Engine "rattle"

LaserRed01GT · Jan 31, 2007

Lost Time said:
Well, to be honest, it almost sounds like two different sounds. The low speed knock at idle, sounds like it's coming from the oil pan. The higher speed rattle is so hard to describe. Inside the car it sounds like a light metal rattle, under the hood it sounds like something more substantial. But it only happens when you float the throttle between 1500 and 3000rpms, and the noise doesn't speed up or slow down in that range. It's just there. Like a heatshield resonating. It just gets louder the closer to the 3k rpm you get, and then any higher in the rpm range and it disappears.

It does not do it under load. It does not do it while accelerating OR decelerating. Only at neutral throttle or very lightly accelerating. The fact that the frequency doesn't change with the rpms makes me believe it's not a reciprocating part, but the description of a rod knock really hits the nail on the head.

Oh, and "clackity" is a better description of the higher rpm sound.

Rod knock will increase as RPM increases. If this noise truly isn't changing along with the change in RPM's, it sounds like something is being resonated outside of the motor.

Can you get a sound clip?

Lost Time · Jan 31, 2007

I'll try to get a soundclip tonight. Best I have is a digital camera that'll take a short movie, hopefully that'll be good enough.

How else might a get a good recording of it?

COramprat · Jan 31, 2007

My crank bolt was loose (I forgot to put the washer back after my cam swap ) and the crank pulley backed off ever so slightly casing the timing chains to rattle. You might just check it to see if maybe, for some reason, you have chain rattle. Maybe a tensioner or chain guide went bad

the98stang · Feb 1, 2007

Like Laser said, pull each injector plug one at a time. If the noise goes away, thats the cylinder causing the problem. It wouldn't be a bad idea to do a compression test. A leak down test would be helpful as well. I highly doubt it's the rods, because your motor would have been gone by now. Check the oil too. Metal deposits would indicate a spun bearing.

MyBloodRunsBlue · Feb 1, 2007

yea as everyone else said, i would get another opinion. if they can diagnose that problem within 2 seconds they may be trying to get ya for your money : )

Lost Time · Feb 1, 2007

FWIW, since the oil change to a heavier 10w40, there is NO noise until the engine warms up. Once it warms up, the higher rpm rattle appears first. Then after the engine has been at operating temp for a while, the idle knock returns.

In light of that, is it possible to have a piston rod bearing problem that ONLY appears when the oil is up to temp? How about piston slap? I thought these were things that generally presented themselves with a cold engine, not one that has been warmed up.

Is there any other problem that tends to show itself once things get up to temp? Lash adjuster, maybe?

I've now driven OVER 4k miles since the car was purchased, and the rattle has not changed since. No loss of driveability, no change in what the oil pressure reads, and no metal in the filter. I did pull 6 of the injectors with no change in the noise. I couldn't reach the two under the intake elbow at the time, but I'll get another crack at them over the weekend.

COramprat · Feb 1, 2007

Unless you have an aftermarket oil pressure gauge the stock one is just an on/off gauge much like an idiot light. It doesn't give an accurate reading.

Lost Time · Feb 1, 2007

http://www.youtube.com/watch?v=ZV1o6sOSQNM

Here's a quick video of the sound. Keep in mind, in only does it once the engine warms up. There is NO noise at all when it's cold.

sicK96GT · Feb 2, 2007

I hear both the sounds, One sounds (to me) like a leak near the exhaust manifold thats more of the clankity sounds. I have this sound right now with my car because my xpipe isnt tight to the manifold... I just need to get under and do something about it.

The other almost sounds just like my engine I pulled out last week, spun bearings.

Just my 2 cents. Goodluck this sort of thing is no fun

steveb24 · Feb 3, 2007

yea when workin on cars there is soo many things to consider. if i know what im doing, i get the job done and be confident with it, and try not to worry. if im not 100% sure i can do it. ill take it to a shop.

stuff i havent done are things like alignment, retaping my head after the plug blew, and gears. Other than that, just be confident untill it breaks, cause like ricky said theres just tooo many things.. check the obvious and call it a day.

DocG · Feb 3, 2007

Ok, I just found this post after I made mine about the 2v Rattle....sounds just like what I keep hearing.

