I have a 96 Vette with 115k miles. I just replaced 2 lifters last week, and adjusted all of the valves. The engine ran smoothly for the first few days. Just recently, the Oil Pressure PSI is shown really low at idle, it's low enough for the check gauge light to come on. Also, the check engine light shows code P0507 "Idle Control System RPM Higher Than Expected"; however, the RPM gauge is showing 800 rpm at idle and functioning very normal. I just changed oil and filter this morning, but this didn't fix the problem. Please help me to fix this problem, is it because I adjusted the valves wrong? Thank you very much!

What is "really low" as far as your psi, both cold and at running temp?

I really can't speak for your case, but 'generally' low oil pressure is a symptom of a spin rod bearing, spun main bearing, or a failing oil pump.

Quote:
I'm not familiar with your '96, but an 800 rpm idle, warmed up sounds high to me. Is this what it has always been? Could you forgot or miss-connected something resulting in a minor vacuum leak?

Oil pressure is the result of resistance to flow. Either the resistance has been reduced as in a spun bearing or some other loss of resistance in the oil system (too much clearance for a new lifter?) or the flow has been compromised. You didn't possibly drop something into the engine that could be partially blocking the oil pick up, did you?

RACE ON!!!

As a rule of thumb, an SBC runs fine with 10psi per 1000 RPM.

I agree with CFI, 800 RPM seems high. I would check for a vacuum leak. There are enough little hoses to cause this. Check the manifold for a broken or disconnected hose.

Before you go any farther into this mess, get a mechanical oil pressure gauge and be sure the pressure IS low.

Also, the oil pressure gauge on the dash will read 80 PSI when the sensor has failed.

I would be worried that any engine with a lifter problem at 115k might have deeper woes. What caused the lifter failure in the first place? The OEM SBC lifter is a rather durable part. I don't know why it would fail, except for neglect, of course.

It low to the shaded area....and enough for the the check gauges light to come on. It shown normal (in the middle) when the engine is cold, but getting lower as the engine get hotter.

you need a manual gauge on there - ASAP.

Quote:


I agree that this has always been the rule-of-thumb and is perfectly acceptable.

However, I've never had any sbc or sbf for that matter that was less than 20-22 lbs of pressure on a mechanical gauge at operating temperature idle.

Quote:

I will reiterate... the dash gauge is junk. It's a general idea, but that's it.

You need to attached a real mechanical oil pressure gauge to the engine and see what is what.

I am wondering if one of your new lifters is a misfit, or, if another lifter has failed.

Which leads me to suspect the entire engines internals, really.

What is the history of this engine? Was it raced? Was it neglected?

Quote:

Well, it doesn't mean you should get 10psi at 1000 or 40psi at 4000, the rule is you add 10 psi to the idle psi for every additional 1000rpm.

Thank you for your useful response. If the symptom is a spin rod bearing, spun main bearing. Can I fix this problem by removing the oil pan or do have to remove the whole engine out of the vehicle beforehand? Thanks for your help.

Have you put a mechanical gauge on the engine yet? You are making a huge leap of faith without all the info.

Technically, you can repair a spun bearing without removing the engine, but I wouldn't do it. You don't know the condition of the journal it's attached to.

My vehicle is showing low oil pressure, and the symptoms are spin rod bearing, spun main bearing. Can I fix this problem from underneath the vehicle by removing the oil pan, or should I remove the engine off of the vehicle, and is it cheaper fix the problem or replace it with a different used engine which only cost me around $800? Thank you very much

You already have a thread discussing this. I am merging them.

Now that that is done, I can elaborate.

You can inspect the bearings by dropping the pan. But I still think a test of the oil pressure is still a good idea.

Also, what do you know of this used $800 engine?

He's all your's Andy.

Dear Bogus,
I already determined the problem that caused losing oil pressure and increase rpm.It is the spun main bearing.
Since I have limited knowledge in the mechanical field. Would you help me identifying all the parts that I'd need to replace to fix this problem? Also, can I fix the problem while from underneath the car by removing the oil pan, or should the engine be removed beforehand? Please provide as much information as you can.
Sincerely,

You really need to pull the engine and rebuild the bottom end. Check Summitracing for an entire bottom end kit. If this isn't your thing, then farm it out. You could still pull the motor yourself to save money. Mechanics prefer to order the parts themselves though than put in something you bought off the internet. It's an LT1, but don't fall for the Corvette tax, there's nothing exotic about this engine. Tell the shop it's a Camaro motor!

Pull engine. Disassemble engine. Drop off block, crank, rods, flywheel/flexplate, and balancer. They will check the block mains to see if it needs to be line bored. If so you will need special bearings. They will check the rods, repair or replace them, get new bearings, and they will check the crack to see if it can be turned or if you need to use it as a core towards a new one. Then have them balance everything. Reassemble using new gaskets, maybe replace oil pump. Would also be a good time to check for cylinder wall wear and maybe bore it to a 355, use new pistons in the rebuild, and maybe even bump your compression a little bit...if the computer will handle all that. Just saying.

Ok... Where to begin.

There are two distinctively different sets of tools needed to build an engine. One set you can buy at Sears. The other set requires experience, practice and an innate understanding of how things work.

From what I am reading here, you are deficient in tool set #2.

I can rebuild an engine. I have even done it a couple of times... however, I cannot do heart surgery, so I defer to experts.

There are books on engine building. You can expect any book worth its salt to be about 250 pages. So typing instructions here just isn't going to happen.

Do this right. Yank the engine and take it to a professional for a correct rebuild. If you nickel and dime this, you will regret it.

" How to Rebuild SBC Chevy LT1/LT4 Engines" by Mike Mavrigian, HP Books

But, like Andy said.

Most guys use a book like this for reference and already have some knowledge.