Hello all,

First post on here. Just to start I’m not a gear-head by any means, so bear with me if my terminology isn’t always top notch. This noise has been driving me crazy, so I’ll do my best to explain

Cliffs
Loud rattlesnake/card in bike spoke sound while warm & accelerating, noise gets faster or slower with rpm's. Doesn't matter if parked or driving.
Doesn't make noise while idling (Update as of 7/21/16 - noise has appeared off & on while idling after I made a 70 mile trip)
Doesn't go away when in 4WD
Possible lifter or exhaust manifold issue?

Background
I have a 4WD 97 F150 4.6 with approx. 270K miles (a lot I know!). Semi regular maintenance and oil changes. I used Castrol extended mileage 10-40W for the longest time, but went for a period of 6-8 mos using Castrol 20-50W (probably not the most beneficial, and noise issue happened while I was still using this oil.) Around 2 months ago I switched to Castrol extended mileage 5-30W. The most recent work done to the front end was a tune up around 12 mos ago, and I had the head’s replaced approx 4 years ago. Also had my tranny rebuilt recently, which had no effect on the noise.

Problem
I have a noise coming from what sounds like the top driver side or middle area when I accelerate, but I can’t confirm the location. The best way to describe would be a rattlesnake’s rattle, or a playing card in the spoke of a bicycle. It doesn’t occur every time I’m driving, but the vast majority (>75%), and the noise seems to speed up or slow down depending on how fast I’m accelerating (usually anywhere between 1,000 – 2,500ish rpm’s). I can also hear it after I’m done accelerating and take my foot off the gas, but the clicking is much slower (almost sounds like its winding down) and gradually ceases. I can hear the noise while I’m revving in park, or if I’m in drive with the brake depressed and accelerating, but there is no noise while idling - (update as of 7/21 - occasional noise has appeared while idling, almost a knocking sound), and the issue never arises after a cold start, only after the vehicle gets up to its normal temperature (usually takes anywhere from 5-10 mins). The noise also doesn’t go away if I put the truck into 4WD, which seems to rule out a possible IWE issue.

Possible issues?
I’ve been to a couple of independent mechanics, with my most trusted thinking that it’s a worn lifter (think the correct term is valve lash adjuster for these trucks). He did a test drive and some inspection under the hood, but didn’t take out anything. I’ve also heard the exhaust manifold could be an issue just based on noise observation. I initially investigated the noise because I thought it was a timing chain issue, but neither of my mechanics believe so, and it doesn’t really sound like it imo (no slapping, doesn’t make a sound on start up or idle). I’ve also watched videos related to the cam phasers.

1st link is of me accelerating from a stop. You can hear the noise audibly until around 20 seconds. Notice that it briefly goes quiet anytime the vehicle downshifts (yeah I need some new tires too haha).
2nd videos is in park while compressing the accelerator. Noise is audible throughout.

 

Sounds like an exhaust leak somewhere, probably a cracked manifold.

 

Has anyone used a mechanics stethoscope to locate the noise area?
And why are you using all that heavy oil?
The oil is speced as 5W20 or 5W30. Preferable is 5w20.
This motor does not need that heavy oil.
One reason is the cam chain tensioners are oil pressure operated. Your wearing them out with the heavy oil, especially on cold starts when the oil viscosity stays high longer .
Good luck.

 

The first thing I would check is to make sure my spark plugs were tight. One could be aout to blow out.

 

Thanks everyone for the responses.

I don't believe anyone has used a stethoscope yet but not 100% on that. No reason on the 20-50 except bad advice, seems like the noise appeared around the tail end of my usage with that grade (May 2016) coupled with the knocking sound that's now re-appeared off and on while idling. I had an oil change with Ford shortly after the noise appeared (using 5-30), and although the noise was still prevalent the day I got the truck back, it went away less than 2 days later......then re-appeared several weeks later (I had a 70 mile trip a couple days before, sat the truck for a day or 2, then the noise came back).

I had a tune-up last year and some spark plugs replaced (not sure if all of them) but I've noticed recently that I'm definitely having some issues accelerating at lower rpms (lots of bumping and hesitation). Seems like this developed and got worse last Friday when the idle noise returned.

I'm thinking about just going to the dealer and paying them to inspect, but was advised to get another oil change using 10-40 full synthetic first, and see if that clears anything up. Any thoughts on that? I find it strange that the noise went away for a while after my last oil change, but am thinking that switching to a slightly thicker synthetic may be better for the heat (i'm in georgia, it's primarily 90's right now) and using the synthetic may help clear out any burned on gook with the lifter tube (if that's the actual issue).

 

Plugs torque is great place to start

 

Do NOT use 10W40 - use 5W20 or 5W30 ONLY.

 

Valve train noises are half the RPM of the engine, so keep that in mind if you're trying to narrow down your search area

 

I opted not to do the oil change and just let my other mechanic try to diagnose. He called me this afternoon and said I had considerable misfiring (which I noticed last week around the same time that the occasional idle knocking appeared). He thinks the misfiring is due to worn coil packs or a loose spark plug, but he's still looking into the rattlesnake sound.

I listed off everyone's suggestions in the thread, so hopefully this will help narrow down the search.

 

Please close this thread. After much time and many attempts to diagnose the truck to figure out exactly what is wrong with it, I ended up trading it in towards another car.