Carbon buildup on the top of the piston is common. Over time this can lead to symptoms varying from light ticking to knocking noises. Performing a fuel injector cleaning procedure can often help the condition by removing some of the piston top deposits.
Engine Knocking Noise From Carbon Buildup on Dodge Grand Caravan
Average mileage: 129,000 (129,000–129,000)
5 people reported this problem
1998 Dodge Grand Caravan 129,000 mi, Visitor
Knocking/ ticking engine. Very loud almost like a Lawn Mower engine. With a loss of power on acceleration. Have not solved it yet, but will try the engine cleaner.
I blew a rod was quoted 5600 to replace engine etc