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Started By
Message
OT mechanics, question
Posted on 3/31/16 at 1:43 pm
Posted on 3/31/16 at 1:43 pm
2010 Silverado, 94000 miles. Recently started reading low oil pressure at hot idle. Pressure is fine when cold. After 15-20 minutes at highway speed, pressure drops on deceleration, and gets very low at idle-I've started throwing it into neutral at stops to keep the RPM's up. No lifter noise, but when pulling into the driveway today, I heard what sounded like knocking. Oil level is full.
Am I looking at a bad oil pump? Bad bearings?
Am I looking at a bad oil pump? Bad bearings?
12
Posted on 3/31/16 at 1:49 pm to Jim Rockford
Bad Scribulator.
Tree fiddy to fix.
Tree fiddy to fix.
Posted on 3/31/16 at 1:51 pm to Jim Rockford
Not a mechanic but I had a very similar situation with a Ford truck a few years ago. Turned out the oil pump was ok but a critter called the oil-sending-unit was dying.
Posted on 3/31/16 at 1:51 pm to Jim Rockford
How quick is it losing oil. Any noticeable leaks?
Also missed full.
Could be pump or something similar.
Also missed full.
Could be pump or something similar.
This post was edited on 3/31/16 at 1:53 pm
Posted on 3/31/16 at 1:51 pm to Jim Rockford
Never mind. Missed where you said it was full.
This post was edited on 3/31/16 at 1:53 pm
Posted on 3/31/16 at 1:57 pm to Rockbrc
quote:
Not a mechanic but I had a very similar situation with a Ford truck a few years ago. Turned out the oil pump was ok but a critter called the oil-sending-unit was dying.
I would go with that, because these things are notorious for having bad oil sending units, but the noise makes me think it's actually starved for oil.
Posted on 3/31/16 at 2:05 pm to Jim Rockford
Sounds like a loose nut between the front seat and the steering wheel... Have you checked the blinker fluid?
Posted on 3/31/16 at 2:08 pm to Jim Rockford
if it's the 5 pernt three then the pickup screen in the pan is stopped up full of carbon. Very common on those model 5 pernt threes.
Posted on 3/31/16 at 2:30 pm to Jim Rockford
Do you hear knocking, or tapping? Very different sounds, and very different prognosis. If it was knocking, you're fricked. Possibly new cam and bearings. Potentially piston rods. If it is tapping, it's the lifters/valves from being starved for oil. If oil pressure drops out to nothing, you should hear tapping much more frequently.
If it's the sending unit, you won't hear anything. All it does is send the info to your dash. The pump pumps the oil to your bearings. If pump screen is clogged it can do that. If pump is going out it can do that. If rod bearings are out, you would hear knocking all the time. It is very possible that pump is clogged/going out, and you starved the bearings causing failure. If so, you will hear knocking if you start it back up.
Short answer is that if you don't want to take it somewhere, change the sending unit. It's very easy to get to and change and is the cheapest and easiest of all. If that solves your problem, be happy. After that, you can find out very easily if it's the bearings by changing your oil. Your oil plug has a magnet on the end of it. If there are metal shavings on it, you're back to the fricked (but not put it in the junkyard fricked) part.
If it's the sending unit, you won't hear anything. All it does is send the info to your dash. The pump pumps the oil to your bearings. If pump screen is clogged it can do that. If pump is going out it can do that. If rod bearings are out, you would hear knocking all the time. It is very possible that pump is clogged/going out, and you starved the bearings causing failure. If so, you will hear knocking if you start it back up.
Short answer is that if you don't want to take it somewhere, change the sending unit. It's very easy to get to and change and is the cheapest and easiest of all. If that solves your problem, be happy. After that, you can find out very easily if it's the bearings by changing your oil. Your oil plug has a magnet on the end of it. If there are metal shavings on it, you're back to the fricked (but not put it in the junkyard fricked) part.
Posted on 3/31/16 at 2:30 pm to meauxjeaux2
MJ2... I haven't torn down anything made in this century. Does that 5.3 still have a conventional oil pump or is it a georotor driven by the crank?
