I recently had the clutch in my '03 Mazda B2300 (with about 157,000 miles on it) replaced. After the work was done, the clutch is working great, and the truck runs fine, but I noticed an annoying clatter that seems to be originating from the front, driver-side of the engine. The noise is directly related to engine RPM—the rattling noise speeds up and slows down with the RPM. I'm puzzled as to how work on the clutch could result in a change in the engine noise and I'm hoping someone here might have an idea what's going on. I plan to speak to the foreman in the shop that did the work, but I would welcome any insights about this odd issue. It sounds a bit like what one might hear with an old school engine adjusted with excessive valve tappet clearance. I believe the 2.3 liter four has hydraulic lifters?

A second issue that cropped up post-clutch rebuild is that the heater valve does not seem to be closing. This issue may be totally unrelated to the clutch change, though it's possible that the vacuum line to the valve was inadvertently disconnected or cut during the clutch work process. I didn't notice the issue till a few weeks after the clutch work. I've changed the heater valve, but the issue persists—if the vents are open, the heater seems to be operating as though the coolant is cycling through the heater core regardless of where I position the dashboard temperature control. I suspect that the vacuum line which controls the valve has been disconnected somehow. I assume the tubing entering the valve's body is a vacuum line? I'm planning to disconnect the vacuum line with the engine running tomorrow to see if I can feel any change in suction with the temp control valve in the cold and warm selection positions, and if not, trace the line to its source to see if it's been damaged.

Thanks in advance for any guidance.

 

I found this YouTube video on replacing the heater actuator which might be the problem with my heater. Not sure how to troubleshoot the actuator exactly.

You Tube

 

This is also informative if the blend door actuator and temperature control are the issue. The post has information on accessing the components in question and testing the temp control potentiometer with a volt-ohm-meter: