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Chevy Cavalier Still Has A Rod Knock?

Q. I e-mailed you about a month ago, Chevy Cavalier Heavy Engine Work, about the 1986 Chevy Cavalier 2.0 liter OHV motor with a bearing knock. I did check out the bearings with what I have learned and found that rod bearing for piston #3 was bad. I could move it side to side on the crank journal. The journal was scored , but it was so slight that you could not hardly feel it with your fingertips.

Chevy Cavalier Still Has A Rod Knock?

I understand that this condition on the crank is enough to need ground down. The rod and cap was in good condition. There is a lot of work involved to taking the pan off to investigate the problem, so I decided to get another motor rather than face the heartaches of practically taking apart the whole bottom end of the motor to replace the crank or get it cut down at the bad journal. Since I replaced the motor and it is used from a junk yard, I have more questions.

Last time I e-mailed you I thought that the transmission was giving me problems also. I had a thought that it may be the throttle valve control cable that goes to the throttle body injected carburetor lever from the top of the transmission. So, after I had this next motor put in and got the car back I immediately changed the TV cable especially since it was frayed and then took it for a drive.

When driving the car I could not make it kick in when tramping on the gas pedal. Plus It seemed and sounded like the motor was revving at a little too high of an RPM when shifting into 2nd and 3rd gears as it did before for the other motor. When shifting into 2nd and 3rd gears it sound like something is slightly knocking and I am hoping that it is not a bearing. The knocking noise is very slight.I do not have an RPM gauge in the car.

I had later realized that I had made a common mistake of putting in a new TV cable which was to hook the clip onto the carburetor lever without pulling out the adjuster first and sliding it back in against the fitting so the throttle lever can pull it out to adjust it. The reason I did this was from being confused because the cable has an adjusting screw that you tighten up after you put it up against the clip that goes onto the carburetor lever.

Then after I had everything hooked up I slid the slider back against the fitting case by pressing the button. Then I pressed the button in again and moved the throttle lever to the fully opened position. This should have adjusted the cable properly this time. I haven't driven the car yet to see how it shifts due to the sun going down , so I will test it tomorrow.

About the knocking noise, I tested the motor by putting it into gear with the brakes on and revving the motor and I didn't hear any knocking noises and no tapping noises at all. It also sounded good at the junkyard while still in the other car. When the mechanic put the motor into the car he said it had a slight knock that went away when he adjusted the timing, I believe he said he advanced the timing.

Now that you understand the problems, what should I do? Is that slight knocking noise, during shifting when sounding like the RPM's are a little high, a bearing knocking or is it in the transmission? Why would it have a slight knock before the timing was adjusted and would it be a bearing that the mechanic was hearing since it went away with the timing adjustment?

If it is not a bearing knock then what else could it be since it didn't knock when being revved while in gear with the brakes on, but does make some kind of knocking noise when shifting? Would the misadjusted TV cable or the other faulty and frayed TV cable cause the transmission to rev a little higher than normal when shifting? Does the TV cable actually control the shifting or is it just for passing gear?

This should do it for my questions. Sorry that it is a little lengthy.

Thank you,
Ed

A. I have just one question, why are you putting so much money in a 17 year old car? I would need to hear this "knock" to be able to tell you my opinion. All these engines had piston slap problems. It could also be a carbon knock which would clear out after driven. Just drive this thing for a while and see what develops.

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