Engine sounds like a diesel

Hello! Long time listener, first time caller. Been chasing down an answer for a couple weeks now- about ready to take it to a shop but figured I’d throw it on here first.

Bought an 04 Tundra about a month ago. I’ve had 4 other Toyotas with the 4.7 and all have had some sort of tick (likely cracked manifold on all). This one sounds a lot different and the only thing I can relate it to is that it sounds like a diesel- doesn’t go away when the engine is warm. Last week it was idling super rough and low and cel came on for ignition coil. Replaced all 8 coils with oem denso and replaced spark plugs. It helped with the low rough idle but the diesel sound didn’t go away.

Any ideas what it could be?

 

Sounds almost like a noisy injector or valve train rattle to me listening on my phone. Definitely seems like it’s more on the passenger side for loudness. I’d be tempted to say it’s cracked manifold on passenger side but have some questions because it’s so rhythmical…

How many miles?

When was the timing belt done last?

Does the noise persist if you remove the serp belt?

When was the PCV valve last replaced?

Have you popped off the valve cover vent tube on the driver side to see if it increases or decreases?

 

Sounds like noisy valve train to me. Any idea on the service history? Last oil change? Oil type? Timing belt? Manifold leak is usually a distinct ticking and can be isolated with an automotive stethoscope.

 

Really sounds like valvetrain/tappet noise to me. When I got my other car, a vintage Fiat, the engine made some really similar noises. The tappets were very far out of adjustment. Also when listening with headphones I feel like I can make out the injector clicking- which is normal.

Valvetrain noise is odd though, because it's not common or normal. These engines are incredibly stout and valvetrain noises are very uncommon. I believe the owners manual states that a valve check or adjustment should be done at 120k miles, but I've never heard of anyone actually doing that to a 4.7. Even googling it brings up little results about actually changing the shims on the tappets.

How many miles are on the truck? Do you know oil change history?

 

Sounds like valvetrain to me. But manifold leaks can make all sorts of different wierd noises because of the heat shields and how the leak resonates against it.
You could get someone to hold a rag over the end of the exhaust pipe and see if it changes.

 

To that point though, I can't recall who the member was whose truck sounded similar recently, he changed the timing belt and pulleys, and it purred like a kitten again. Not even the ticking many people associate with injector noise. He posted before/after videos.

 

Might be injectors, but it seems too loud for that. Something like this might help you localize the noise:

 

I have one that is starting to sound that way,. Fresh oil change did not help, 257k, belt due in 20k