1995 Chevy Beretta Engine Knock, Belt Tensioner

FRED BERETTA

MEMBER
1995 CHEVROLET BERETTA

Engine Mechanical problem
1995 Chevy Beretta 4 cyl Front Wheel Drive Automatic 181K miles

I have a 95 Beretta, 2.2 ltr. Engine, auto. Trans. When it first starts there is a loud knocking noise (I can't tell exactly where it's from, ) then it quiets down until acceleration, then it knocks again. There is nothing visibly wrong with thhe rocker arms or the pushrods. I have pulled the oil pan and there are no metal shavings, nothing that I can see wrong with the rods, pistons, crank, and the oil pump is working. I have replaced the belt tensioner, and the harmonic balancer and assembly. Every thing seems to line up well for the belt, but when I crank it up the belt immediately pulls into the motor right at the belt tensioner, and only the tensioner. And the motor mounts appear to be in good condition. I'm baffled! Do you have any suggestions, please?

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1 Reply

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi:
Does the sound go away after the engine heats up? Is the noise a knock or a rap? Could the sound be coming from a bad wristpin, or does it sound more like a main bearing?

If it sounds like a rod or main, you will need to purchase a product called plastigauge. I believe most parts stores will have it. Follow the directions that come with it. It is used to identify the amount of clearance between the bearing and crank.

If it sounds more like a rap, it could be a wristpin. The pistons will need to be removed to check.

Let me know if this helps or if you have any other questions.

Joe