Chevy 350 rebuild....LOST oil pressure HELP!!! - Hot Rod Forum : Hotrodders Bulletin Board
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Old 02-18-2005, 03:10 PM
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Chevy 350 rebuild....LOST oil pressure HELP!!!

I started a rebuilt 350 a few days ago, broke it in proper, it had great oil pressure the entire break in and the first few test drives. Today I took it out for a little 20 minute drive at about 55mph and it seemed to gradually lose oil pressure eventually getting hot and losing power. I got it home ok but now it has no oil pressure at idle but the pressure will come up as the engine revs.

Any ideas on where to start looking? It never knocked or ticked like a rod bearing spun! It starts fine just has no pressure at idle.

Bill

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Old 02-18-2005, 04:01 PM
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Oil and Filter

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Originally Posted by wed68
I started a rebuilt 350 a few days ago, broke it in proper, it had great oil pressure the entire break in and the first few test drives. Today I took it out for a little 20 minute drive at about 55mph and it seemed to gradually lose oil pressure eventually getting hot and losing power. I got it home ok but now it has no oil pressure at idle but the pressure will come up as the engine revs.

Any ideas on where to start looking? It never knocked or ticked like a rod bearing spun! It starts fine just has no pressure at idle.

Bill
Did you change the oil and filter after the break-in period? Avoid Fram filters (IMO), use an AC or Wix (Napa or Carquest). Ed
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Old 02-18-2005, 04:07 PM
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Mechanical or electrical gauge? If it is mechanical,does it have the cheap plastic line? If so it may be bent tight and reducing pressure. What is your psi at idle?1000 RPM's? 2000 RPM's?
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Old 02-18-2005, 05:49 PM
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yes I did change the oil after the break in and yes there is an orange filter under the block, could that be it the filter came apart?

The gauge is the stock electric gauge! and the oil pressure at idle reads 0 at 1000 or so it reads about 20 and it contiues to climb as the rpms do but when the rpms level off at any point the oil pressure falls off to 0?

Could the pick up have come loose, screen plugged, filter came apart? why pressure for two days now none?

I will drop the pan tomorrow and look! I just needed some incouragement!

Bill
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Old 02-18-2005, 05:51 PM
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orange filter

Orange filters are Fram. I have put new ones on used engines that lost oil pressure. I refuse to use them anymore. I use an off the shelf filter for break in. Then I use a K&N.
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Old 02-18-2005, 05:51 PM
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I agree the first thing I would do is change the oil and the filter.

Royce
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Old 02-18-2005, 06:13 PM
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If it is a mechanical oil pressure guage you need to bleed the air out of the line.

Are the lifters ticking? Rockers?

Did the block get cleaned well before assembly?
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Old 02-18-2005, 06:25 PM
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I will try the oil change and new quality filter in the morning, yes the block was cleaned at the machine shop after the .030 bore.

No there is no ticking or knocking!

Bill
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Old 02-18-2005, 06:27 PM
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No ticking or knocking is a good sign. Hope all turns out well.
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Old 02-18-2005, 07:34 PM
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did you weld or press on the oil pickup tube
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Old 02-18-2005, 07:50 PM
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I did not weld the pick up tube on, would I have any oil pressure at all if it worked loose?

Bill
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Old 02-18-2005, 07:50 PM
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Pick up a good mechanical oil pressure gauge. You can hook it up and not make a permanent fixture in your car if you need to. You could hook it and mount it under hood to check what it is at idle and with the engine running thru the RPM band. Good mechanical gauges are not expensive and are a direct piece that will read regardless of whether there is a circuit problem going to the electric. Your sender pulls a signal from there it sends it to the circuit board in your dash panel.
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Old 02-19-2005, 08:09 AM
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pull off the rocker cover and see if any oil is pumping through the rockers while motor is running
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Old 02-19-2005, 04:54 PM
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Update! I change the oil today to 10w40 but no change. I did find pieces of what looked like bearings in the oil filter. When I started it cold it had good pressure. I then found an oil leak on my sender unit, I changed it but the same thing little pressure at idle but about 30 psi while driving!



Bearing spun?

Oil pump came apart?





Bill
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Old 02-19-2005, 05:03 PM
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It could be a bearing issue. Did you have a shop press in new cam bearings?
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