Engine ticking under load

Discovered a new problem. I now have what sounds like a lifter ticking, but pretty sure it is not a lifter. No noise at idle or coasting(i.e. foot off the pedal). Step on the accelerator and the ticking noise appears. It is relatively loud and can easily hear it with the windows open, but not loud enough to hear with the windows closed. It is loud enough that my son heard it in his car when following me. No noise at idle, however, i did notice it on a cold start with the high rpm, but it went away in a minute or so when the rpms came down. A very light press on the pedal makes the same noise, but at a lower volume.

the cadence or frequency does not change with rpm and why I don’t think it is a lifter. Also, this just came out of the blue. Idler and tensioner bearings were just replaced. A bit baffled on this one. Plan to look for an exhaust leak but haven’t had a minute to get under there. Ignition arcing also popped into my head, but would have expected a cel for misfires. Engine is as smooth as it always has been.

appreciate an ideas or suggestions.

 

Probably going to need some good video/audio tracks to help people help you figure out if/how this is a problem.

The fact that it does not follow rpm is encouraging.

 

Definately made me feel good that it is not likely a serious mechanical issue. On the flipside, am really struggling to figure out what it could be. While I have had many problens that were load related, never had one that gave a mechanical type sound like this. Has anyone ever experienced an exhaust leak that sounded like this?

 

An exhaust leak at the manifold will cause a ticking sound that may get quieter as the exhaust heats up and expands but the frequency should follow engine RPM if that's the case.

 

Thanks. Any other suggestions on where to look for this? It appears to be coming from the drivers side of the engine.

 

Couple other thoughts, if it's only under load it's possible it might be a U-joint, carrier bearing, or other torque-transmitting component. In that case however it would vary with vehicle speed.

If it changes at all according to what gear you are in (whether manual or automatic trans) that would be a possible clue that it's transmission-related.

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Another idea: an unlikely edge case where old/worn engine and/or transmission mounts are allowing the motor or trans to rotate ever so slightly (talking less than 1º of rotation, maybe 0.25 to 0.5º) under load, but just enough to cause something like a catalytic-converter heat shield or any similar piece of flat, resonant metal to make contact with any other part of the vehicle frame or body, resulting in a "tick tick tick" noise.

 

Stab in the dark , have you recently filled up,maybe got some bad gas and getting some detonation. Try running a tank of premium fuel

 

And just for Knowledge. The 4.0Liter engine doesn't have lifters.

 

carrier bearing and u joints were replaced 4K miles ago. the engine rotation idea is great advice and makes sense. Will take a look for that.

Thanks.

 

It has metallic caps between the cam and valve stem, so basically a solid lifter with a set tolerance range for lash. If the lash gets to great, it will tick just like a bad hyd lifter or a solid lifter with too much lash. What am I missing?.

 

Thanks, but pretty confident it is not detonation. I have experience with that and know what it sounds like. Also, it would have to be really bad to detonate at the high idle warm up cycle, where it should be quite rich with minimal advance.

 

If it does not change with RPM that makes it unlikely it's belt/pully related and pretty much eliminates most of the motor's internals. Ticking or repetitive noises of any kind coming from the engine will almost always change frequency with RPMs. Even a loose motor mount. To me that points back to the drive train if in fact the sound doesn't change according to engine rpm and can't be recreated in the driveway.

 

Splitting hairs...There are parts that do the same job as lifters, but they still aren't lifters. The 2.7 L has hydraulic lifters.