hi everyone. i got a 2000 blazer. bought it with a blown headgasket with 200k on it. i rebuilt the top end. the gasket blew between the cylinders and no coolant was getting into the oil. when i put it back together i noticed a really light tapping noise from the bottom end. it just now hit 209k and the noise started getting louder mostly when cold. ive always had 20psi at idle and 40 to 60 psi when crusing. i run 5w-30 in it, there is no metal in the oil and never has been when i changed it its always clean not black or anything. i first noticed the noise at around 2500 rpm, and some times when taking off under light throttle ill hear it again but it goes away after like 1500 rpm. do u guys think its a rod bearing going out? the noise is definately comming from the bottom end though. the oil pressure is still stable and never drops below 20 at idle, but has been staying around 60psi since i first heard the noise mostly it used to hung around 45 psi. i have checked it with a mechanical gauge and the readings are close to the dash gauge. i have a crank kit from my previous blazer who decided to spit a rod through the block before i could put the crank in. i just want some second opinions before i pull this motor and change the crank.

 

These L35s can be pretty noisy engines and still be perfectly fine. Well pretty much any 90 degree GM motor for that matter :P I had a 97 with 116K that got the life beat out of it on a near daily basis. I did a full top end build with a beefy cam and it started making a low knock when it got above 17-1800 RPMs at about 85K. It made it through another 30K of pure torture before it let go completely. I would ride it out and pick up a scrap yard motor and freshen that up while the current engine has its final hoorah.

 

the one in the jimmy ticks in the winter time when its super cold. but like said, they are usually pretty noisy engines, especially when they get cold, your oil pressure is good, I would not worry about it too much, but that is my opinion.

 

Its starting to do it more so I've decided to pull it and mic the crank. If its out of spec I'm gonna throw the spare crank in it.

 

If you're going the route of pulling the engine, I would also replace the pistons. I've had more than one truck that had piston slap from elongated journals. I would pick up a master kit and do everything whilst the motor is on a stand. These engines, from my experience, aren't really known to go too much farther than 200-250k. Some obviously do, but if it had a blown head gasket, chances are there is some other damage elswewhere in the engine. Might as well throw an oil pump in there while your at it, as well. Did the crank kit come with a new timing cover and CPS? If not, you also need those and a CPS relearn procedure done with a capable scan tool.

 

If i were you i would also check all the push rods and makes sure all of your rockers are tight, from what I've heard, certain years of the Chevy 4.3 like to bend push rods. I just experienced it. My blazer has 188k on it.

 

Got the motor pulled and oil pan off. Checked all the rod bearings only one had a scratch on it but all the rest still had the really fine machining grooves on the bearings. Crank is in great shape and smooth. I'm gonna mic the crank and plasti gauge the bearings tomorrow. Timming chain was really sloppy. Put the new one on it still has some slack but nothin like the old one. Probably pick up a tensioner tomorrow also. When I did pull it on the lift it was constantly knocking. But very lightly. I'm thinking one of the bearings is right at the point of going south. I will update with the results tomorrow.

 

Blown thanks for the cps reminder. I got a new cover when I bought the chain. I did the relearn when I did the heads. I also used the scanner to set the dist to 0 degrees. It says 0 -/+ 2 but I like to do it by the book so I set it at 0 lol.