Engine Knock

[Underdog]

Hopefully someone can shed some light on this.
I have about 120,000 Kilometers on my Pilot. At about 90,000 it began making this noise. I took it to a Honda Dealership. Their response this noise is "Normal".

I took it to a local mechanic, one I can trust. He did a valve adjustment. No Difference. He did disagree that this "Knock" is "Normal" for a Honda he felt it was nothing to worry about.

It seems to be worse in colder weather.

Gas mileage is fine, it still runs like a dream, and the oil has been changed every 5000 Kilometers. I have owned the vehicle since new.

Here are videos on the noise.

Cold Start Up on Vimeo


Warm Idle on Vimeo


Any thoughts?

Thank You

[rocky]

What grade oil are you using?

[Underdog]

Originally Posted by rocky

What grade oil are you using?

The shop I go to uses Castrol and the grade is what Honda Recommends.
I believe 5w 30.

I do not use Synthetic.

They have tried adding Lucas Oil treatment once, no difference.

[humanoid]

Honda recommends 5w-20, not 5w-30. I wouldn't be using that grade in colder weather either.

[Underdog]

Originally Posted by humanoid

Honda recommends 5w-20, not 5w-30. I wouldn't be using that grade in colder weather either.

Then that's the grade they are using. They use what Honda recommends.

[rocky]

The first number is the key for cold starts. The second number ensures protection at high temperatures.

Motor Oil Viscosity Grades Explained in Layman's Terms

Having had a local shop drop the wrong viscosity oil in once (I could tell) I'm suspicious as to what they actually put in there the last time.

But then again, up in Canada, they should know its real important to get the right stuff in there especially in winter.

One small caveat in my off roader I do drop to 0-30 in winter simply cos it makes a difference in the way the engine gets oil pressure up in winter.

[ptsmh73]

Your video/audio clips are very helpful and clear. Does the noise get worse when the engine is in gear (driving), stay the same, or get quieter? How long has it been doing it? Has it gotten louder over time or did it start all of a sudden? Can you hear it with the hood closed? Have you tried a higher octane gasoline?

The noise is definitely not normal, but I can't tell you what it is. To me, it sounds like something going on inside, maybe a worn bearing on a single piston or at the cranksaft that "clicks" with each revolution of the engine becuase it has play in it.

There has to be someone familar with engine noises that can tell you exactly what the noise is. Hopefully, it is annoying but "harmless." Good luck.

[rooster59]

I would take belts off one at a time and see if it goes away. It sounds like my civic did, bad a/c clutch bearing. Not saying thats what it is, but it's an easy test. Make sure you have a way to reset codes if you trip one cause a belt is off.

[mclairmo]

I often use my automotive stethoscope to try to pinpoint engine noises. Place one end on an engine part, like the a/c compressor, and the other end in your ear and see if you can pinpoint. Might be able to isolate it to an easy and cheap to replace part.

[dustino8]

I've got the same noise under the hood, though not as prevalent as yours. To me, it sounds like its coming from the driver's side towards the firewall, near the valvetrain area. When I open the throttle (increase revs)from under the hood, the noise disappears. Once the revs are back to idle, the noise takes 20-30 seconds to return.

I'm not concerned at this point, as I've had worse sounding noises coming from under the engine bay on other vehicles.

Keep us posted if you find the culprit.

[Underdog]

Thanks for the replies.

It is not an oil issue. The mechanic that did the valve adjustment for me commented how clean the top end was adding " You obviously change your oil religiously".

His theory is that it is possibly "Piston Slap". He added Honda's are not known for this (not like GM) but he suspects that is what it may be. He tested the engine at various RPM's and temps. The noise lessens as the engine heats up.

The knock is not nearly as noticeable in summer as in winter.

He felt it was nothing to worry about, just annoying.

And it does just annoy the "Bleep" out of me .................

I like the suggestion of removing belts.............I will try that..........

The noise has been consistent since it started..........no change........

Once the weather gets better I will investigate more. If I find the culprit I will advise.

[tterag]

I have 122K on my 2004 Pilot and not long after (couple hundred miles maybe) having the timing belt, water pump and aux belts replaced I started hearing this noise (video link) soon after startup with low load. The noise goes away after driving a little. You can hear in the video when I put it in gear what happens with the noise. Also noticing a little hesitation when I accelerate, but that too goes away after a short bit.

I changed the oil again to make sure it wasn't that. Running 5w30 Valveoline Max Life with Tough Guard Fram filter.

http://youtu.be/_dpdf5skg90

[whizmo]

Originally Posted by Underdog

It is not an oil issue.

I agree. Some folks love to make every thread an oil thread.

Sounds like mild piston slap to me. It has a freq of about 12-hz which is once every crank rev - this suggests crank-related rather than valvetrain or cams. If piston slap, this is a sign of accelerated wear, but I've seen engines run with noise like this for 100K miles. I had a Nissan Pathfinder once that made this sort of idle noise since new until I traded it with 60K. It would go away at high RPM or load. I couldn't get Nissan to ever admit any problem.

Could also be an accessory or something, but it sounds a little more "deep down" to me.

- Mark

[belundy]

Actually, the noise occurs 6.3 times per second, or 378 times a minute, or at half crank speed (756 RPM).

[belundy]

The cold start noise doesn't seem to be any louder than warm, so piston slap would not have been my first suspicion. A valve with really loose lash...still?

Does the noise get any louder or deeper under load --like under braked stall?