SOHC noise only when warm (video)

[Hitchhikingmike]

My SOHC makes noise from the heads only when the engine is warm. The sound cannot be heard in the cabin and is not unusually loud and does not grab your attention when the hood is shut. The engine has made this sound as long as I can remember, it might have gotten louder though.

Below is a video of a cold start. In the beginning you can hear that the engine is quiet. Snap to 3:07, when the engine is warm and you can hear sound from the heads. It sounds like there are pebbles and small rocks just being thrown around.



Engine has never had a mechanical problem before, has 88k miles and Amsoil has been used for the last 50k miles. Engine still gets good fuel mileage and has plenty of power.

I am aware of the chain rattles these engines tend to exhibit and wonder if my timing components might be loosening up. If they are, and this sound is a precursor of worse things to come, this summer is the time for me to pull the engine and refreshen the timing system before the Fall semester of school starts up.

General thoughts and comments welcomed.

Thanks.

 

[Hitchhikingmike]

Here is another video of the sound of the engine already warm. You can hear the sound a little bit better here:

 

[1AJeremyD]

sounds like once the oil gets up to temp the normal timing chain noise starts. Its the beginning of the end for that one. I would definitely take the time and change it out sometime soon. I think it will only get worse as the summer progresses and temps rise so the oil will be thinner quicker

 

[2000StreetRod]

remove serpentine belt

I suggest that you remove the serpentine belt and run the engine (only for 1 minute). If you still hear the noise then you know it's from the engine. If no noise then it's from the accessories (belt tensioner, idler, alternator, PS pump, A/C compressor or water pump).

To me it doesn't sound like the typical left or right timing chain slap. If it's timing chain related I would guess the primary (crankshaft to jackshaft) chain tensioner or if you have 4WD the balance shaft chain tensioner.

Timing chain rattle resolution process - SOHC V6

SOHC V6 Timing Chain Inspection & Repair

 

[Hitchhikingmike]

I suggest that you remove the serpentine belt and run the engine (only for 1 minute). If you still hear the noise then you know it's from the engine. If no noise then it's from the accessories (belt tensioner, idler, alternator, PS pump, A/C compressor or water pump).

To me it doesn't sound like the typical left or right timing chain slap. If it's timing chain related I would guess the primary (crankshaft to jackshaft) chain tensioner or if you have 4WD the balance shaft chain tensioner.

Timing chain rattle resolution process - SOHC V6

SOHC V6 Timing Chain Inspection & Repair

Thanks. I just replaced all my idler pulleys. However the engine does not make this sound when it is cold, so it must not be belt related. I did run the engine without the belt on and it was quiet. Although I did only run the engine without the belt when the engine was cold.

Also, it is not 4x4 so I do not have the balance shaft.

 

[Hitchhikingmike]

Also, I prodded around with a mechanic's stethoscope and the noise is most audible from the intake manifold. I put the stethoscope on the valve covers and the heads where the chains were and the noise was most audible form the intake manifold.

Thanks, Mike.

 

[Hitchhikingmike]

Nevertheless, the fact that the noise only occurs when the engine is warm must mean that the tolerances in the engine must be too large when the metals expand when warm. I might just take it to a mechanic to get an opinion.

Any other thoughts? Should I pull the engine this summer and overhaul the timing components before it gets worse?

 

[2000StreetRod]

water pump?

Your 2002 should have all of the timing chain improvements. Since you have been running synthetic oil for the last 50K of your total 88K miles I would be surprised if a guide or tensioner has failed. I suggest that you check the water pump bearing for excessive clearance. Look under the vehicle for coolant leaks on the bottom of the water pump. Grab a fan blade and check for play in the water pump bearing.

 

[Hitchhikingmike]

I went out to the truck tonight. I ran the engine until it got warm (180F). I then shut the engine off, took off the belt and started the engine back up only to hear the same tapping/rattling sound. I also prodded around for a good while with my mechanic's stethoscope and could not conclude anything substantial.

On a good note I wiggled the shaft of my water pump since you suggested it, and found unusual play. Thanks to your suggestion I've at least found out my water pump is on its way out and I'll be replacing it by the end of the week now.

I am still at a loss for the source of the noise. I do know for a matter of fact the sound is louder on the driver's side than the passenger side to the ear just walking around.

Thanks for the suggestions thus far.

 

[Hitchhikingmike]

I really owe you a beer Dale! If you remember in a previous thread last winter you found my oil leak and now you just had me discover that my water pump is on its way out!
I'm about to head out the door now to go pick up a new pump.

 

[Hitchhikingmike]

My Explorer was assembled in 2002. But I'm thinking I may have gotten a pre-2002 SOHC that did not get the updates.

I've also been listening to other videos on you tube and my noise sounds awfully similar to all the other chain related problems, just not as loud.

 

[xplorerguru]

mine sounds the same way mike! its an 05 tho, not as loud as yours but it has that rattle going on... sounds almost like a mini diesel. It better not be the timing chain...

 

[Hitchhikingmike]

After listening to my engine for a good while more, I have concluded that the sound is due my fuel injectors. I believe that I just have loud fuel injectors.

Because my engine is whisper quiet (almost) on startup, I have to rule out anything related to the timing chains. If they or the tensioners were bad, I believe they would have to clatter on startup.

I also replaced my water pump.

 

[2000StreetRod]

injector noise

Fuel injector noise is extremely regular with regard to engine speed since each injector only fires every other revolution of the crankshaft. If you listen to each one with a mechanic's stethoscope or length of hose placed close to the injector you'll become familiar with the noise and its rhythm. You can unplug one of the injectors to further isolate between injector noise and timing chain rattle.

As I stated in a previous post your sound to me does not sound like the typical cassette timing chain rattle. Since you don't have a balance shaft, if you do have timing chain problems it is probably the primary (crankshaft to jackshaft) chain tensioner. That noise is less severe at idle and engine start. It is loudest at midrange engine speeds. It is unlikely the primary chain will slip and cause engine damage due to a failed tensioner. When I replaced my timing chain components I could not manually get the primary chain to slip even with the tensioner and guide removed from the engine.

 

[Hitchhikingmike]

Fortunately the sound does not increase with idle speed. I am confident the sound are the fuel injectors.

Thanks Dale, I value your opinion.

 

[waskly]

what oil weight are you using?

 

[Hitchhikingmike]

5W-30, the only weight oil the engine has ever seen.

 

[waskly]

in the first video at 2 min 50 seconds, thats an injector tic

 

[Hitchhikingmike]

in the first video at 2 min 50 seconds, thats an injector tic

I noticed that the sound originates mostly from the intake manifold and originally found this odd. The fuel injectors now make more sense. Since hey are mounted above the valve in the heads, their sound must be resonating up into the manifold.

 

[cross6]

Sounds like fuel injectors to me. My truck has always sounded like that near the valley area.