5.3 Knocking--Update, found the problem

[diesel4me]

We had some vehicles at the junkyard that had been rolled,most of them still ran,but had suffered some bearing damage from being upside down while still running,long enough to starve them of oil pressure...an EFI vehicle can run upside down longer than you think....maybe you'll get lucky and its just the flex plate or bolts,but I wouldn't be too optomistic...

 

[pvfjr]

The inspection cover on 4L60E went away and now it is a solid bellhousing. There is a little 2" or 3" hole you can uncover to look up there. You will need to remove the starter to get to the the converter bolts. I find that you can disconnect the battery and leave all the connections on the starter in place. Just push it back or hang it from a coat hanger or something. This will save a lot of time since you need to remove and replace the starter twice for this experiment (and you never know when you will break off the little terminals). You can get a prybar in the little hole and turn the engine by the flexplate there.

As you already found, the converter can push back a little into the transmission pump once it's unbolted.

For any noise that could be lube related, make sure there is a decent oil filter in place and not a FRAM. (For Ruining A Motor?)

Thanks, and yeah, I already put a purolator on it.

 

[pvfjr]

We had some vehicles at the junkyard that had been rolled,most of them still ran,but had suffered some bearing damage from being upside down while still running,long enough to starve them of oil pressure...an EFI vehicle can run upside down longer than you think....maybe you'll get lucky and its just the flex plate or bolts,but I wouldn't be too optomistic...

I'm starting to fear this may be the issue. There was dirt all over the headliner, so it may have been upside down for a little while. Who knows how long it ran.

 

[4xcrazy]

Dirt on the headliner,,, yeah,,, not too good.

 

[1BEATK5]

We had some vehicles at the junkyard that had been rolled,most of them still ran,but had suffered some bearing damage from being upside down while still running,long enough to starve them of oil pressure...an EFI vehicle can run upside down longer than you think....maybe you'll get lucky and its just the flex plate or bolts,but I wouldn't be too optomistic...

That's what I was thinking as soon as he said it was rolled.

 

[pvfjr]

I'm gonna pull plug wires one at a time while it's running. If it's a lifter problem like my neighbor swears it is, then that wouldn't be affected right?

If the noise quiets when a wire is pulled, then doesn't if have to be in the bottom end?

 

[diesel4me]

Killing the spark will silence many knocks,like bearings,piston slap,and might actually increase a loose wrist pin knock,but wont affect a lifter tick...it is possible to use a stethascope to pinpoint where the knock comes from better,also if the knock occours at every revolution its the lower end,every other revolution,its a piston or valve train noise..also try pulling and pushing in on the harmonic balancer with the engine OFF and note how far the crank goes in or out,too much end play will make a bad knock that is erratic,similar to loose torque converter bolts or a cracked flex plate..also make sure the pulleys have no cracks in them too..

 

[pvfjr]

Well I pulled the belts off, no change. I disconnected the coil packs one at a time while it was running, and no discernible change. Does that mean that it's not a rod knock?

With the stethoscope, I hear it the loudest at the oil pan, and near the timing cover/water pump area. Two of my neighbors swear it's a lifter, but I don't know what their experience is. I haven't had a lot of bad engines to listen to myself....I'm a Nissan/Subaru guy mostly.

 

[pvfjr]

How do I tell if it's every revolution or every-other? Can you tell from the video? It was idling at about 900-1000 RPM in the vid.

 

[diesel4me]

I cant watch any videos on my computer,so I'm no help there---but you could hook a timing light up to one plug wire and use the flashing strobe to help you tell if its knocking upon every revolution or not....it might be the timing chain,I have seen ones so loose they actually rubbed a hole thru the timing cover ,they make a clicky-ticky noise similar to a bad or stuck lifter....on older V8's with mechanical fuel pumps a worn pump rocker arm or broken spring on it can also mimic a bad lifter...

If the pan will come off without much work,it may pay to just remove it and try moving each rod by hand to see if any of them are sloppy on the crank,indicating a spun or failed rod bearing...

 

[pvfjr]

Well I think I'd have to pull out the front differential, but it may be worth it in the end. Tomorrow is my only chance to swap the motor if necessary before school starts, so I need to figure out quick whether or not this thing is worth working on. If I pull the heads just to troubleshoot, I'm out over $100 in gaskets and bolts to put it back together. If it ends up being a cam bearing, the block may need some work, and that's $$$. If it's a rod bearing, the crank will probably need work, and that's $$$ too. A used engine with warranty is running around $600 here. What do you guys think I should do?

I'm thinking about just pulling the valve covers and oil pan, and seeing what I can figure out. I can at least put those back and drive it across town tomorrow where I have access to a garage for a day. If I pull the heads, then find out I need to swap the motor anyway, it'll be a lot more difficult to transport the truck.

