Can any one tell me what a bad wrist pin sounds like?Is it hard and loud like a bad rod bearing, or is it more like a bad lifter tap? The sound I am hearing is coming from the center of the right bank just behind the motor mount. It is a tapping that can be heard good with a stethoscope the engine is a 2000 chevy 4.3.


Thanks

 

What you are describing sounds more like piston slap to me. A wrist pin noise would be similar to a lifter tap, but louder.

 

At what RPM are you hearing it knock? I still have two knocks in my 97 4.3 one that comes in at about 2000 RPM with NO LOAD, UNDER LOAD I don't hear it. It has been doing it for 12,000 miles hasn't gotten worse. I was going to replace the engine but as long as it keeps running I will just drive it. It runs great except for the knocks. I also have a knocking noise at idle that who knows what it is, It doesn't seem to be connected to the other knock I only hear it at idle. It has not changed in 12,000 miles. So I have just decided it can knock all it wants as long as it keeps running. I had a 1973 IH 4x4 pickup with a 345 cubic inch V8 & it had a knock, so I completely rebuilt the engine All new bearings, crank, cam, etc, had the heads rebuilt completely, put it back together & 50 miles & the same knock was back. I drove it for 70,000 more miles sold it to a friend that drove it for at least 5 more years before he got rid of it & it could still be running. When the Blazer blows up I'll call a tow truck & have it towed off the road & decide what I'm going to do. This knock has been heard by 4 different mechanics & every one has said it was something different, all said it would go much longer & I would find out when it blew up that was like I said 12,000 miles ago & it is still running great & knocking. Being a retired mechanic myself it must not be anything too serious or it would of come apart by now.

 

At idle I hear it sounde like a lifter or rocker arm. Worse when cold but some times I do not hear it. Then it comes back when I am driving it get faster and sounds like a spark knock.

Can not find the source.

 

Yea mine does the idle knock. But like I said I can't figure out what mine are & neither can 4 other mechanics. It could be a piston slap, but a wrist pin is more likely. Have you changed the oil if so what are you running weight wise. I run Valvoline Synthetic 10-30. I drove a piston slap on a 302 Thunderbird for thousands of miles & it is still run today. But a piston slap as a rule quits when it warms up. I would just drive it until it gets worse. The 4.3 are as a rule good engines but in the Blazers they seem to not live as long. All these newer engines are known for noise. They are building them with lighter materials. When mine goes I'm going to rebuild it, buying a used one or even a reman isn't well spent money IMHO. $3000 out the door is about the going price. Heck you can't buy much for $3000.

 

I am running 5w30 with an AC delco oil filter. The engine has only 68000 miles no it. It is in a 2000 Blazer, it has been well taken care of. It runs great with the AC or radio on I can't even hear the tap. But I drive it back and forth from Kentucky to Florida quite often. I am just thinking that it will break on one of the trips.

 

I say just drive it. Carry tow insurance. I carry mine through my insurance company because I can call any tow service & have it towed where I want it towed. The down side is I have to pay up front & it takes a week or so to get a check from the insurance company. I would rather have it that way than sit on the side of the road for hours waiting for AAA. I have Farmers Insurance & they have been real good, the one time I needed a tow.