4.0L sounds like a diesel

[stonerhino]

So my 4.0 2004 v6 engine has this very rare sound it makes. This is quite rare, but when you do hear it, YOU HEAR IT. It is unpredictable and happens on engine startup.

It's coming from the drivers bank. Goes away when you restart engine. Doesn't happen when driving or coming to a stop.



Any ideas?

 

[BobRob]

That almost sounds like an exhaust leak, but you lose something with sound through these tinny speakers I have.

Could be a weak timing chain tensioner spring, which would explain why it goes away once oil pressure takes over. The drivers side one is easy to change, lots of threads on it.

 

[stonerhino]

That almost sounds like an exhaust leak, but you lose something with sound through these tinny speakers I have.

Could be a weak timing chain tensioner spring, which would explain why it goes away once oil pressure takes over. The drivers side one is easy to change, lots of threads on it.

The sound will NOT go away until engine is restarted. I let it run for 5 mins and it was at operating temperature. Also it is persistent after bumping throttle a few times.

 

[BobRob]

The sound will NOT go away until engine is restarted. I let it run for 5 mins and it was at operating temperature. Also it is persistent after bumping throttle a few times.

When you say drivers bank, is it coming from the front, rear, top? I'm trying narrow down the source since there are lots of things that could cause what you're hearing. Not sure why something would go away when restarting unless something is hanging up for some reason.

 

[stonerhino]

When you say drivers bank, is it coming from the front, rear, top? I'm trying narrow down the source since there are lots of things that could cause what you're hearing. Not sure why something would go away when restarting unless something is hanging up for some reason.

The vid was started in the driver's side in the wheel well. Sounds primarily like one or two cylinders doing it. The engine has 180k on it. Bought it with 170k.

 

[BobRob]

The vid was started in the driver's side in the wheel well. Sounds primarily like one or two cylinders doing it. The engine has 180k on it. Bought it with 170k.

I'm sure others will chime in, but I'll take another listen on better speakers when I get home.

 

[Tech By Trade]

Change your tensioners quick. If you leave them too long they will cause premature chain guide failure if they haven't already.

 

[stonerhino]

Change your tensioners quick. If you leave them too long they will cause premature chain guide failure if they haven't already.

They were replaced a week before I purchased the vehicle. I have the service log with the tech's name as it was a company vehicle.

 

[stonerhino]

So i took it to the stealership. They heard it. Their response was "you need tensioners". I showed him the logbook, his response was "i know that tech! And he replaced them?". It was followed by, "man you need to get those fixed quick".

Question, since the vehicle was sold as-is, could i make the guys i bought it from responsible?

 

[2000StreetRod]

tensioners not always the solution

Replacing the tensioners is the first step in resolving timing chain related rattle because of the relative low cost of parts and labor. Replacing the tensioners will not fix broken cassette guides. In most states "as is" means exactly that. No warranty is provided no matter what is stated by the seller. It's basically equivalent to "let the buyer beware". The following threads may be useful:
Don't buy 3rd Gen with 4.0L
Timing chain rattle resolution process - SOHC V6
SOHC V6 Timing Chain Inspection & Repair

 

[Tech By Trade]

Hope you can swing a wrench or have deep pockets. Your exploder probably doubled in cost.

 

[stonerhino]

Hah, yeah. It did. But the firmware update fixed a lot of other problems at least. Doesnt take 15 seconds to go into gear.

I am not afraid of slinging wrenches. Did it for many years on my 89 5.0.

My problems are the lack of equipment to pull the engine, and a safe facility. My medication makes it difficult to work in the sunlight.

Right now, its not making any kind of rattle. Usually it take about 20 mins of driving before things sound normal.