engine trouble, oil pressure diving

screeminDemon

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Hoping for some suggestions and I appreciate it. My 360 engine (stock compression but lumpy cam, stock 360 heads with double springs, edelbrock intake and 800 thermoquat carb) started ticking and would go away and return at times and now pretty much constant after warm up, now including spike drops in oil pressure. Oil pressure would previously be 40-60 when cruising and is now 20-25 with random spikes down to 5 or even 0 for a sec.
The engine was rebuilt in 2012 and has 30-35k on it.

Thanks for your help!
Doug
 

Bewy

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You might get lucky & have a blocked oil filter, but what would cause it to block up?

If a new filter doesn't fix it [ & I doubt it will ], engine needs to come apart.
 

Phreakish

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Mechanical or electric gauge?
Auto or manual trans?

First, I'd check oil level, then filter.
Next, I'd pull the valve covers and check the rockers for preload/lash and look for signs of abnormal wear.
Then I'd probably pull the intake to check the lifters.

The only things that cause sudden drops in pressure are low level, a bad gauge, or some sort of blockage.

It's also possible for lifters to cause oiling issues, and could be anything from a lifter that fell apart to one which is about to fall out of the bore..

It's also possible for the crank or cam to contribute to pressure loss, but these are rare.
 

Professor Fate

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Mechanical or electric gauge?
Auto or manual trans?

First, I'd check oil level, then filter.
Next, I'd pull the valve covers and check the rockers for preload/lash and look for signs of abnormal wear.
Then I'd probably pull the intake to check the lifters.

The only things that cause sudden drops in pressure are low level, a bad gauge, or some sort of blockage.

It's also possible for lifters to cause oiling issues, and could be anything from a lifter that fell apart to one which is about to fall out of the bore..

It's also possible for the crank or cam to contribute to pressure loss, but these are rare.
That's the first thing that popped into my head- something in the valvetrain may be coming apart.
Check your rockers and then the lifters. I've seen a pushrod punch through a rocker and cause something very similar as the lifter tries to climb out of it's bore.
 

Kendog 170

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I have seen pick up tube on oil pumps get blocked have those symptoms. Some replace the oil pump and don't realize the pick is full of bits of valve stem seals. When I rebuilt my 68 340 it seemed fine but after a couple hard whacks on the bench it sounded like a baby's rattle.
 

Oldmanmopar

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30 - 35k? Here is what I would check first. Thrust bearing, Pull the damper front and then push it back, See what play you have in the crank thrust bearing. A tight converter with a larger cam will wear the thrust bearing,

Check the lift on the cam at the rockers for worn cam lobes. Could be a hole in lifter. an engine with 35k that developes and issue would more then likely be a worn part.

A cheap filter would also contribute to pressure drop due to bad construction of the drain back valve Fram and STP are noted for this, I use only NAPA Gold or WIX. Nothing else
 

gzig5

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Before I put my car into storage the fall after I got it, I put a can of Rislone in it and put some miles on and then parked it in the warehouse for the winter. Next spring all was well driving it home from storage until I was about 1/2 mile from home and the oil light came on and the pressure gage took a dive. It seemed to recover but was much lower pressure than normal. Oil level was fine but it needed to be changed for the new season and to get rid of the Rislone crud. New Wix filter and oil and all was well. Pressure was back to normal if not higher than it had been, maybe due to fresh oil. Only thing I could come up with is that the Fram filter got clogged up with crud after the long soak Rislone treatment. I never thought to cut it open but I'm 99% sure that's what it was. The inside of the motor was squeaky clean, very little to no gunk/carbon left in the top end and the pan was very clean as well. So moral of the story is don't forget about the filter and use good ones. I'd suggest changing the filter and cut it open to see if you've got metal, check the drain pan too. You could have a bearing going away and an oil analysis will verify that if you can't read the drained oil. I used to use Blackstone Labs for my BMW M5 before I sold it.
 

screeminDemon

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Thanks for all the help! You guys have given me some direction and things to get started checking. Thank-you!

The car is a 4 speed and the oil pressure guage is mechanical (oil line to the gage).
Oil level is full/normal.
I pulled the valve cover on the passenger side where the ticking has gotten loud. Nothing visably wrong. However there is one rocker that can be pushed 1/2 inch with my fingers while the others that can be moved (some cannot move due to valve engagement) only go about 1/4 inch.
This seem suspicious.
 

Bewy

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Might have bent a p'rod, pushed the lifter out of it's bore=low oil pressure.
 

krazykuda

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Hoping for some suggestions and I appreciate it. My 360 engine (stock compression but lumpy cam, stock 360 heads with double springs, edelbrock intake and 800 thermoquat carb) started ticking and would go away and return at times and now pretty much constant after warm up, now including spike drops in oil pressure. Oil pressure would previously be 40-60 when cruising and is now 20-25 with random spikes down to 5 or even 0 for a sec.
The engine was rebuilt in 2012 and has 30-35k on it.

Thanks for your help!
Doug

Have you checked to make sure that the oil galley cup plugs are installed that go behind the camshaft thrust plate??? I had a similar problem like this once before and that was the cause, the machine shop didn't put the cup plugs in the oil galleys behind the thrust plate...
 

Kendog 170

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Have you checked to make sure that the oil galley cup plugs are installed that go behind the camshaft thrust plate??? I had a similar problem like this once before and that was the cause, the machine shop didn't put the cup plugs in the oil galleys behind the thrust plate...
Happened to me. I built a 360 LA. Motor would not pump up on left side.. Took out plug I installed and found one someone knocked it in about an inch. Luckily did not hurt motor.
 
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