Spun bearing(s) or failed oil pump?

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VIKING_MECHANIC

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As some of you know, I've been suspecting a fuel issue on my C1500 over the last few weeks. After watching several videos, reading posts on this forum and just reading through the Hanes manual and I could also smell gas in the intake, I decided to replace the pressure regulator.

After about 3 hours, I had it replaced, checked everything and went to start the engine. It ran for about 5 seconds before it died. Each time I would start it, this knock/rattle sound would give progressively louder to the point it would drown out a normal conversation.

Obviously after the third start my focus changed from why it was dying to why it was making a knocking sound. I haven't yet checked the oil pressure manually or checked the oil and filter, but when it was briefly running the gauge was showing 80psi.

Could the pump fail to the point where the sensor can get a good reading but not lubricate the bearing? I know the only way to truly know is to take off the oil Pan and check everything.

This is the intake after I took off the plenum. Notice the yellow varnish, corresponding to the running rich on drivers' side and lean on passenger.
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VIKING_MECHANIC

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Dude that intake is CLEAN. When did you get the truck?
I've had the truck since I was 18 about 12 years now. I had the engine replaced after I bought it because of a rod knock(knocking on wood). I had the intake cleaned after it blew a head gasket back in October.
 

thinger2

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Dont run it anymore.
Pull the oil filter and cut it open and look for chunks and glitter in the filter pleats.
That knock noise could be a misfire or bad timing or just a blown out exhaust gasket.
Or a skipped timing chain or a stuck valve etc.
Dont believe anything you see from the factory gauges.
Dont even consider them in your disgnosis.
They are garbage and they dont mean anything at all.
 

Supercharged111

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Orrr if he got antifreeze in the oil when the head gasket went it could have eaten a bearing and it chose now to rear its head.
 

VIKING_MECHANIC

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Dont run it anymore.
Pull the oil filter and cut it open and look for chunks and glitter in the filter pleats.
That knock noise could be a misfire or bad timing or just a blown out exhaust gasket.
Or a skipped timing chain or a stuck valve etc.
Dont believe anything you see from the factory gauges.
Dont even consider them in your disgnosis.
They are garbage and they dont mean anything at all.
I won't be running it till I figure out what the knock is. I'm planning on draining oil and checking filter and possibly pulling pan if that yields no result.

I don't have a scanner so I can only rule out mechanical problems.
 

VIKING_MECHANIC

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Orrr if he got antifreeze in the oil when the head gasket went it could have eaten a bearing and it chose now to rear its head.
It may be possible but not likely. I flushed the oil twice after the head gasket problem. First time was for 30 minutes and the next was about 300ish miles. But it does have 140K since the rebuild...
 

RichLo

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Pull the valve covers and check all of the rocker arms for looseness. Stuck valve, broken valve, bent/broken pushrod, collapsed lifter, flattened cam lobe. All can be seen by wiggling the rocker arms.
 

VIKING_MECHANIC

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Update: I took the oil pan off to inspect the oil pump and bottom of the rotating assembly and this is what I found.

The pump seems to be okay, but I did notice some gasket material and some sort of plastic or thin metal in the pick-up screen. Also, the pick-up tube is welded to the body of the pump for some reason.

Another thing I noticed is the bottom of all the pistons look brand new, making me think when the head gasket blew and the coolant had time to do all of that, it most likely f**ked some bearings as well. Something else I noticed is, all the connecting rods I could move side-to-side against the crank by roughly 0.5-1mm. I don't know that much about the technical aspects or tolerances of building an engine, but that movement has me concerned and curious if that's the source of the knocking sound. It's particularly noticeable at the front of the crank where #1&2 are.

The oil under a very bright light didn't yield any sparkly bits, but I did notice what seems to be trace amounts of coolant left over. It's not noticeable on the dipstick, but in the drain pain it looks a little milky. Yay...

At this point I'm suspecting a rebuild, but I might take it to a local shop for a second opinion.

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