My 85 300D KaliKar (California model) is making a LOT of rattling sounds when I drive at partial throttle.

What I mean by partial throttle is the situation of driving at a constant 30 MPH. You are not mashing the accelerator pedal to increase speed, just holding it constant. I hear these sounds when holding any steady speed from about 15 up to 40 MPH. The sounds are even more pronounced when I am holding the throttle slightly open and rolling down a slight incline.

I have also noticed that the sounds are lessened when the engine is fully warmed-up.

Please note that this is a KaliKar, so the usual air cleaner bracket issues don't exist on my car. And I changed the motor mounts about 8 months ago and they appear fine.

The slight incline point I made above worries me; could this be a slack timing chain possibility--tensioner at full extension but not quite enough to take all slack out, engine being rotated by going downhill but not because of the throttle. I have no indication of any timing chain/tensioner maintenance by previous owners.

Any advice appreciated.

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Mike Frederick
1986 300SDL, 240K+ miles
1985 300D KaliKar, 270K+ miles