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Discussion Starter #1
So my 5.3 vortec dropped oil pressure to 0 put new oil pump timing chain pick up tube oring it was really gunked up so cleaned all that put new sending unit in with screen started it up it went up to 60pounds then after driving it 15 or 20 miles it goes to 0 I took off intake and valve covers they were gunked up really bad so I cleaned them really good got all cleaned back up let some deisel sit in pan for two days drained it did about 5 oil flushes with some sea foam started it up again after all that and new gaskets up top it jumped to 60 after about 30 min on 0 again it's not smoking or knocking
 

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Discussion Starter #3
Did you try a new filter?
I was running a wix filter before I put all the new parts in but as I have been using cheap oil and cheap filter to flush it every time I put some deisel or seafoam in let it idiel for awhile then drain put new cheap filter on it
 

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If you have any ideas please help
All that gunk is usually a sign of using conventional oil rather than synthetic. The conventional oil will mix with moisture causing the sludge to build.
You could have some sludge in the line to the filter, maybe some air blown into the filter mount might clean it out.
I'd try a new sensor next and again, clean up the area around the sensor, including the screen (which I think is between the filter and the sensor).
 

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Does anyone have any ideas what's going on with this truck
Tony, I know your new; but that isn't going to stop me from beating up on you.
Two days ago, I suggested you change the pressure sensor and clean, or replace the screen (you may not have a screen, I don't think they were used in '04), have you done this?

GM oil pressure sensors fail at a very high rate.
I asked if you tried a new filter and you said yes; the new filter is the first step, if that doesn't work you probably need a sensor.
 

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Discussion Starter #12
Tony, I know your new; but that isn't going to stop me from beating up on you.
Two days ago, I suggested you change the pressure sensor and clean, or replace the screen (you may not have a screen, I don't think they were used in '04), have you done this?

GM oil pressure sensors fail at a very high rate.
I asked if you tried a new filter and you said yes; the new filter is the first step, if that doesn't work you probably need a sensor.
Lol that was first thing I did
 

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Ray, he did say he changed the sensor and screen in his first post. Tony, maybe try a mechanical gauge to verify low pressure. What weight oil are you using?
 

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Discussion Starter #15
Ray, he did say he changed the sensor and screen in his first post. Tony, maybe try a mechanical gauge to verify low pressure. What weight oil are you using?
us
Ray, he did say he changed the sensor and screen in his first post. Tony, maybe try a mechanical gauge to verify low pressure. What weight oil are you using?
Using 5w30 and I could hook a gauge up but when it drops to zero you can hear it clattering
 

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Ok, yes you did say you changed the sender in the 1st post and I guess I forgot, or missed it.
Silver thanks.
Tony, you just posted that when the pressure drops the engine chatters, in your first post you said "not smoking or knocking".
Does it now chatter when the pressure drops?
Tony, that's a different ball game.

Low pressure no noise means the pressure is good, the reporting is bad
However, low pressure and noise usually means low pressure.
You changed the pump and you still have the problem
You must have a plugged passage way.
 

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Discussion Starter #17
Ok, yes you did say you changed the sender in the 1st post and I guess I forgot, or missed it.
Silver thanks.
Tony, you just posted that when the pressure drops the engine chatters, in your first post you said "not smoking or knocking".
Does it now chatter when the pressure drops?
Tony, that's a different ball game.

Low pressure no noise means the pressure is good, the reporting is bad
However, low pressure and noise usually means low pressure.
You changed the pump and you still have the problem
You must have a plugged passage way.
The motor doesn't smoke not even start it and it doesn't knock but when it drops to zero the lifters are rattling
 

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Discussion Starter #18
The motor doesn't smoke not even start it and it doesn't knock but when it drops to zero the lifters are rattling
Some one said if I changed everything and it starts and pressure jumps up to 60 then after it warms up drops to zero probably the cam or main baerings
 

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Which means the pressure is really dropping to zero

Edit
Ok, you posted after I posted, which is ok, just saying the above answers one post this will answer the 2nd post.

Your right about if pressure always drops to zero when warm there is probably significant wear. However, your using synthetic oil, it flows very easily and should show about the same pressure warm or cold.

You need to connect a mechanical pressure gauge and see what it reads.

I think your problem is due to plugged passages.
 
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