Timing chain? Unsure issue

[nzv8farmer]

So I've been doing the searches and keep reading about the same issues and struggling to find my answer (it's probably there somewhere but with 1300 google results I wave the white flag)

Our second commodore, a 2004 VZ acclaim wagon started an odd timing chain rattle a couple days ago, never done it before. It started rattling at cold start and continued, increased in speed related to engine revs, stopped engine and was still there, there is no engine codes, and there is nothing out of place. After a while, the amount of time varies, it goes away, and it doesn't happen every start, but it does happen when it's warm sometimes as well and these are all the parts that confuse me.

I would have thought if it was a stretched chain it would happen every time it started and would either go away after a short while or stay continuously, and I've read of a few people that have tensioners break and that has caused massive issues including car not starting but we have a running car with no loss in power. One thought I had was maybe a blocked or gunked up tensionor but unsure. Maybe oil pump or oil pump chain? Any thoughts or suggestions?

And with that, if I'm going to strip front of engine down, should I just change the chains, tensioners anyway? What about oil pump?

 

[markovr]

you will be able to see whats ahead of you when you take the plenum off and then the valve covers....as you have probably seen from my other thread pictures it aint pretty and my chains were not stretched when i took mine apart ...just blocked oil gallery that feeds one tensioner and while you have the front off you might as well take the sump off
I did not have any codes when mine started rattling but the oil warning came up at a later stage

 

[Calaber]

Here's a thought. If the engine has blocked oil galleries, would it hurt to run it with an oil change of diesel oil which is generally a high detergent oil? Perhaps with fresh oil and filter, the system can be flushed out and then changed again after say 100 to 200 km.

Others here may ****-can this idea but it's worth a try isn't it?

 

[markovr]

i actually ran a litre of diesel fuel in the oil for about 15 mins at idle speed and drained it and I did it a few times....didnt hurt the engine and it didnt seem to create anything extra noise wise but it didnt fix anything either and in the end pulled it apart
As you can see there are plenty of oil galleries in the front of the engine oil pump removed

Although the actual holes are quite big