Engine noise 2000 Tahoe 5.3

[silvereagle07]

My neighbors Tahoe has been parked for a couple of weeks and he went to start it this morning and it's knocking. Are there any engine issues with the 5.3 from that year? Like spun or seized main bearings? I've seen a TSB for lifter noise but this is beyond that. He said when they parked it there were no abnormal noises.

[clinebarger]

This is the only TSB that comes close to what your describing. If it does have a rod or main bearing problem you shoud be able see fine copper/tin particles in the oil. Drain it into a clean container and see what you got.

Have you heard it yourself? piston slap (commen on 4.8/5.3/6.0 engines)
is a way different noise than a wiped out insert.






File In Section: 06 - Engine/Propulsion System

Bulletin No.: 01-06-01-028A

Date: March, 2003

INFORMATION

Subject:
Engine Knock on Cold Start

Models:
1999-2002 Chevrolet and GMC C/K Pickup and Utility Models
2002 Cadillac Escalade (2WD)
with 4.8L, 5.3L or 6.0L Engine (VINS V, T, Z, U - RPOs LR4, LM7, L59, LQ4)

This bulletin is being revised to add an additional engine to the models section. Please discard Corporate Bulletin Number 01-06-01-028 (Section 06-Engine).

Some of the above vehicles may exhibit an engine knock noise that begins in the first 19,000-24,000 km (12,000-15,000 mi) of use. The knock noise is most often noticed during initial start-up and typically disappears within the first 5-30 seconds (may last longer in extreme cold temperatures). The noise is usually more noticeable on the initial start-up when the temperature is below 10°C (50°F) and may be more pronounced on the first cold start following a long trip.

This noise may be caused by an interaction between carbon that has formed on the piston, the piston motion and the cylinder wall. GM Powertrain Engineering, and an analysis of engines with this condition, has confirmed that the noise is not detrimental to the performance, reliability or durability of the engine.

THIS NOISE DOES NOT HAVE ANY EFFECT ON THE LONGEVITY OF ANY OF THE ENGINE COMPONENTS.

Important: At this time, attempts to repair this condition by replacing the engine assembly or pistons are not recommended.

[silvereagle07]

Thanks clinebarger, that's the same TSB that I read. Unfortunatley, I went to check out the Tahoe tonight. It has a rod knock and what appears to be leaking intake gaskets. Though I didn't see much signs of coolant in the oil. There was a significant amount of condesation build up on the oil cap. I think we are going to swap out an engine.

[heymoe]

Originally Posted by silvereagle07

Thanks clinebarger, that's the same TSB that I read. Unfortunatley, I went to check out the Tahoe tonight. It has a rod knock and what appears to be leaking intake gaskets. Though I didn't see much signs of coolant in the oil. There was a significant amount of condesation build up on the oil cap. I think we are going to swap out an engine.

There is also a recall for the rods. I have a 2002 and it did the same thing. I had two bent rods and the rocker arms were all loose. The dealer replaced all of the rods but the darn thing still knocks at start up when its cold.

[truckdude239]

man thascv really suck hope yal get it sorted out

[clinebarger]

Originally Posted by heymoe

There is also a recall for the rods. I have a 2002 and it did the same thing. I had two bent rods and the rocker arms were all loose. The dealer replaced all of the rods but the darn thing still knocks at start up when its cold.

How does a rod just bend for no reason? The rockers are torqued down on these engines (net lash). I chould not find the TSB for the rods?

Recalls are for safty items.

[bwood]

Is the truck low on coolant?. Condensation can form in an engine that isn't driven much or is used on short trips that never get warm enough to cook off condensation. How is the compression? These engines don't have coolant in the intake so the only way I can think of to get water in the oil is through a head gaskets or cracked head/block. Coolant leaks from the intake went away they started using the Gen III engines.

[heymoe]

Originally Posted by clinebarger

How does a rod just bend for no reason? The rockers are torqued down on these engines (net lash). I chould not find the TSB for the rods?

Recalls are for safty items.

I am not sure but the dealer said it is a common problem. They replaced 2 rods and re-torqued all of the rockers. My tahoe has 75k but I have an extended warranty and they took care of the entire $900 bill.

