I have a very sporadic rattle on the timing chain side of my engine bay of my 07 IRL. It happens at start up and increases with RPM. It does not happen often. Maybe once every 300 start ups. I noticed it last when I was due for an oil change. Roughly 7500 miles ago. I changed the oil, and I went ahead and changed the timing chain tensioner, and it happened at the initial start up after change, and to my knowledge went away on the next start up.

It reappeared today, which is almost exactly 7500 miles since last oil change. I started the car, had my girlfriend rev the engine, then shut the engine off. Then I restarted the engine and it was gone. Can this sound be caused by aging oil? Possible thickening, causing less lubrication to the timing chain, causing a rattle?

BTW I use Mobil 1 5W-30 Extended Performance Oil and Filter.

 

Change that sludge. 7500 miles is too much.

 

one thing ive learned with ecotecs is the oil may last 7500 miles or more, but the filters sure dont. i typically go 7500 KM (roughly 4500 miles) between oil changes, any longer and when i pull the filter out its collapsed. this is showing that the filter is restricted.

i dont recommend long life oil, its not worth it. if your going to run extended life oil you need to change the filter every 5000 miles.

 

1. Mobil 1 extended performance his a great oil that will last 7500 miles no problem
2. Use good filters
3. Change the filter every 3k or so if you are going long life. It's top load and can be changed easily between oil changes

 

get away from 5w/30 run 15/40 and change the oil every 3500 miles I would run rotella in it

 

Reasoning for running that weight?

I do notice that Mobil gets super thin after a couple thousand miles. I run whatever name brand 5/30 synthetic that's on sale when I need it and change it at around 40% oil life.

 

There is no reason to run anything but 0w30 or 5w30.

 

Yeah...glad we got the oil tutorial out the way. 😉 Regardless I have ran every car with synthetic at 7500 miles. I've never had any issues. In regards to filters I could see possibly changing the filter in between oil changes, but I've never experienced a crushed filter since changing to Mobil filters. This is my second ecotec, first was a lnf, for almost 100k and the lsj has 87k on it with 25k mine and I've always done 7500 mile oil changes. But anyways...

Anybody else experience the random noise? It literally sounds like the timing chain, but I figured when I changed the tensioner to the new design 7500 miles ago it would have stopped. I'm not discrediting it being the oil at all, but I wonder of its a worn guide too. I don't have any misfires, and I've yet to find shavings in the oil, but who knows. I would figure if it was the timing chain, it would slap consistently.

Again, it only happens every 300 cranks or so. It hasn't happened the last 4 times I drove it. I also question if it's my resonator causing an exhaust vibration that is traveling up towards the engine. I know the resonator is about shot.

I guess I will change oil tomorrow and get the muffler shop to cut out the resonator and weld a straight pipe in. Maybe it won't come back after I do that. Who knows 🤔

Thanks for all the replies.

 

If it's that infrequent then I wouldn't be too worried. Could also be from sitting or slightly low oil.

I have had several cars that hate to be cold started like that.

I will say that most people that mess with the timing components usually change all components at once to make the setup last a long time

 

Rattle found - Tensioner pulley assembly - 12583180. It's slightly loose, but I cant seem to tighten the damn thing any further. I suppose I can essentially add some washers to the front of the bolts if I can get the POS off.

 

The pivot bushing in it is probably worn. Replace the assembly. I think I have a new one laying around somewhere if you can't find a good deal on it.

 

If you can track it down, shoot me a pm.