nailsfirst

I have a Mercedes E350 2006 146k miles. Just recently there have been a knocking sound coming from the engine. I took it to an Indy shop and they said that it could be the tensioner from the timing chain. But the owner of t.he shop is not present to begin the work because he gives the pricing. The noise starts when I start the car but it goes away while I drive it. He put the stethoscope on the pulley and determined it was coming from.the.engine. He was not able to pull it until the owner of the shop returns. There is also hesitation while driving in low RPMs. I have an oil leak so could it.be low oil pressure. My oil changes are up to date.