Raspy noise from V6 when cold

[defecat0r]

Hey guys, I've had a problem with the old girl for a few months now. It's had a pretty bad raspy sound coming from the engine when i start it in the mornings, it was particularly bad through cold mornings in winter. Recently it's been getting worse and is happening any time the car's been off for more than an hour or two.

It's a V6 with 474k on the clock. I've taken the belt off and the problem remains. The sound seems to be coming from inside the engine, it's very loud at the throttle body with the airbox and all that taken off. A wild stab in the dark I'm thinking maybe a broken timing chain tensioner?

I've uploaded a video here:
https://youtu.be/JNQBHEARW6s

first ~20 seconds the car has just been turned on from cold, last ~20 seconds it's been on for a few minutes and is doing it's "hunting idle" thing that may or may not be related. I've changed IAC, TPS, MAP sensors trying to fix that one but i'm not too concerned about it.

Hopefully someone will recognize this sound, cheers!

 

[vy1tonnerbloke]

With 474,000 km one would expect things to be getting pretty loose inside the old girl. If you fix one thing it won't be long before something else breaks, surely. Time for an upgrade?

 

[hi_ryder]

he beat me to it^^

sounds like chaos. it could be a timing chain problem.... could be other things too. my advice would be to swap it with something with less k's on the clock. youll fix this problem then other stuff will start popping up. then it will be like playing whack a mole. a buick with almost half a million on it is a good effort.

 

[Wozza]

That doesnt sound to bad for a 474K engine, Its a bit hard to hear with the induction noise...but sounds like you have a bit of piston slap or gudgeon pin rattle...cam chain noise will go quit when reved and then rattle its tits off as throttle closed and the revs come down to idle then will grumble at idle...maybe a bit of lifter noise as well....I say dont worry about it, go for 1/2 mill and save ya $$ for a replacement motor or just buy a donner car

 

[defecat0r]

Haha people have been giving me the "ditch it" advice for years now, but I'm stubborn and love this car so i want to keep it running as long as i can.

Wozza, those symptoms you describe are exactly what's happening: noise quite when revved then noisy as throttle is closed. It grumbles loudly at idle while it's cold, but when it's warmed up and with the air intake stuff on it's not audible.

So at this stage i'm planning to replace the chain tensioner, which while labor intensive seems pretty cheap - only need to buy a chain-tensioner and the timing cover gasket. I was also planning on pulling the gear off the balance shaft while in there too (and leaving it in place) as apparently that's another source of problems.
A replacement chain and sprocket kit seems to be around $200-300, would it be silly to not replace them while in there or considering the car might be on it's last legs would it be sensible to leave them? Should i be doing anything with the oil pump - I'm reading people suggesting replacing the "oil pressure relief valve spring", but i guess that can be done at another time and doesn't need to be done with the timing cover off?

Thanks for the advice

 

[Jxfwsf]

There's another noise?
Can make out the extractors working and the induction noise.....
Put the intake pipe back on and muffle it, video/audio compression when uploading things distorts it even more.

 

[HarryHoudini]

If your doing the tensioner then replace the chain as well,it will be worn/stretched,also(the list is endless on a old motor) you may as well do the Harmonic Balancer & CAS while your there,if you change motors you can always take them off and fit to a new motor.

 

[someguy360]

Haha people have been giving me the "ditch it" advice for years now, but I'm stubborn and love this car so i want to keep it running as long as i can.

Wozza, those symptoms you describe are exactly what's happening: noise quite when revved then noisy as throttle is closed. It grumbles loudly at idle while it's cold, but when it's warmed up and with the air intake stuff on it's not audible.

So at this stage i'm planning to replace the chain tensioner, which while labor intensive seems pretty cheap - only need to buy a chain-tensioner and the timing cover gasket. I was also planning on pulling the gear off the balance shaft while in there too (and leaving it in place) as apparently that's another source of problems.
A replacement chain and sprocket kit seems to be around $200-300, would it be silly to not replace them while in there or considering the car might be on it's last legs would it be sensible to leave them? Should i be doing anything with the oil pump - I'm reading people suggesting replacing the "oil pressure relief valve spring", but i guess that can be done at another time and doesn't need to be done with the timing cover off?

Thanks for the advice

If you really love the car, swap the engine.

Only takes a few hours to swap a V6 and will cost you around the same $2-300 mark that the timing chain kit will cost you, the last ecotec motor I bought was 240,000km for around $250

It's absolutely pointless paying for parts for a half million km engine.

 

[VK SL 3800]

In the Video it sounds just like the LPG mixer is making some made induction noise.

 

[vy1tonnerbloke]

In the Video it sounds just like the LPG mixer is making some made induction noise.

Yeah it actually really does....maybe that's all it is?