of the block. As soon as it uncovered the oil feed hole, pressure dropped to zero. Had just 600 miles on the rebuild. This is another place that the original SBC has an advantage over the LS series. That would be priority main oiling vs the LS oiling the lifters and cam bearings first before the mains and rods. My engine might've run awhile if it had priority main oiling. Who knows......

 

The WW2 era SBC oils the mains & rods via a groove cut around each cam journal behind the cam bearings. It has 3 front <–> rear passages along the cam tunnel; the one above the cam oils all the bearings, with oil arriving at the crank after going around the back of the cam bearings, while the ones on either side oil the lifters. The LS motors have 2 front <–> rear passages along the cam tunnel; the pass side one oils those lifters only, while the driver's side one oils both the lifters on that side, and the crank. So, neither can truly be said to be "priority main", like the big bock Chevy is. That design has a front <–> rear passage along the driver's side of the block near the oil pan rail, below the water jacket on that side, that oils all the bearings, plus 2 along the cam tunnel that oil the lifters. Both the SBC and the BBC require the distributor housing to be in place for the system to work, since that necessarily intersects the pass side lifter passage. There are 2 raised & machined rings around the dist hsg that mostly somewhat seal to the block where they meet it, to maintain the integrity of that passage around the dist.

I doubt that any design of passage ordering would survive a cam bearing uncovering its oil groove, even though those passages are typically pretty small, like ¼". Even so, it would be such an enormous leeeeeek that it would likely be impossible for the pump to move enough oil to maintain pressure, especially hot.

 

Learn something new every day. I probably knew this years ago, but memory now isn't what it once was. But in fairness to the SBC, the oiling system in them didn't need much attention. I had a 383 stroker back before they had "kits." Took a 400 crank and ground down the mains to fit the 350 block. Never had any problems with anything in that motor. Lost it and the car to a divorce......

 

I agree. For the same reason, I don't consider the LS system "defective" or "inadequate" or any of that, for the purposes of about 99% of us. There's always those few outliers that stretch everything to the limit, but that takes quite a bit of effort in these motors.

The "hone to fit" cam bearings though, are a PITA. Reminds me of the babbitt metal bearings in the Model T, that you melted the metal and poured it into the mold, and then after it cooled, honed it out to fit. STONE AGE. Completely uncalled-for in the 21st Century. Even the old SBC was better built than that. Butt I guess It Is What It Is, no matter what I think about it.

 

NOT an engine Builder here.
I have done a little bit of tuning, some parts swapping and I have 3 aftermarket LS camshaft installations in my daily fleet- ALL 3 are Texas Speeed cams, stuffed directly into high mile engines with "ORIGINAL cam bearings " I never even LOOKED at the bores-Haha...

--- My next project will get a lot deeper into an LQ4, complete tear down, intending cylinder hone, gapped rings for boost, BTR cam, new oil pump, etc.

I have not yet installed Gen3 LS cam bearings.... Are you stating that LS Cam bearings are NOT precision bearings,taken from the box, as shipped- press in bore, and serviceable "AS FIT" ?

Is it just DuraBond cam bearings that Go In Undersize ? Are Clevite/Mahle also "too tight" out of the box??

 

The cam bearings are a press fit and it depends on the block and the cam core... It's the responsibility of the builder to check the clearances. If the bearing doesn't go in straight, or debris gets under it, that could affect the fit.

Same thing with the Cam Core. There is more than 1 company that makes the blank cores. The Main journals are already finished on the core. The Cam Grinder just finishes the lobes to whatever you order. If the Main Journal is out of spec, you can also have a fitment issue.

 

From what I have learned about the LS engine is the #2 cam bearing is one that can wear and bleed pressure. Now many stock shafts the #2 journal has an oil groove machined in to help distribute oil throughout the engine. Was this also a DOD delete build?

 

I will say one thing about the engine that had the cam bearing walk. That would be that I'm not a fan of the GM cam bearings. Reason being that I remember when I bought them at the dealer, I got them home and outta the package, and checked the "roundness" of the inserts. I was amazed that they were all about .013"-.015" out of round!! Maybe most guys don't do that, idk. At first I thought maybe the one I checked had been somehow "tweaked" out of round. Not so, they were all the same! Apparently, GM depends on the press fit in the blocks cam bores to make the shells/inserts round. I would much rather see the bearings be round to start with, and not depend on the block to make them round after being pressed in. Does anyone know the purpose of this practice? Has anyone else experienced this???

 

.
.
. NONE of the four factory LS cams I have removed had a grooved cam bearing journal like that.

 

I've been building engines for over 40 years now; not so many LS ones, I don't do much of that anymore.

If a EFFFFFING World War 2 design (the 262.5 / 265 / 267 / 283 / 302 / 305 / 327 / 350 / 400) and a mid 60s design (366 / 396 / 402 / 427 / 454 / 8.x) can manage it, there's NO EXCUSE WHATSOEVER for a late-late 20th century design to lack precision in that area. Again, not saying "it doesn't happen"; just, there's NO EXCUSE for being unable to buy a set of cam bearings off the shelf, install them in the same way we've been doing it all these years, and for that NOT to work. That's just ... some kinda ghost of a hangover from the Malaise Era I guess. I CANNOT BELIEVE that it's not possible to get this right in these motors, after ALL THOSE YEARS of it being just fine in all those others, except that I HAVE TO, because all manner of people that can be trusted to get it right if it COULD be gotten right, can't. It literally would have required DELIBERATE SABOTAGE on someone's part to EFFFFFFF that up. Butt apparently GM managed it in spite of how STUUUUUUUUUUUPID it is. If it was up to me, once I found the IDIOT or MORON or IMBECILE or whoever it was that EFFFFFFFFFFFED IT UP, I'd quote the Big Orange Guy: "You're FIRED!!!!"

 

This is a VVT camshaft. Oil is forced into the cam on that journal. It’s the oil pressure that holds the VVT phaser steady and the ECM controls the phaser.

 

OP, before you tear into the cam bearings, plug your oil cooler back in. IDK what oil you are using, but all oil loses viscoscuty as it gets hotter. You may be cooking the oil with a heat issue, which is why it good when cold start. At least try that and report back.