QuestionQUESTION: I have a 2002 Disc with 105000 miles. A loud ticking noise has started coming out of the top of the motor, both sides of the intake manifold. Sounds like lifters whacking. Any idea of what it might be. Maybe the oil pressure switch? No oil pressure warning light? thanks.
ANSWER: A loud rap can come from several things:
1 - If the engine loses oil pressure the valve train will rap loudly
2 - Lifter failure or rocker shaft failure will also cause loud valves
3 - A broken catalyst can sound just like a rapping engine
4 - The secondary air valves can rap on top of the valve covers
5 - Excessive piston skirt clearance will cause a rap when hot
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QUESTION: I have isolated the clacking noise to be coming from the passenger side of the engine furthest back under valve cover. It only rattles after the engine is good and warmed up, and stops with the slightest of throttle. I can only think it's a bad lifter? What do you think?
Thank you for all your help. TC
AnswerIf the noise is coming from inside, it could be a failed rocker arm, a bad lifter, or it could be piston noise. In the rear of the engine, it could also be noise from the cam moving. At this point, all you can do is dismantle the top end and see if you find a fault. If not, you would have to pull and tear down the engine; probably change pistons/liners etc. Some would do that; others would just drive it and see what happened.
The problem is, many times, you don't see a lifter or rocker problem, so you know the issue is deeper inside. So you have to decide if you want to engage in a costly re-linering and total overhaul. Since a failing rocker or lifter will not lead to wider failure, many owners would elect to leave it together and see what happens. If the engine does something worse in the future, you are still in the same place - overhaul
