Hello all,


I know this topic has been beaten to death, but I've now become one of the people who's run into this issue. I recently had work done to my c6 from a local reputable shop, but since have had oiling problems. The car initially went in for just a cam kit/oil pump upgrade. After that was completed it was determined that the bearings were failing causing a oil pressure issue (The first time around we used a Melling 10295). We then replaced every bearing in the engine (Warrantied out the oil pump for another Melling 10295). The car proceeded to have oil pressure issues. We then tried a Melling 10296, and replaced the barbell. Which has brought it to its current state of cold idle 50-60psi/hot idle is 12-15psi. Oil temps around 230-240F warmed up. The car doesn't have any knocks or ticks.. The shop has assured me they made sure the O ring on the oil pump was not pinched, and the correct part number. They're thinking there's a possibility of a cracked block. Is there anything I could be missing here that would also cause a oil pressure issue? Thanks!


Here's a list of everything I've had replaced:


- BTR stage 3 cam

- BTR dual valve springs/push rods

- BTR timing gear/chain

- BTR LS7 lifters/trays

- CHR bronze trunnion bushings

- Melling 10295/10296

- Port/Polished stock LS3 heads

- Clevite Main/Rod/Cam bearings

- New piston rings

- ARP rod bolts

- ARP head bolts

- Powerbond dampener

- New OEM barbell

- New oil pressure sensor

 

Elaborate on "bearings failing." What are your bearing clearances now?

 

any chance a cam bearing has turned? Seems like something is blocked that shouldnt' be, or something isn't blocked that should be. The oil passage path is fairly simple but there are lots of places things could theoretically go wrong.

 

When I first noticed the low oil pressure I drained the oil and found a significant amount of bearing material. When we decided to move forward with replacing the bearings they found wear on the rod/cam bearings. As of the current clearances I'll have to ask them. I didn't think to ask.

 

I mean there's always a chance something could've moved around. I've looked around the forums for posts with people experiencing the same issue, and it all seems to point to the same conclusion. Bearings, or oil pump. Whether that be poor manufacturing, or improper installation.

 

Bronze bearings work by the oil pressure in the system, keeping a thin layer of lube as a cushion buffer between them and what is spinning against them.

So could be oil pump, or could be lose of oil pressure in the system from too large of gaps or missing O ring in the back of motor, but for main bearings to go out that soon, it was due to not enough oil pressure in the system to begin with to create the oil cushion buffer.

 

Does the pressure come up when hot at 2000 rpm?

 

The pressure climbs up when accelerating, but stops around 30psi. For example, at around 2,000-2,500 the oil pressure sits around 27-30psi. When I slowly accelerate up to 3,000rpm it stays around 30-32psi and does not go any higher.

 

I completely agree. The shop said they tried two different Melling 10295's, both with new O rings, and then the current Melling 10296. The barbell on the back of the engine is brand new, so unless it was installed incorrectly I don't see that being the problem, but anything can happen.

 

Could be losing oil pressure at the cam retainer plate or the valley cover O-rings.

 

Only when it's fully warmed up though? I'll pull the valley cover tomorrow to check the O rings out. The car is going back to the shop that did all the work next month. They said they'll get it taken care of at no cost, but if it's something small I can do in my garage I'd rather save the time.

 

Let the shop take car of it, since will bank not a simple problem but they forgot to check a clearance somewhere, is too wide and where the system is loosing oil pressure instead.

 

*UPDATE*

So I got the car back about two weeks ago from the shop. Crank was sent to the machine shop, and everything else was checked over. Apparently they really couldn't find a definitive answer as to why it was losing oil pressure. Been driving it around for a few days and at operating temp I was getting about 38-40psi. As of today, I took it out to get some breakfast and it started to develop a pretty loud valvetrain like noise while also dropping oil pressure. I now have 21-24psi at operating temp. It does climb up to 38ish psi when I slowly brought it up in speed. The noise doesn't sound like rod knock to me, but maybe someone here will have some insight.

 

Hey man, what were the bearing clearances when the motor was reassembled? If theyre loose,than can cause an oil pressure issue, and this could have been caused by the previous bearing failure.

Also, at 230-240 warm, the 15 PSI is lower, but still within spec. Its the 30 PSI at running RPM that would unsettle me. Have you cut open the filter off of the new motor yet? is the oil passage along the driver side of the block clogged with material? There's a port on the side of the block in front of the motor mount off the pump discharge that goes directly to the oil filter you could maybe install a mechanical gage on and check pump discharge pressure too. Its M18 X 1.5 IF i remember correctly.

just throwing out some options to try

 

I've asked for the bearing clearances, but haven't gotten an answer yet. I cut the oil filter open and found a very very small amount of silver shimmer, but I figured that was normal? They said to bring the car back to figure out the ticking sound you can hear in the video I posted. They said it could be a bad lifter, and if so, they'd take care of it. But would a failing lifter cause this large of a oiling issue?