TwoBobsKJ
Full Access Member
So this has been tackled before in some fashion but I haven't seen a thread on this particular sound in the 3.7L engine. I'm just shy of 123,000 miles.
There are times when I hear a distinct 'rattle' or higher pitched 'knock' that is perfectly timed with engine speed - but especially when quickly pressing the throttle - that is loud enough to hear from inside the Jeep. It's not a 'knock' like a rod would make down toward the crank and it seems to come from the top front of the engine - doesn't seem to be coming from the valve train on either side. When I pop the hood and blip the throttle I can distinctly hear it on the top of the engine - like I said more of a rattle sound than knock but it's internal.
Doesn't matter if the engine is hot or cold - though it happens more frequently when the engine is hot versus when it's cold. And it only happens when it's under load - a quick blip of the throttle or when accelerating, not at idle. And it's not there all the time; it'll be there for a few minutes then disappear and will randomly appear again a few minutes or a few days later. But it is happening more frequently recently.
Could it be related to the timing chains? Is the chain starved for oil due to blockage? Should I be ready for the engine to grenade on me? (I doubt it but what the heck, right?) Is it piston slap (don't know exactly what that means...)?
Like I said, I've seen lots of threads about the 3.7 'ticking' but not this type of sound from the topside.
Thoughts?
Bob
There are times when I hear a distinct 'rattle' or higher pitched 'knock' that is perfectly timed with engine speed - but especially when quickly pressing the throttle - that is loud enough to hear from inside the Jeep. It's not a 'knock' like a rod would make down toward the crank and it seems to come from the top front of the engine - doesn't seem to be coming from the valve train on either side. When I pop the hood and blip the throttle I can distinctly hear it on the top of the engine - like I said more of a rattle sound than knock but it's internal.
Doesn't matter if the engine is hot or cold - though it happens more frequently when the engine is hot versus when it's cold. And it only happens when it's under load - a quick blip of the throttle or when accelerating, not at idle. And it's not there all the time; it'll be there for a few minutes then disappear and will randomly appear again a few minutes or a few days later. But it is happening more frequently recently.
Could it be related to the timing chains? Is the chain starved for oil due to blockage? Should I be ready for the engine to grenade on me? (I doubt it but what the heck, right?) Is it piston slap (don't know exactly what that means...)?
Like I said, I've seen lots of threads about the 3.7 'ticking' but not this type of sound from the topside.
Thoughts?
Bob