My 94 Z28 has a loud clacking noise coming from the left side of the engine. It is engine speed related and sounds either like a terrible valve train noise (it's not a lifter click, much louder) or a loud exhaust leak. It goes away if you drive the car a couple of blocks, but if you shut it off for 5 minutes it comes right back when you start the car. Any ideas?? EGR?? Anything else? I still have the stock exhaust manifolds and the car is stock except for the K&N inlet.

Thanks,
Glenn

 

Lifter knock would be my guess. My work truck did it for a couple minutes every time you started it up. After a little while it'd go away. After they changed the lifters everything was fine. Has never done it again. You might need some adjustment.

 

It's pretty loud for a lifter sound. However, I just took a closer look and the rear bolt on the exhaust manifold has broken off at the block. What a pain. I guess I'll have to pull the manifold, try and get the old bolt out and put the manifold back on.

 

I have had similar sounds and your best bet would be to check for any exhaust leak and another thing that really caused bad ticking sounds for me was loose spark plugs. That has happened to me on my 97 Z28 and my 95 TA. So check your plugs and make sure there are no exhaust leaks. Those are most likely the culprit.
JT

 

Sounds like an exhaust manifold gasket leak. I've had two and both sounded mechanical. Check for this first.

 

Thanks for everyone's help. Like I said, I found a broken exhaust manifold bolt. It's the very rear one on the driver's side. So, if I can't get it out, I'll put on headers rather than pull the motor. Do the MAC headers use the very rear bolt hole or the one that's closer to the port?

Thanks,
Glenn

 

talk about reviving an old thread but oh well.
I was wondering the same thing anybody with an answer to this question

 

The MACS do use this hole and I had to pull the head to get the broken bolt out. I went ahead and pulled both heads, did a nice three angle valve job, put on the MACS, and the car really woke up! Went from running 14.3's at 98 to running 13.8 at 103.

 

yea, the problem with me is that my closest drivers bolt (#7 maybe??) is broken probably in the head somewhere and ive been thinking about macs.

id rather just not have to deal with it but i like all the plusses of the macs. how hard would it be to get to that one? or if i wanted to do a hack job i probably could just drill out for the other hole

 

Downside of a hack job is ruining the head. I just wasn't willing to risk it. I couldn't get to either of the back bolts even with a right angle drill. Hardest thing about getting the heads off was getting the steam lines off the back of the heads.

 

yea i was talking about drilling the headers i couldnt imagine that affecting the head?