2003 Chevy 5.3 Knocking

[151Viper]

Here is my latest damn problem. Maybe someone has an idea.

Here are the circumstances that lead to my truck knocking. The truck has been sitting for month and after work today I started it and put it in the garage. It is currently about -5 degree F outside. I had to boost it but it started and ran smooth. Pulled it in the garage and disconnected the neg terminal of the battery and put the battery on the charger. Proceeded to weld a gooseneck hitch onto the rear frame rails all in a 60 degree garage. This all took about 4 hours time. Upon completion of my hitch install I unhooked that charger and connected the battery back up so I could pull the truck outside. When I started it there is a fairly loud knocking sound coming from the under the hood. I shut it down immediately. The sound sounded like there was something caught in the fan so I checked out the front of the engine but that all looked fine. I started it up again with the hood up and it sounded like it was coming from the driver side valvetrain and the engine was missing. Does anyone have any ideas what this might be???? Could it be a broken valve spring??? It has 106,000 miles on it and I changed the oil about 500 miles ago. The truck only gets driven about once a month if that matters. Thanks for any help.

 

[SNOW JW]

I have the same year and 5.3L

I would see if you can prime the oil system maybe unplug the spark plugs??? Some guys talked about piston slap when cold but I never had those porblems.

It would be very rare to see a 5.3 go down this motor is rock solid for the most part.

 

[151Viper]

I have the same thoughts about the 5.3 being a solid engine. I forgot to mention that the oil pressure was sitting at about 40 when it was idling. I am confused why it did not do it when I initially started it tonight.

 

[AKSNOWRIDER]

I have the same thoughts about the 5.3 being a solid engine. I forgot to mention that the oil pressure was sitting at about 40 when it was idling. I am confused why it did not do it when I initially started it tonight.

sounds like a lifter bled down...as long as the oil level is good and it has pressue on the guage(over 15 pds) fire it up and let it run..it should pump back up..if not you might have to replace a lifter.....

 

[knightkrawler00]

I'm putting my money on a valve spring. While it's not common, I wouldn't be surprised to see one roll into my bay today. There is a bulletin out from GM on valvetrain noises on these engines. Broken valve springs, worn cam lobes, sticking valves, leaking valves, and collapsed Acive Fuel Mangement lifters. A leaking or sticking valve or a worn cam lobe shoudn't happen all at once. That year was not equipped with Active Fuel Management, so you don't have those lifters. I've seen enough broken valve springs to go ahead and pull the valve cover whenever I get a truck with your symptoms. I'd start there, you can have the valve cover off in 30 minutes easy. Take a real close look at each spring, breaks can be hard to see sometimes. You can also pull the rockers off, there's no adjustment when they go back on, and see if the tops of the valves are all level. Give them all a push down with your hand, it should be very difficult to move them at all. Good Luck.

 

[mark]

Sounds like a broken spring or collapsed lifter. Check the compression to find out wich one it is.

 

[seanc]

just had a suburban come in with the same exact problem. my guess is the intake gasket blew, diluting the oil with coolant and in turn causing a lifter to collapse.

 

[Nikolai]

I'm putting my money on a valve spring. While it's not common, I wouldn't be surprised to see one roll into my bay today. There is a bulletin out from GM on valvetrain noises on these engines. Broken valve springs, worn cam lobes, sticking valves, leaking valves, and collapsed Acive Fuel Mangement lifters. A leaking or sticking valve or a worn cam lobe shoudn't happen all at once. That year was not equipped with Active Fuel Management, so you don't have those lifters. I've seen enough broken valve springs to go ahead and pull the valve cover whenever I get a truck with your symptoms. I'd start there, you can have the valve cover off in 30 minutes easy. Take a real close look at each spring, breaks can be hard to see sometimes. You can also pull the rockers off, there's no adjustment when they go back on, and see if the tops of the valves are all level. Give them all a push down with your hand, it should be very difficult to move them at all. Good Luck.

I have a 2008 chevy 1500 with Active Fuel Management. Are the AFM motors having issues? What are they?

 

[151Viper]

I'm putting my money on a valve spring. While it's not common, I wouldn't be surprised to see one roll into my bay today. There is a bulletin out from GM on valvetrain noises on these engines. Broken valve springs, worn cam lobes, sticking valves, leaking valves, and collapsed Acive Fuel Mangement lifters. A leaking or sticking valve or a worn cam lobe shoudn't happen all at once. That year was not equipped with Active Fuel Management, so you don't have those lifters. I've seen enough broken valve springs to go ahead and pull the valve cover whenever I get a truck with your symptoms. I'd start there, you can have the valve cover off in 30 minutes easy. Take a real close look at each spring, breaks can be hard to see sometimes. You can also pull the rockers off, there's no adjustment when they go back on, and see if the tops of the valves are all level. Give them all a push down with your hand, it should be very difficult to move them at all. Good Luck.

