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oil pressure

Low oil pressure would cause the lifters to collapse, lift rods likely knocked the retaining clips out of their seats.
 
How do the lifter bores look?

Are you dealing with the rare factory machining screw up GM corrected with 0.010 oversize lifter(s)? In other words dropping a standard lifter in a 0.010 oversize bore?

From the 1993 Light Duty Truck Unit Repair manual:
"Some engines will have both standard and 0.010-inch oversize hydraulic lifters. The oversize lifter will have a "10" etched on the side. The block will be stamped "O.S." on the cast pad adjacent to the lifter bore and on the top rail of the cylinder case above the lifter bore
 
Lifters and holes is standard size. When I built this diesel, a few old lifters were broken. I replaced them. After 200 miles, the diesel began to work unevenly. The oil pressure at the operating temperature became low.
Crankshaft is new "Scat". M/R bearing "Clevite"
 
Well, I carefully read the thread http://www.thetruckstop.us/forum/threads/no-oil-pressure-at-idle-after-rebuild-new-block.12296/. Thank you Googl translator! Without you I would read a very long time!
The problem is the same as the diesel I'm repairing now. Well, what are the reasons for the low pressure of hot oil I have understood.
-Large clearances in bearings. It is almost impossible. Large clearances in bearings. It is almost impossible. When assembling, I always check the gaps..
- defective oil pump. May be. I'll test it
- defective bypass valve. I correctly understood that we are talking about the oil pump valve? Or about the oil cooling gallery valve?
- possible oil leakage from different places.
- crack in the block. In this diesel this is possible because in this block the crankshaft crashed three times. But how can I check this?
- broken lifters. It was easy. But I'm starting to think that the lifters broke because of no oil pressure.
 
For the oil pump: when I was building my hotrod engines, I made an adapter plate to test the oil pumps. A flat piece of steel with 3 holes drilled in it. 2 on outside to bolt the plate to the oilpump,and one in the middle the same size as the output port. Then I welded on a female 1/8" npt fitting.
I mounted it to the oilpump, placed it in a vice, and hooked up a gauge. Used a 3/8" highspeed drill to drive the oilpump. Put a bucket with oil in it to the pickup tube and tested for pressure that way.
Hope this helps.

When you checked gaps in bearings, you checked each individual bearing- rods; mains; and most importantly cam bearings?
 
Will L. said:
For the oil pump: when I was building my hotrod engines, I made an adapter plate to test the oil pumps. A flat piece of steel with 3 holes drilled in it. 2 on outside to bolt the plate to the oilpump,and one in the middle the same size as the output port. Then I welded on a female 1/8" npt fitting.
I mounted it to the oilpump, placed it in a vice, and hooked up a gauge. Used a 3/8" highspeed drill to drive the oilpump. Put a bucket with oil in it to the pickup tube and tested for pressure that way.
Hope this helps.

When you checked gaps in bearings, you checked each individual bearing- rods; mains; and most importantly cam bearings?
Click to expand...
No is not all. This block had worn-out planes of the main bearings. I did it low on .0039 and drilled a hole for the crankshaft. Then I checked the clearance only on one crank. After building, the diesel engine run about 300 miles after that it began to shoot the air filter (lifters). After about another 50 miles, the oil pressure began to drop
 
Yeah, you need to check all 18 bearings. One out of tolerance is all it takes.

Then check lifter bores and lifters, test flow oil pump with valve covers off to ensure oil at all 16 rocker arms, and output flow from turbo.

It takes a little more time to do it right, but it is always worth it.
 
Well, I think that it should not to be.
 

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In the oil pan I found pieces of hydraulic lift plates. I think that the events developed like this: the hydraulic lifts broke, then the connecting rods chewed these plates, then the pieces fell into the oil pump and then the pressure began to fall.
 
Replace the Engine Oil Cooler! It's full of the chewed up debris the oil pump spit out and can't be flushed. Best I can tell is oil flow goes to the oil cooler then to the oil filter. The cooler itself may be clogged, but, a bypass would just allow oil to overheat.

oilflow.jpg

Did you disassemble and check the oil pump to know if it was good during the last rebuild? Possible the oil pump simply ate debris from lifter failure(s).
 
If that bypass opens, your fuel pressure should still read and be the same, it just does not filter your oil.

As for the bypass in the pump, you have to build a custom piece to try to test it off the engine.
 
WarWagon said:
How do the lifter bores look?

Are you dealing with the rare factory machining screw up GM corrected with 0.010 oversize lifter(s)? In other words dropping a standard lifter in a 0.010 oversize bore?

From the 1993 Light Duty Truck Unit Repair manual:
"Some engines will have both standard and 0.010-inch oversize hydraulic lifters. The oversize lifter will have a "10" etched on the side. The block will be stamped "O.S." on the cast pad adjacent to the lifter bore and on the top rail of the cylinder case above the lifter bore
Click to expand...
You learned me something new. :)
 
Well I started the diesel. The first 2 minutes he sneezed a little and coughed and smoked white smoke. The exhaust was wet. Then it began to work at idle speed. Oil pressure at operating temperature is normal. Tomorrow I'll start again to see whether it will sneeze again.
 
So the second start. 1 minute strong white smoke and clapping in the exhaust. Then no smoke and the diesel is running smoothly. What could it be?
 
No fire in a cylinder till it comes up to temp? Sounds like it's getting fuel due to the white smoke. Did you smell the smoke to make sure it's diesel not coolant?

Compression test? Sticking open exhaust valve comes to mind.
 
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