start up engine clunk

[muff34]

Hi Everyone
Just purchased a 2000 Silverado with a 4.3 v-6 144,000 miles on it and kind of curious about something. When the engine is warm sometimes when starting I can hear a clunk coming from the motor. probably piston clunk but just looking for ideas or somewhere else to look. Also when running down the road this thing turns a low RPM and when you add fuel a noise comes from somewhere that would make me think of pinging sound from old engine that maybe has pre ignition knock al tho this is not quite the same ping, it not a real loud noise but something i noticed. Any comments welcome just looking for direction
Thanks Muff

[troy1]

Piston slap reminds me of more like a rattle a clunk makes me want to say main bearings.

[muff34]

Originally Posted by troy1

Piston slap reminds me of more like a rattle a clunk makes me want to say main bearings.

oh oh, ok then is there a way that I can tell if the main bearings are going with out having to go internal

[corning_d3]

Originally Posted by muff34

Hi Everyone
Just purchased a 2000 Silverado with a 4.3 v-6 144,000 miles on it and kind of curious about something. When the engine is warm sometimes when starting I can hear a clunk coming from the motor. probably piston clunk but just looking for ideas or somewhere else to look. Also when running down the road this thing turns a low RPM and when you add fuel a noise comes from somewhere that would make me think of pinging sound from old engine that maybe has pre ignition knock al tho this is not quite the same ping, it not a real loud noise but something i noticed. Any comments welcome just looking for direction
Thanks Muff

You do know lugging is a horrible thing to do to any engine... I've heard of wristpins making this noise, but it's more than likely in the bottom end..

[muff34]

Originally Posted by corning_d3

You do know lugging is a horrible thing to do to any engine... I've heard of wristpins making this noise, but it's more than likely in the bottom end..

I hear ya about the lugging but it`s an automatic and so would assume that they all run the same. My other vehicles turn 2000 -2100 at highway speeds this is only turning about 1500 at 60 MPH. Well just have to wait and see I guess.

[wrparks]

1500 RPM at 60 mph on the v6 is a bit low I think. Mine runs at about 1600 to 1700. At 55, it runs 1500, but it goes up real fast once you get past 55mph. Plus, doesn't piston slap only appear on cold engines?

[muff34]

Originally Posted by wrparks

1500 RPM at 60 mph on the v6 is a bit low I think. Mine runs at about 1600 to 1700. At 55, it runs 1500, but it goes up real fast once you get past 55mph. Plus, doesn't piston slap only appear on cold engines?

Well maybe my tach is out abit I don`t know. I`ll have to let the local GM tech have a listen I guess , hopefully nothing to worry about ,just nervous with high mileage. BTW If yours is a v-6 what kind of mileage are you getting
Thanks Muff

[wrparks]

From what I've read and heard, the v6 and v8 mileage is about the same. Mine is the v6 w/ a long bed and a mammoth 32 gallon tank, so it has some added weight compared to some, but I average about 18 mpg w/ mixed city/hwy driving. Have gotten as high as 23 i think w/ cruise set at 55 on highway for a long trip. The worst was 16, and that was just an awful week of stop and go bumper to bumper traffic.

[mcangas]

i believe that my piston slap in my 03 siverado was solved by replacing the cats. It took alot of patience to pin point the noise,but now its gone .cat warrinties are 80000 miles

[kinetica7]

Originally Posted by muff34

Hi Everyone
Just purchased a 2000 Silverado with a 4.3 v-6 144,000 miles on it and kind of curious about something. When the engine is warm sometimes when starting I can hear a clunk coming from the motor. probably piston clunk but just looking for ideas or somewhere else to look. Also when running down the road this thing turns a low RPM and when you add fuel a noise comes from somewhere that would make me think of pinging sound from old engine that maybe has pre ignition knock al tho this is not quite the same ping, it not a real loud noise but something i noticed. Any comments welcome just looking for direction
Thanks Muff

I have a 99 Dakota v-6. I got the CLUNK too. My clunk is constant with the engine in drive or reverse sitting at idle. The prybar-stethescope told me it was coming from the front of the motor. I have replaced all the main/rod bearings and oil pump. It made the clunk quieter but it still does it. Most likely a piston, rod, or wrist pin doing something its not supposed to do. At this point I have already dumped $300+ in the motor just in bearings and seals and I am becoming hesitant about tearing it down and throwing more money into it. O by the way when the clunk started it was quiet and it got loud in a matter of weeks. I did notice about 1/2mm of play in my pistons but none in the wrist pins. Anybody have any more ideas?

[Silverado_guy21]

I have a 01 Silverado and i was wondering about the start up noise its got a 5.3 and it only does it when i start it cold gets warmed up everything is fine. I also have a couple friends that have newer chevys and theirs does the same thing can anybody give me some good advice?

[corning_d3]

I was in an '04 today and got the same noise when the engine was cold, but only under a load. I didn't spend much time with it, but knowing GM and their undersize/low friction pistons, I'd say piston slap is a pretty common thing. A lot of the 3X00 V-6's had this same issue..