Here's what I know its not....its not a catalytic converter and its nothing with the heads. On the 04 I had, I took off the stock midpipe and cat-back and replaced with a prochamber and cat-back. So no broken cats, no heat shield, and what were the odds that the manifold connections were loose before the install and I left them loose after, cuz it still made the noise.

Plus Ford put on two new cylinder heads, and it still made the noise.

And the 03 I looked at today made the same sound. Wish someone could figure this one out....I'd be a happy man.

If you ever want to read more on this rattle, check my posts from awhile back....I made many a post on this topic.

DocG · Feb 3, 2007

And your's is an auto....mine was a 5spd as was the car I drove today....so its nothing to do with the tranny either.

Will Smith · Feb 3, 2007

this might sound strange. but check your oil dipstick. Check the end for signs of it banging into something. I had a guy come in the other day with the same sound and it was a bent oil dipstick. I am still listening to this clip for you though.

LaserRed01GT · Feb 3, 2007

Lost Time said:
http://www.youtube.com/watch?v=ZV1o6sOSQNM

Here's a quick video of the sound. Keep in mind, in only does it once the engine warms up. There is NO noise at all when it's cold.

Normally when something only makes a noise after warming up, it is a noise that is directly related to oil(bearing clearances), namely those that are dependant upon oil pressure from the oil pump. On these motors, that would pretty much mean a main or big end rod bearing. I hate to say it but that does sound like something in the bottom end.

It's hard to tell from the vid, but it almost sounds like too much crankshaft endplay. Maybe a worn thrust bearing? Misaligned or malfunctioning torque converters can place undue stress on the thrust bearing and let the crank start to walk.

You really should ask around and find someone who has EngineEar electronic scope. They work wonders at pinpointing engine noises.

trinity_gt · Feb 3, 2007

That vid sounds terminal...

I'd drop the pan and inspect the rod bearings.

Lost Time · Feb 6, 2007

I finally got my hands on a stethoscope and after hunting my way around the engine and listening to every bolt I could find, it sounds like it's coming from the furthest rearward cylinder on the passenger side of the motor. When listening thru the valve cover bolt on that cylinder, you can "feel" the sound better than any other place on the motor, although you can hear it from all the other cylinders, just not as well.

It definitely sounds like a sharp metal to metal contact, much more than the rattle it sounded like w/o the stethoscope. Does that shed any light on things?

Lost Time · Feb 6, 2007

Ok, after spending another solid hour listening to anything and everything in the motor, he's what I have found.

The injectors make an incredible racket. More than I could have possibly imagined. What's more, when you listen to them with a stethoscope. you hear what sounds like two pieces of metal being struck together. They are at the same duration and interval as the sound I have at idle. Maybe a coincidence, maybe not. But I can't think of any reason why the injectors would be any noisier once the engine warms up........

On to the more substantial 1500-3000rpm noise. It is definitely coming from the rear passenger side of the engine. If you can imagine the top of the piston hitting a valve every time it comes up to TDC, that's what it sounds like.

Is it possible that once the engine warms up one of the valve springs starts to give-up allowing the piston to hit one of the valves when you "float the motor" in that range? The noise is definitely more audible from the top half of the motor. You can hardly hear it thru the oil pan. Maybe that's a good sign. Or maybe that's what a bad wrist pin sounds like. I don't know, maybe someone else has a good suggestion.

LaserRed01GT · Feb 6, 2007

Now that you think you have it narrowed down to one particular cylinder, try performing a cranking compression test and a leak down test on that cylinder. Also try unplugging that injector and see if the noise changes or goes away.

The piston to valve clearance on these motors is relatively tight. It could be a bad valve spring, lash cap, or something else in the valvetrain.

Do you feel confident enough to pull the passenger valve cover and take a look?

Lost Time · Feb 6, 2007

I don't have the hardware for a leakdown or a compression test. Yeah, I'm comfortable with pulling the valve cover, but I'd like to do all I can externally before I crack open anything.

Short of buying/renting a compression guage, what else I could I do?

LaserRed01GT · Feb 6, 2007

Lost Time said:
I don't have the hardware for a leakdown or a compression test. Yeah, I'm comfortable with pulling the valve cover, but I'd like to do all I can externally before I crack open anything.

Short of buying/renting a compression guage, what else I could I do?

Where are you located? Most auto parts stores will let you "borrow" diagnostic equipment with a 100% returnable deposit.

Have you checked the oil yet for any metal?

Engine "rattle"

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