Say hello to my new friend! His name is rod knock.

nocones said:

What's the pulley ratio on for accessory drives?  I counted about 35-40 hits during your 11 second video.  If we assume 40 during 10 seconds that's 240/min.  Rod Nock would likely be 1-2* per rev (I'd think) as the piston changes direction.  If I'm off by my count you could be in the 1/4 of RPM range that would be valve train.  Are they interference engines?  What's idle speed?  It could be 1/2 idle speed and is just a cracked exhaust manifold.  Is the AC on in your video?  AC compressor or clufch failure could sound really loud and would be at some strange multiple of engine speed.

Sucks not matter what it is though.  You don't expect a low mile car to need this kind of attention.

Posts like this are exactly why I asked you guys!  The a/c was on. It's in Florida so it's always on. I'm not 100% sure where the compressor is but I'll try it with the a/c off. Next step is figuring out how to remove my serpentine belt so I can try it without that, although it does kinda sound like it's from the drivers side top of the engine.  so it very well could be a lifter or something of that nature. 

Another thing to test if the first round of stuff doesn't narrow down the noise.  Start the car, then give it a small rev.  If it's a rod bearing, usually the sound will change when you let off the throttle and the engine goes from accelerating to decelerating. 

In reply to rslifkin :

Last time I gave it a small rev (yesterday) it sounded like a bunch of gravel or steel balls rattling around in the engine.  It was a very nasty sound.  

Turned it on briefly and made sure the A/C was off.  No change in sound.  Right now I'm working on removing the serpentine belt to see if that changes anything, although I'm not expecting it.  I believe it's coming from that driver's side cylinder head.  I don't have a stethoscope but I do have a big screwdriver so I'll try listening around with that next.

Removed the serpentine belt, turned it on for a second and no change in sound.  So now we're going to put the belt back on and remove the valve cover and look for pieces of broken metal, basically.  We'll try to jack the car up and drain the oil and look for metal in there as well.

z31maniac said:

TGMF said:

Thought the 5.0's were supposed to be solid engines?  

They are. But the reality is, sometimes E36 M3 fails.

You know how every job has a guy that fills in for people on vacation. He knows how to do every job almost as well as the guy he's replacing. He built this engine.

Valve cover is finally off, what a pain in the rear.  We did not find any metal, and all the valve springs felt nice and tight.  The cam lobes all looked in great shape to the naked eye, at least.  Turned it over a few times, and the knocking definitely sounds like it's coming from the front area of the engine.  I'm trying to avoid turning it over any since I know that's doing more damage, but I'm just trying to figure out what's going on so I can fix it.  Tomorrow I think we're going to turn the engine over a few times with the valve cover off and take a short video and compare the speed of the tapping with the speed of the cams spinning and see if they line up.  If the sounds don't line up then we'll jack the car up, drop the oil pan, and look for damage on the bottom end.  Also I just looked it up and the coyote is an interference engine.

I've been searching around for anything I can find on mustang forums and mostly I just find all the standard ticking that comes from the valvetrain.  However, I did find this video on youtube, a "spun/knocking rod bearing noise."  That sounds about exactly like what I've got.  I don't have low oil though, in fact I keep my oil levels on the high side after reading that people that race the Coyote V8 often do that (even though I don't race mine).  He needed a new long block, hopefully I don't.

https://www.youtube.com/watch?v=e79c_-_hVa8

Any further developments? Something I just thought of (which might be a waste of money) is to send an oil sample off for analysis.

At this point I would drain the oil and cut open the filter. You'll know pretty quick if it spun a bearing. If you don't see anything then it might be worth pulling the oil pan to have a look at the bottom end. To be honest, it doesn't quite sound like rod knock to me but diagnosing anything from a video is tough. 

Bumping this up to the top

That sounds just like der Scheißewagen sounded when the rod bearing disintegrated to the point where the piston was striking the exhaust valves.  My noise was happening at exactly 1/2 engine speed so I was pretty convinced it was a valvetrain problem, but no such luck.  Drop pan, cut open filter, look for metal.

I'm putting my money on timing chain guides. The only thing I've ever heard similar noises from is Audi 4.2L with bad timing chain guides. 

Failed timing belt tensioner in my KLDE probe GT sounded like a rod trying to exit the block. I'd be looking at everything external, listening with a garden hose stethoscope, etc, before committing to rip into the internals.

You can buy a (24? 48? 72?) Hour pass to ford's full service manual online. The thing is, you can print out the parts you need (or pdf them) while you have access. I know money is tight, but it might be worth doing to get the whole timing chain service, and rod bearing replacement procedures before digging in further if you're worried about your experience level with such jobs. Be better to diagnose first if possible of course.

I had a harmonic balancer that was bad make a sound like that in a Nissan engine. 

In reply to Brett_Murphy (Ex-Patrón) :

A loose crank pully bolt can sound like a bad rod bearing on a 1.6L Miata.  Sometimes you can see them slapping back and forth.  

Sadly, this sounded like a bearing to me.

This sounds almost too tinny (high pitch) for a rod.

In reply to Paul_VR6 (Forum Supporter) :

I agree. That sounds external to me, not inside the block.

In reply to rslifkin :

Exactly.   Sound also is a little deeper

I'd pull the trans and have a look. That's much easier to do on the ground than an engine swap. Any chance the noise changes with the clutch pushed in? 

Have you drained the oil and checked the pan and filter for metal debris yet?

It's 20 minutes and maybe $50 if you refill with synthetic that you can spend to eliminate the bearings and such with about 95% confidence.

In reply to Brett_Murphy (Ex-Patrón) :

My driveway is sand so I can't jack the car up on it.  Tomorrow I'm going to pick up some ramps to drive the car up on so I can check for any evidence of metal debris.

I still feel it's the timing chain tensioners but it'll feel good to rule some serious things out!

I'm guessing knowing it is or isn't the bearings will be a relief, either way.

Well it's definitely bearings of some sort.  I removed the filter today and cut it open with tin snips, and there was a metallic sheen in the oil and pieces of bearing in the filter element.  So I'm guessing one of the rod bearings perhaps is toast (which explains the knocking noise) but there's still the issue of the metallic squeak/tapping that's up at the front top of the engine.  I guess it's also possible that the noise is simply really loud rod knock that's echoing through the entire motor, making it sound like it's from somewhere else.

If it's something like a timing chain guide failure and there are any plastic coated metal pieces, that could explain metal bits in the filter.