Knock Down Below

My 92GT has had a knock for couple of weeks, and I attacked the problem this weekend as if it was a rocker arm hitting the valve covers.

I did this partly because I've been wanting tall FR covers and a 1" spacer fro a while, so I put them on and also removed all the smog equipment and plugged the holes. When I removed the upper intake and valve covers to inspect the rocker arms and rods, I did not find any that were loose our unusual.

I have GT-40Y heads with steel Comp Cam roller on stud mounts, and I did not find any of them rocker arms loose or anything unusual under the valve covers.

After I put things back together, I noticed things a bit quieter with the smog equipment gone, but the knock was still there.

The knock is more noticeable when I am below the car, and the sound draws me to the crank or the water pump/timing chain area of the motor.

Any advice with this? With over 200k on the motor, my thought is that its going to need to be pulled and worked over.

Sigh of Relief?

I took advice from another post, and I think I have a sigh of relief in that I do not hear a knock when I run the engine without the serpentine belt.

This tells me I have a accessory or water pump knock, which is a lot easier to handle than a lifter or bearing inside the motor.

What's the most likely cause of an accessory knock that sounds somewhat like a rocker arm hitting a valve cover?