 

[diesel4me]

It's unlikely you'll succeed in pulling the IFS front diff out in a weekend,it would be easier to just unbolt the motor mounts and hoist the engine up enough to get the pan off...or just take it right out,seeing you might end up replacing it anyway...taking it out will take about 2 hours maybe,if all the bolts come out and the exhaust unbolts OK...

If it were me and I had money to buy a used engine,I'd just swap one in,and save the other "knocker" for later teardown and inspection and fix it later on, for a spare or resale..replacing the whole engine will be faster,and its unlikely you'd have much luck getting the knocking one back in running condition in a hurry...

 

[pvfjr]

Well I think I can pull the oil pan without too much effort actually. I pulled the valve covers, and all the push rods seem to be snug. I pushed down on all the rockers, and they don't seem to want to budge. I'm starting to think it's not a valvetrain issue anyway, as I listened to a 5.3 with a lifter issue on youtube, and it sounds a lot slower than mine. I think my noise will be in the bottom end.

I think you're right, in interest of time, I think I'll just swap the motor.

 

[pvfjr]

I pulled that pan, haven't found anything out of place yet. The rods all seem to move side to side on the crank journals, maybe about .010 or so, just a guess. I can't get any of them to jiggle on the crank though, which is somehow disappointing. There just doesn't seem to be any radial play anywhere.

All the cam lobes that I have been able to see so far have looked smooth and shiny, I'm heading back out with a flashlight to see if I can spot a spun lifter or something.

 

[pvfjr]

Here are some pics of the #8 rod. Seems like it's done for. Now the question is how to proceed from here. I think that maybe the cylinder filled with oil, then they tried to start it. I'm still wondering where the noise was coming from though, because I can't jiggle that rod at all. It's nice and tight. The others have about .010" of front to back play, but no radial play on the journal. Maybe I should unbolt the #8 rod cap and see what the bearing looks like? Could a new rod save this engine? I suppose that depends on what the crank looks like, I'll have to check. On another note, from what I could tell from underneath, the cam and lifter rollers appear to be functioning as they should.

 

[y5mgisi]

Yup. They short roded it. Might be able to swap out just that piston/rod, but probably time for a junkyard block or new short block.

 

[1BEATK5]

The noise is the piston "rocking" in the bore because that rod is shorter.

You could put a piston and rod in that hole. I have done it. But it's sometimes a coin flip on longevity. Every time you drive it there will be that question of doubt lingering in the background.




Edit- dang you Mitch! Beat me!

 

[y5mgisi]

Snooze = lose.

 

[pvfjr]

Well money is a little tight after buying the truck, and I still have some other parts to purchase to get the cab in order. If I could get away with swapping some parts into this one, I think I'd like to give it a try and cross my fingers.
Also, this motor is incredibly clean inside. All the lifters seem to be in great shape, as well as the cam, and there is NO crud or sludge ANYWHERE. I couldn't even believe it. It looked brand new under the valve covers and in the pan. I'd hate to go buy another used motor in unknown condition, you know?

So do you think the piston is trashed? It's a shame they can't be loaded from underneath, but at least I only have to pull one head off. I was thinking of replacing the #7 rod bearing for good measure, just in case it's had some unusual stresses on it. The twist in the #8 rod has been putting a bit of side-load on the pair of rod bearings.

If I do need a piston, rod, two rod bearings, head gasket, head bolts, oil-pump o-ring, etc; where is a good place to get those things? I know some of it can be had at the parts store, but I don't know about the rest. Is there a brand or style that I should stay away from?

 

[Russell]

Well money is a little tight after buying the truck, and I still have some other parts to purchase to get the cab in order. If I could get away with swapping some parts into this one, I think I'd like to give it a try and cross my fingers.
Also, this motor is incredibly clean inside. All the lifters seem to be in great shape, as well as the cam, and there is NO crud or sludge ANYWHERE. I couldn't even believe it. It looked brand new under the valve covers and in the pan. I'd hate to go buy another used motor in unknown condition, you know?

So do you think the piston is trashed? It's a shame they can't be loaded from underneath, but at least I only have to pull one head off. I was thinking of replacing the #7 rod bearing for good measure, just in case it's had some unusual stresses on it. The twist in the #8 rod has been putting a bit of side-load on the pair of rod bearings.

If I do need a piston, rod, two rod bearings, head gasket, head bolts, oil-pump o-ring, etc; where is a good place to get those things? I know some of it can be had at the parts store, but I don't know about the rest. Is there a brand or style that I should stay away from?

All these engines are that clean inside if they are properly maintained...

That said, you may find it is cheaper to buy a used short block vs repairing what you've got! Just ran into that with the Duramax engine in my Tahoe. I wound up buying a lower mileage used engine and haven't looked back since.