[clinebarger]

Originally Posted by heymoe

I am not sure but the dealer said it is a common problem. They replaced 2 rods and re-torqued all of the rockers. My tahoe has 75k but I have an extended warranty and they took care of the entire $900 bill.

Im going to say BS. The dealer was sucking up insurance money, and it didnt come out of your pocket so you didnt complain. This kind of crap drives up the cost of buying service agreements.

[heymoe]

Originally Posted by clinebarger

Im going to say BS. The dealer was sucking up insurance money, and it didnt come out of your pocket so you didnt complain. This kind of crap drives up the cost of buying service agreements.

The dealer had to call in an inspector to witness the issue prior to making the repair so I am at a loss to why you think that. I guess that happens allot more than I am aware of.

Anyways hope the problem gets fixed.

[clinebarger]

2 rods get bent at the same time for no reason??? And at the same time 16 rocker arm bolts come loose??? Its hard not to question this.

[STOCKISH]

How long did you guys let the engine run after you heard the noise? I worked at the GM dealer for years and have worked on hundreds of the 4.8, 5.3, 6.0, etc... I have heard these things knock so bad you would think the engine was destroyed and it was just piston slap and would go away once warmed up. Seemed to happen alot worse in cold temps.

[Black 95 TSI]

My 2000 Silverado with the 5.3 does the same thing after sitting for a week, once warmwd up it goes away. I have owned the truck for 5 years and never tore the engine down.

[junkman]

mine too, every morning when it is below 50 degrees or so. Knocks for about 30-45 seconds or so then will quit. Sounds like something is fixing to come apart. Piston slap at its best.

[silvereagle07]

We drained the engine oil and no signs of bearing material. The tahoe got to full operating temp and he drove it around the block. It still has the noise. I'm going to do a carbon clean to it this weekend and see what that does. I know what the piston slap sounds like. I've owned and currently owned GM products with 5.3's or 6.0's. This ain't it. The tahoe does sit for weeks at a time so it could be carbon I guess. I haven't had time to work on it lately.

[silvereagle07]

Well the weather finally cleared up enough around here to work on the tahoe. The more I listened to the engine I knew it wasn't the cold piston slap or a rod bearing. I ran a couple of BG fuel system cleaners through the intake and drove it like I stole it. The engine had severe carbon built up on some of the pistons that was causing the knock. After a few trips around the block it broke loose and flew out. Engine sounds great now and has more power. Thanks for all the info guys.

[truckdude239]

umm going to have to remenber that

[Huck]

I'm on my third 5.3 truck and they all have or had cold start noise piston slap. The 2000 silverado Z71 now has 230,000 miles and still runs super. the Tahoe was sold with 85K--noise but once warm ran excellent. Now my 2002 has startup noise and most of that goes away but NOT all. It just turned 104K miles------BG fuel system cleaner????? Maybe I need that?????? What is BG ??

[silvereagle07]

BG is just a fuel system cleaner we use at the dealership I work at. We use it all the time and it seems to be a great product. We use most of there products everday. You can check them out here. http://www.bgprod.com/products/fuelair.html

[Boog]

My 2000 GMC 5.3 with 151,000 miles has the piston knock on the first start of the day. It's loud enough that I let it idle until it stops before putting it in gear and driving away. Being in a warmer climate I use 10w30 oil in my vehicles. Always change AC filter with oil.
Just curious if a different weight oil has any effect on the noise problem.
And do all GM engines since then have the same issue or what did GM do to stop this? I don't notice my '06 having the same noise at 102,000 miles.

[Daner]

Sorry to dig up this old thread(darnsearchfunction). I also have the morning knockies in my 5.3 01 Chevy. Bought it with 101k now has 129k. Used both 10w-30 and 5w-30. 5w-30 seems to help especially when it's colder outside. Not as loud goes away more quickly. I always let it idle as well.

I think they changed the engines after 02? Not sure on that.

[silvereagle07]

Most of the 5.3 engines have a subtle knock as it warms up. In this case it had a severe carbon problem on the valves and piston tops. Cleaned it with the fuel system cleaner and it's ran like a top since. My 6.0L has a knock until it warms up as well and it's an 07with 75k.