tommypenguin

For reference I am driving an 01 supercharged c5, with stock ls1 bottom end and ported ls6 heads with beehive springs and a very mild thunder racing cam and pinned crank. I have just shy of 75k on the odometer.

Unfortunately I have run into my first significant issue with my c5. I was driving home from a car show on Sunday and was a block away from my home and saw a neighbor. I stopped the car to chat with them and upon starting the car saw my oil pressure at 0 and the low oil pressure warning came on screen. I was surprised to say the least.

The car sounded fine, and I could see my house, I made the decision to drive it a block instead of getting it towed. Upon driving the car for a block I didn't notice any mechanical sounds and oil pressure went up to 50 or so and then after pulling into my garage at idle the oil pressure needle sunk down to zero while at idle, I shut the car off at that point.

What I have done so far is...

• Check Oil, it was full requiring no addition of oil. I run Joe Gibbs LS30 oil and use a K&N oil filter.
• Replaced Oil Pressure Sending Unit, started car, saw zero oil pressure. Pulled new OPS and saw it was still dry.
• While new OPS was removed and OPS bung hole was open to atmosphere I set a shop towel on top of open OPS port. Then disconnected all coil packs and tried cranking car to see if oil would prime up through the open hole onto the towel. No oil hit it indicating oil is not making it to the heads at startup and likely idle.
• Appears based on my very small sample size OPS is only seeing oil pressure under load and definitely not at idle.

At this point I'm thinking the likely culprit is the oil pump potentially because the relief valve is stuck open. However, before I start venturing down that path are there any other troubleshooting steps I should do prior to swapping oil pumps?

If not, should I proceed down the oil pump replacement path, what oil pump should I replace my stocker with? Melling is a common one I've come across but haven't seen a specific part number I should select. While doing an oil pump aside from the water pump are there any other maintenance parts I should replace. I was planning on using the install guide from ls1howto unless others have suggestions?

Any advice or considerations I'm not thinking of would be appreciated, thanks for the help in advance.

http://www.ls1howto.com/index.php?article=4

Johnny wangwang

Melling 10295 oil pump. Replace front main Seal, Timing chain, Pulley Belts, steering rack bushings, Tire rods....I could go on

Whatever you touch that hasnt been replaced and you can afford your gonna want to replace or upgrade. No point in going in just for a pump.

tommypenguin

Thanks for the reply, from what I've read I don't have to pull steering to do the oil pump, am I mistaken?

Thus far my parts list I have compiled I will need are...

GM DEXCool Premixed 12378390 X3
GM Oil Pump Gasket (O-Ring) 12557752 X2, just in case I cut one
GM Water pump gaskets X2 12559271
GM Balancer Bolt 12557840
ACDelco Main Seal 296-02
ACDelco Water Pump 252-846
Melling Oil Pump 10295

Mike94ZLT1

The starter motor does not turn the crank fast enough to pump oil to the top of the engine.

Yes, you need to pull the steering rack to get the balancer off.

Why not try running it with a mechanical gauge to see what is happening before you go through the trouble of ripping that all apart?

robert1989

People on here will say a bad oil sending unit will not read 0 or will read a certain thing when started. This is a lie. A bad oil sending unit will do what ever it wants. I am speaking from experience.

tommypenguin

Thanks for the feedback guys. I would like to exhaust all troubleshooting I can do prior to tearing down, as this will be my biggest endeavor working on a car. Though I've done quite a bit over the years and am not intimidated by the scale of the job.

I have read of a couple members who were seeing zeros on their oil pressure sending unit (OPS) and it was caused from bad wiring and or/the ecm that it was connected to. I was hoping I could rule that out by my test with the rag and not seeing oil on the new OPS but I will grab a mechanical gauge, start car for 10 seconds and check to see if I'm getting pressure. If I am I will pull out the voltage meter and check pins on the plug and go down further troubleshooting the OPS.

Either way I will follow up with my results. If you guys have any other troubleshooting steps I should exhaust please keep them coming, thanks.

Johnny wangwang

Also, If theres one thing ive learned when it comes to getting some parts for these cars...Felpro and a local shop are your friend. I did GM head gasket, upper oil pan gasket and rear main seal. The OEM water pump came with new gaskets. The rest is felpro or I didnt touch it cause its not leaking or its easy to get to if it does.

DevilMan02

I'm in the same situation except my motor is stock. I've been considering looking around at engine swaps since I know this one had overheating issues, boiled over many times, and warped the head gaskets. God only knows what condition the bottom end is in.

