engine knock

[nodram]

I am having motor knock with my '92 mtx with 128,000. I was reading through past threads and saw the exact same descrption of engine knock that I am having. A typewriter like ticking on the topside of the motor towards the back by the firewall. The knocking speeds up as the idle increases. I had the valvecovers resealed and the EGR changed. Some people posted that it could be bad bearings or timing belt. Here is the thing that the other post didn't have. There is a valve or lever on top rear of the air plenum by the firewall that when it is moved the ticking will go away. It's like it lets more air through because now the ticking goes away but the motor now has too much air or vacuum (i'm guessing here) and it will idle rough untill the rpm's are brought up and the ticking will come back and the car will idle normally. I have heard of the air plenum or manifold getting carbon deposits in ports that need to be cleaned. I have never done that, any help would be great, thanks.

 

[SHO#7]

I think that you are talking about the vaccum canister that activates the secondaries. IIRC vaccum holds them closed and vaccum is removed for them to open. Maybe the car stumbles with them stuck open, making the noise hard to hear because of the erratic idle... You can drain your engine oil and look for rod bearing bits. Or pull the top timing cover off and check out the belt to see if the tensione STB. Has the timing belt ever been replaced?

The two rod bearing failures that I saw did not make noise until around 2200 or so rpm. But it sound like bearings to me. Drain the oil and check it out for RB bits. Or get a stethascope and listen around the motor.

Good luck
Mike

 

[TYSHO]

There is a valve or lever on top rear of the air plenum by the firewall that when it is moved the ticking will go away.

This has been a problem for a few members.

 

[oxrox]

I have the same tick...tick..tick - it is really quick (like 2-3 per second) and sounds like a sewing machine at idle....it is at the back by the firewall.

It appeared after to upper 60k - I am hoping to go in and recheck my valve shims.

Ryan
95 ATX