Okay, I'll let him know. It was a truck that was recently purchased. From what I can understand the overhaul was done within the last 200K Miles....
He said the tach fluctuates, and he believes the engine does as well, he said he can hear the engine as well.
My dad has a 1999 Freightliner XL Classic with a 3406E Cat engine in it. When he uses the Jake Brake, he has an issue with the RPM's fluctuating....
