Thread: SBC no oil pressure at idle!

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I recently blew my 454 big block and swapped it out for a lil 350 with a mild cam. When we got the motor it had been sitting for 2yrs still attached to the shipping crate and covered with plastic. I had the cam pulled and put a bigger cam in and some head work.

I've ran the motor 6000 miles now with very lil issues. I store my truck every winter and today came the day to store it. The truck had already been sitting for 5 months because I was gone for a while. I started it up letting it idle for a good 45 min when it sounded like the lifter collapsed, which I found hard to believe. My oil pressure gauge was at 0, so I shut it down. I used a manual gauge to check it and I still had 0 psi at idle. I Rev'd the engine and the pressure shot up to around 45.

I pulled the distributor and turned the pump with a drill using an old distributor shaft. The pump turned freely and the gauge never moved, I didn't figure it would. I took the gauge out leaving the hole open and turned the pump with the drill, oil cam out in a steady stream.

Im stumped on why a new engine with 6000 miles has now lost oil pressure.

I came to these lil conclusions. Possible spun bearing from sitting for 2yrs and then the installation of a different cam. Maybe it spun just enough at first start up and now it spun more.

Change the oil and filter and try it again, then if it repeats move to the next step. Are you using something like a 10w 30?

Running mobil 10W30

When changing the oil, cut the filter open and check for metal shavings.

Does it still sound like it has a bad lifter?

still sounds like some bad lifters. Start it up and its fairly quiet then it starts to clack up top like a lifter. Rev it up a bit the gauge goes up and after a while the clack goes away like it got enough oil. Let it idle again and the clack comes back. When you hold the RPMS up there is no nock at all, I had a big block blow some lower bearings and it sounded like a diesel when you put some rpms to it.

The relief valve may be sticking. I had an IHC that did the same thing. Changed to a synthetic oil, and it started working! I was sure I was wasting my money, but my fuel and oil dealer said he'd pay for it if it didn't work. Never was a believer in synthetics, but it did work!

Where exactly is the relief valve.

Relife valve is under the filter when you remove the filter you see the part it screws on to I beleave there are 3 bolts that hold it in Its been awhile since I had one apart if you run the pump with out the distributor in You won't show o/p.

Cam Bearings.

change the oil pump had a spring go bad in one . It was a 400 sbc with a high pressure pump.

the pressure reg. valve is stuck wide open in the oil pump. replace the pump or free the pressure reg. piston up in the pump. it might brake loose by changing oil, but i doubt it. been there done that.

thanks everyone. Im going to rip the motor out over winter, might as well do while its in winter storage.

how free should the oil pump shaft spin when turing it with a drill. When I 1st primed the motor it caught hard and slowed the drill right down. Now it turns very free..

I guess the pump going out at 6000 miles is better then down the road.

Also whats this talk about springs in the pump and the pressure reg valve.. can anyone tell me how to check these when I pull the pump.

Originally Posted by Northwoods21

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how free should the oil pump shaft spin when turing it with a drill. When I 1st primed the motor it caught hard and slowed the drill right down. Now it turns very free..

I.

Sounds like something is broken in the pump.

Thats what im starting to think, its still pushing oil up, I pulled the sensor and oil came out in a nice stream.

So I either have a very weak pump and its not pushing enough, or the press reg valve is stuck and im not getting and pressure to build.