engine knock no oil pressure need help asap please

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rayninglead

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Ok well after further investigation there's fine metal shavings on the dip stick so there is metal in the pan had 40psi when I started it this morning let it run until reaching operating temp and stayed at about 12psi at idle. The knock it's very quiet but definitely from bottom end no check engine light either which I thought it would be on? Don't know where to go from here because my uncle works at the junk yard and said he can get me a complete 350 vortec with less than 100k on it for 550$ should I just get the new motor or further examine mine and see if it's something worth fixing?

---------- Post added at 06:28 PM ---------- Previous post was at 06:26 PM ----------

And if I try the heavier weight to slow it down how long could I expect it to last sunlit?
 

undy

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Expect $1000+ for a complete rebuild. How many miles on the engine/Yukon? Are you planning on keeping it for quite a while? If so, rebuild what you have. If you're going to get rid of it then get a used engine.
 

SunlitComet

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If you are up to it and the engine seems to stay where it is damage wise for now undo one spark plug at a time. If the knock go away then likely you just have a single rod bearing that went out. It would knock at the rate of a one cylinder per2 rev. or the rate of monitoring one plug going off. If it is knocking faster then the crank bearing may be bad? There is always a possibility that you can use an over size bearing with out the need to regrind but that depends on how much and type of debris there is. Got pics of the shavings, damage?

---------- Post added at 04:53 PM ---------- Previous post was at 04:52 PM ----------

Oh and based on your psi readings in hot and cold plus shavings it is definitely a bearing issue.
 
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rayninglead

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183000 I just bought it 3 weeks ago planned on keeping it for a couple of years at least. Was thinking about getting a used one for now while I'm rebuilding the original. Cause it's my only ride and I start college tomorrow I need it back asap. pulling the motor and dropping in a used one I can do in a day rebuilding one not so much...

---------- Post added at 08:01 PM ---------- Previous post was at 07:57 PM ----------

I'll try pulling the plugs tomorrow after school to see what cylinder it is or to help tell if it's the bearing. What should my oil psi be when hot and cold?

---------- Post added at 08:04 PM ---------- Previous post was at 08:01 PM ----------

I'll take pics tomorrow to if I can figure out how to post them should I drop pan or just drain oil and check it out it looks like fine sand on the dipstick used magnet to be positive
 

SunlitComet

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For example mine has 273,000+ on the original block and when cold idle pressure is at 45psi+ when hot it hovers about maybe 23+. As you can see my bearing are getting a bit old.
 
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rayninglead

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Wow wished I would have known this before I bought it lol it's had 12 psi at warm idle since I've bought it.shame on me I guess. it's rust free and everything works so I guess I'm just gonna get a new motor from the yard tomorrow and drop it in this weekend thanks everyone again
 

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