Been doing some maintenance on my car and was wondering about some noises I’m hearing. It only occurs when I coast and the engine brakes itself, but it is a sound similar to a boat or jetski at low speed in the water, a ”blub-BLUB" sound coming through my exhaust ( I only notice it due to a break in my exhaust that occurs under my seat, the replacement is on the way for that). It happens at an irregular rhythm.
Is there a probable cause for this?