Posted on 3/31/16 at 2:33 pm to Jim Rockford
I doubt it's a sending unit. More than likely to be something with the pump or pickup tube.
Posted on 3/31/16 at 2:34 pm to Fratigerguy
quote:
Do you hear knocking, or tapping? Very different sounds, and very different prognosis. If it was knocking, you're fricked. Possibly new cam and bearings. Potentially piston rods. If it is tapping, it's the lifters/valves from being starved for oil. If oil pressure drops out to nothing, you should hear tapping much more frequently.
If it's the sending unit, you won't hear anything. All it does is send the info to your dash. The pump pumps the oil to your bearings. If pump screen is clogged it can do that. If pump is going out it can do that. If rod bearings are out, you would hear knocking all the time. It is very possible that pump is clogged/going out, and you starved the bearings causing failure. If so, you will hear knocking if you start it back up.
Short answer is that if you don't want to take it somewhere, change the sending unit. It's very easy to get to and change and is the cheapest and easiest of all. If that solves your problem, be happy. After that, you can find out very easily if it's the bearings by changing your oil. Your oil plug has a magnet on the end of it. If there are metal shavings on it, you're back to the fricked (but not put it in the junkyard fricked) part.
Yeah, cranked it again, and there's a pronounced knocking. Could be tapping, but I know what a lifter sounds like, and it doesn't sound like that. I guess I'm fricked. Don't want to drive it to the shop, so I called for them to tow it in.
Funny thing, the oil pressure was still fine when I started it up cold just now. I guess I did the damage driving it around earlier. Oh well. Looks like I'll have a decision to make, depending on how bad it is.
Posted on 3/31/16 at 2:40 pm to Jim Rockford
Ouch. If it just started knocking, you may be able to salvage the cam and the rods. If so, it's just the rod bearings and they can be changed out pretty easily. But you will have to mic the cam and rods to tell. I wouldn't recommend that if you've never done an engine rebuild.
You can find good low mileage motors at the junkyard. You should be able to find something in the $1500 range pretty easily...possibly much less. New or rebuilt they can be had for around $2000 if you do your homework and aren't afraid of a road trip. But realistically you should be able to have that one rebuilt for much cheaper than the cost of a motor and having someone put it in.
You can find good low mileage motors at the junkyard. You should be able to find something in the $1500 range pretty easily...possibly much less. New or rebuilt they can be had for around $2000 if you do your homework and aren't afraid of a road trip. But realistically you should be able to have that one rebuilt for much cheaper than the cost of a motor and having someone put it in.
Posted on 3/31/16 at 2:42 pm to Fratigerguy
Still have the oil pressure problem, though. I don't want to sink a lot of money into fixing this just to trash it again.
Posted on 3/31/16 at 2:50 pm to Jim Rockford
Yeah but I'm not sure what your point is with that. A new motor will come complete with new oil pump and all that nonsense. If you are having it rebuilt, they will change the oil pump. Your bearings have come apart and there will be metal in the pump.
Posted on 3/31/16 at 2:53 pm to Jim Rockford
How low does it get?
Posted on 3/31/16 at 2:57 pm to Jim Rockford
quote:motor is not ruined bro because it's knocking. You more than likely have the bad oil pickup o-ring issue.Change out this o-ring and the noise more than not will go away.
Jim Rockford
Posted on 3/31/16 at 2:58 pm to eitek1
quote:
Does that 5.3 still have a conventional oil pump or is it a georotor driven by the crank?
Posted on 3/31/16 at 2:58 pm to meauxjeaux2
sounds like you may need a new Johnson Rod.
Posted on 3/31/16 at 3:10 pm to Jim Rockford
The knocking is bad, especially since you've been noting engine oil pressure fluctuations. The fact the these oil pressure drops come at set times and change with your engine RPMs tells me the problem is not with the sender but instead is a real oil pressure problem. If the sender was going bad, you'd see these changes in the oil pressure gauge at random times.
Sounds like you've got a bad oil pump and now on top of that , you've also engine damage from oil starvation.
Sounds like you've got a bad oil pump and now on top of that , you've also engine damage from oil starvation.
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