Timing chain tensioner gone bad?

[Hatchet]

Ive listened to the video a few times now. The only time I've heard a noise like that is from the fan hitting the shroud. It sounds like plastic on plastic, but it is tough to tell through a video. It is obviously linked to your RPM, so that doesn't really narrow it down as that is 90% of the engine. I forget if you said you have removed the serpentine belt and let it run that way and if noise is still there. That can eliminate the accessories.

IMO if the timing chain was that loose that its knocking around that loudly, the timing on the cams should be off and getting some kind of check engine codes. At this point, what I would do is take off the valve cover and check out the top end and top of timing chain. If that ain't it, its a few hours of time a 10 dollar gasket to put back on. Unless there is someway to get a borescope to the timing chain from the oil fill, but I don't think there is.

With the valve cover off you should see this at the beginning of the video. (video is from a destroyed rocker on the I6)

[video=youtube;TmhXKqgygcw]https://www.youtube.com/watch?v=TmhXKqgygcw[/video]

 

[Revans381996]

Now that I think about it, you're right I should pull the valve cover off just to see if it will give me any clues on what's going on. I think I'm gonna plan on doing that within the next couple of weeks. How hard is the valve cover gasket on these engines? I've done a few valve cover gaskets but only on 4 cylinder engines that were pretty easy.

 

[IllogicTC]

Now that I think about it, you're right I should pull the valve cover off just to see if it will give me any clues on what's going on. I think I'm gonna plan on doing that within the next couple of weeks. How hard is the valve cover gasket on these engines? I've done a few valve cover gaskets but only on 4 cylinder engines that were pretty easy.

The bolts actually securing the cover are "loose." As in, when tightened to spec, they're like 89 inch-pounds I think it was, but don't take my word on that. I know it's some really light torque figure. And on that note, make sure you have an inch-pound capable torque wrench available to get them back to spec when you're putting it all back together.

One of the hardest parts probably will be working around the A/C lines that just have to run over the thing. Taking your time and thinking out your movements could greatly help, unless you have the expertise and equipment to safely move or remove the lines.

 

[Texan]

Here is a link to pictures of the TB valve cover/cam phaser work in the above link.

technologic80's Library | Photobucket

I might have figured it out.

http://gmtnation.com/f25/woke-up-today-p1345-1979/

 

[Hatchet]

Now that I think about it, you're right I should pull the valve cover off just to see if it will give me any clues on what's going on. I think I'm gonna plan on doing that within the next couple of weeks. How hard is the valve cover gasket on these engines? I've done a few valve cover gaskets but only on 4 cylinder engines that were pretty easy.

Simple. Then again, last time I did it, the engine was out of the vehicle. But it was a few mins, it's all the prep work that will take the longest. intake, throttle body, coil packs, wiring you gotta move out of the way. Just a note for you. There is 1 bolt i believe at the very back of the engine on the valve cover that people miss and end of breaking the valve cover.

 

[AbsoluteZero]

I don't have anything to add to identify the noise source.... but wonder if an oil analysis would give an indication if it's internal. In which case the quest to solve and fix would be hastened!