I haven't gotten around to checking the oil pressure sensor, but I replaced it a couple years ago--I'm doubtful barking up that tree will be of any use.

dankhts

I'll bet it's not your oil pressure sending unit, nor the oil pump.... I'd put money on it being a bearing going out..... Cam or main..... You're loosing oil pressure ...... Ask me how I know.....sorry.....

tommypenguin

^^^I hope not but is definitely possible. I ordered a good oil pressure tester gauge from Amazon should be here by Wednesday, hoping I see some pressure on it.

VGLNTE1

I wouldn't run a melling. For some reason they have a great reputation. No idea why. I had a Ls6 ported pump for 7 years on my 416. Was great. I finally lost pressure one day, so here is what I did. First thing you need to do it check the oil for material. Hopefully you have magnetic plug. If not, buy one. If you have alot of metal in there, it's time for a complete tear down. I found that my comp cam was starting to come apart, which isn't abnormal for comp. They make some crap quality cams. After rebuild I talked to katech and they suggested the Ls4 ported pump. Cold starts is 70psi and hot is around 40-50.
If you don't have material in the oil, it's prob the pump. There is no need rotor replace the world. If you have a stock balancer, throw it in a fire. Get an ati. Not a cheap powerbond or slp. Crap. New chain and front seal. Rest is OK. No need to replace tie rods and yadda yadda. Waste of money.

Johnny wangwang

Why do you have no Idea why melling has a great Reputation? Recomending an OEM oil pump that fails all the time is not a Fix IMO. Id run a melling over an OEM oil pump all day.

And replacing anything thats worn is just smart. Replace everything you touch that needs replacing/is worn while your in there! Also upgrade anything you can afford to in that area.


Also, it Sounds to me like the oil pump is dying to me. When bearings get worn the oil pressure is constant low. It doesnt drop to Zero and then come back up. Bad Oil pumps do do that though.

tommypenguin

I don't recall if I have a magnetic oil plug or not, I know I cleaned the drain plug for both oil changes I have done and nothing was on the plug but I did not test to see if it was magnetic. I will this time and replace with a magnetic one if it is not. I'm keeping my current oil in the car given the quality of it until after doing the oil pressure test. Amazon said the gauge should be in tomorrow.

If I have no oil pressure after the test I will drain my oil wand through it with my 50lb magnet stick to see if it picks up anything.

Thanks for the further context regarding if my bearings were going out I would see constantly low oil pressure. I was not aware of that symptom.

I will replace everything that looks worn along the way if it gets to that point. So far I have not found a thread regarding a melling oil pump failure but after read vglante's post I did a search and found a poll regarding oil pumps. Both Katech and Melling appear to be the most renowned oil pumps to use for LS motor in the c5.

https://www.corvetteforum.com/forums...ad-racing.html

Again much appreciated guys for the education and if you have anything new to add keep it coming.

Unless any other troubleshooting steps are mentioned I should attempt before tomorrow I should know soon if the corvette will be getting taken apart or if I lucked out and will be able to troubleshoot ops plug, wiring, ecm. Given I saw oil pressure during my short drive and then saw the needle decline to zero at idle I'm betting it's not OPS at a minimum, if no significant shavings are in the oil after confirming that I should be able to comfortably feel the oil pump is the culprit and begin the tear down.

jp260z

Failure of the o-ring between the pump and pickup tube will create EXACTLY the problem that you are experiencing.......little to no pickup and pumping of oil at low RPMs.

tommypenguin

^^Thanks for the heads up.

I just hooked up my OTC oil pressure tester to the OPS location, started the car for 5 seconds and saw no oil pressure register on the gauge. Next step will be to drain oil and take a look. Regardless, going to have to tear down to identify what the culprit is. Praying I don't see any noticeable amount of shavings when draining the oil and hoping the only issue is the pump and/or o ring.

tommypenguin

I drained the oil and strained it while moving it from container to container, no chunks of metal were in the oil. I do have a magnetic drain bolt and there were some minor flakes on it but nothing that has me alarmed. Tomorrow I'll drain the coolant and hopefully have the supercharger unbolted giving me some room to get the tear down further under way. I'll post back in a while when I've made some significant progress. Any recommendations on what chain to go with? LS2?

VGLNTE1

I believe the part has been updated and they are all the same. Ls7 I think? I use a c5r chain.

jp260z

The latest and greatest is: C7R LS seamless chain from Hinson Motorsports

VGLNTE1

I read about that. It's from hinsen though. Not actually used on the c7r, or other gm race motors. Last time I inquired that is...

tommypenguin

I looked up both chains after your posts, the c7r and c5r chain on amazon both are offered by Hinson. Should I be selecting a different manufacturer of the chain? Links below for reference.


C7R


C5R



Had a good night with the car, got the supercharger pulled, bracket, intake plumbing from IC and filter off. I'm sure it will take triple the time to put back on and get everything to line up correctly.