Loud timing chain rattle. Need help. (Video inside)

[03silversvt]

I have a 99 mountaineer with V6 that my sister gave to me 2 years ago. Its always had this rattle and i saw the threads on here about replacing the front tensioner. truck has about 110k miles on it and i have put about 20k on it with this annoying rattle. Just havent had time to fix it and i was thinking it was the easy fix of just doin the front but im not so sure if the sound is coming from the front or the rear. The other issue at hand here is that it does not have this loud ass rattle all the time. Sometimes also included in the video the sound will NOT be there AT ALL. It will be as quiet as a mercedes even if i rev the engine. How the heck is that possible? You would think that if there is slack in the chain, it would be rattling all the time. Your thoughts please. here is a video.
http://www.youtube.com/watch?v=r0AJluWkt-U

 

[dogfriend]

Sticky tensioner? I don't have a lot of experience with the SOHC (I have OHV) but that is definitely a timing chain rattle. I had a 4 cyl engine once that sounded like that.

 

[cshuman]

Tensioner is going bad if not already bad. Careful, could loose the engine. the v-6 sohc are known for this.

 

[bluestream1]

I would not be reving it too high. Take off oil filler cap on look in with flashlight, you may see the chain jumping around, unless it the primary , ot right chain...

 

[03silversvt]

so most likely its the front of the engine and fixable with the engine in?

 

[cshuman]

so most likely its the front of the engine and fixable with the engine in?

werd

 

[bpopp]

There's 3 chains in the SOHC. One that runs from the crankshaft to the jackshaft (front). One that runs from the jackshaft to the front camshaft (driver side), and one that runs from the jackshaft to the back camshaft (passenger side). Any of them can fail, but for some reason I hear a lot more about the front camshaft one failing (anyone know why?). Both the front chains can be fixed in the truck by pulling the radiator. From what I've been told, you have to pull the engine to do the back one.

I've lost one engine to this. It slipped the front chain after rattling for a little over a year. It did it while I was cranking it and it was not a pleasant sound.

It's worse on startup because the tensioner uses oil pressure to keep the chain tight. One of the things I noticed on mine before it went was that the oil pressure light started staying on longer when I'd crank the car. I later found out that this happens because as the tensioner and cassette fail, they drops little pieces of plastic into the oil pan which block the oil intake.

I'm now on my second engine (junkyard). So far I haven't heard the rattle, but as it gets older, I'm getting more and more paranoid. I'm thinking about pulling it just to be safe.

 

[my98nnj]

That sounds like loud lifters plus an exhaust leak. My slight chain rattle sounds nothing like that and only happens between 2700 - 3000 rpm's. Almost like spark knock and goes away once it all warmed up.

 

[vroomzoomboom]

That sounds like loud lifters.

SOHC's don't have lifters

 

[03silversvt]

yeah, they are not lifters or an exhaust leak. the rattle does not go away as the engine warms up either. it is present 90 percent of the time where ever and when ever. It just so happens, sometimes on rare occasion that when i turn off and restart the car the sound will be netier present or not as loud. It is deffinately the sound of a chain rapping on an aluminum cover.