I have a 78 300 SD with 121 K miles. I hear a constant tapping coming from the engine. The tapping is not as noticeable at idle, but increases and becomes lounder as the RPM's increase...I just purchased the car a few weeks ago, the previous owner had it sitting in a garage for about 8 years...I had the oil changed hoping this would help cure the tapping...no luck...Could a valve adjustment eliminate the noise? Or do you think its a collapsed lifter? Any thoughts on the cost of repairs?
P.S. I find this forum to be an incredible wealth of information...Thank you, Juan G.