This is my plan tomorrow. This afternoon I started it and let it idle for about 10 minutes and the sound never went away. Is it possible to change the valve springs without taking the head off?

 

[badapple]

Yes. You need to pressurize the cylinder w/air. Use a compression checker hooked up to a compressor. That will hold the valve in place wile you compress the spring, remove the keeper's and replace the spring. Good luck

 

[151Viper]

Yes. You need to pressurize the cylinder w/air. Use a compression checker hooked up to a compressor. That will hold the valve in place wile you compress the spring, remove the keeper's and replace the spring. Good luck

Would a cylinder leakage tester work? How many psi are needed?? I am going to take the valve cover off this afternoon and check it out.

 

[151Viper]

Well there is a hole in the side of my block the side of my fist. Where is the best place to pick up a long block?

 

[knightkrawler00]

I have a 2008 chevy 1500 with Active Fuel Management. Are the AFM motors having issues? What are they?

Engineering is evaluating new style lifters right now, the AFM lifters can tick on a cold start and GM is trying to make that go away. I've seen a couple of broken lifters, but that's it. There is really very few problems with the AFM setup, I got to preview the system before it came out in the trucks and it looked well thought out and executed. Still, I'm a bit surprised to see so few failures on something like this. I would have no problems driving a truck with the AFM, in fact my next truck will have it.

Well there is a hole in the side of my block the side of my fist. Where is the best place to pick up a long block?

Well, that sucks. I presonally haven't seen a new generation V8 self destruct like that without some external help.

I wouldn't go for anything but factory, except maybe for a good used engine. I've seen too many problems with aftermarket reman's. There are some good ones out there, but none that can come close to a GM reman. Call a few dealers, you should be able to find one that will sell for a couple hundred over list. Large dealers are more likely to sell that low because they'll buy a train car load of engines for a huge discount and can then make a profit selling lower than normal list.

When you do the install it may not be a bad idea to put a new intake manifold on it. There have been a few catastrophic failures that ended up with metal in the intake manifold which then ended up in the new engine. Take a good look at your old one if you are going to reuse it.

 

[JDKZRT]

Well there is a hole in the side of my block the side of my fist.

Thrown rod???
I had an idea where this might be going when you said 'battery charger' and 'welding for 4 hrs'
I'd be curious to know what you find if you pull the engine and remove the main and con rod bearing caps.
Hope I'm all wrong.

 

[151Viper]

$7,500.00 installed. Not a bad price from the local Chevy dealer. Too bas it is a 7,000.00 truck. $2250 for a reman from a local macine shop for just the engine.

 

[151Viper]

Thrown rod???
I had an idea where this might be going when you said 'battery charger' and 'welding for 4 hrs'
I'd be curious to know what you find if you pull the engine and remove the main and con rod bearing caps.
Hope I'm all wrong.

Do you think there was some arcing in the bearings when I was welding?? I thought I would be safe disconnecting the neg terminal?? Would the battery charger come into play?


I am going to wait a few days and see what options come up before I tear it down. I will let you know what I find though. The hole is where the dipstick enters the block. It also knocked out a big chunk of the oil pan(aluminum). I can't see anything out of the ordinary from below as of now.

 

[skidooer1]

try http://car-part.com to see if you can find any good take outs. matt

 

[Zoomer]

I work at Don Wilhelm Inc. in the parts dept and would like to get you the best price possible. Give me a call at 1-800-450-2950 or email me at jeffkummer@hotmail.com with your VIN #

 

[knightkrawler00]

My understanding of welding and bearings is that as long as the ground path is not through the bearings, then there shouldn't be a problem. I'm not much of a welder so please correct me if I'm wrong here.

Also, I've seen plenty of trucks that have been welded on that didn't hurt bearings and hurt bearings won't always break the connecting rod. That 5.3 does have powdered metal connecting rods, so maybe there is something to that? Those rods can be ruined pretty quick if you don't take special care with them. They can't be scribed or punched and should be replaced if dropped. I had to buy a couple that hit the floor doing a rebuild on a 4.2L. I'm interested to see what the bearings, crank, and broken rod look like.

 

[151Viper]

I pulled the engine today. Here is the damage. I am going to get the pan off and check it our better next week when I get my engine stand out of storage.