Whats This Noise?

[smiffy 99]

Bad luck mate, no idea how to proceed now, good job you can do most of the stuff yourself

[xyy81t 0]

in keeping with the title of this thread and as i made this vid for another forum thread which is yet to offer any possible leads i give you noise number 2

 

http://www.youtube.com/watch?v=v_LI-XpUuFg

[smiffy 99]

It's a Whiney something or other my Gtv does that I've noticed, could be a pulley or tensioner on the way out?

[Smaky 73]

First noise is the starter hanging, second is the variator, third is a mix of failing belt pulleys and the forth is big end knock, remove the cam cover and heck the lobes for wear.

 

nice look round a CF2 there aswell.

Edited August 25, 2012 by Smaky

[xyy81t 0]

Thanks smaky, i am only worried about the knocking at the moment. the belts have just been changed including tensioners and idlers so the pulley noise you mention is probably for the aux belt idler or tensioner.

 

cam lobes are not significantly worn although i am pretty sure the knock is coming from the top-end, any way to be sure about bottom end failure without removing the sump?

 

Here a link to the photos i took when changing the belts. Perhaps you could cast your expert eye over them and see if you can spot anything obvious.

http://s470.photobucket.com/albums/rr70/micahwilkinson/145%20QV%20Bob/

[xyy81t 0]

okay heres a bit more information:

 

At idle in 1st gear releasing the clutch gently putting load on the engine makes no change to the knocking, it is barely audible at idle.

 

when disconnecting the variator solenoid the noise is significantly reduced, upon replacing the connector the stutters (as expected) and recovers and the severity of the noise returns.

 

the noise is loudest at around 1500-2000 rpm. (i have not revved it over 3000)

 

just thinking out loud here: is it possible that a failed variator would cause these symptoms? it sounds to me like the timing on the inlet cam is out, could a failed variator cause the timing to be set incorrectly? i.e if it was not returning fully to its natural position and as a result is over-advancing the inlet cam shaft?

 

Here's another video, it sounds really loud and horrible but in reality at idle the engine sounds sweet as a nut.

 

i think the next step is to replace the variator and see if that solves it?

 

http://youtu.be/6GSmQ4MQ0jE

[Smaky 73]

It is possible as there is a spring in the variator and should this snap (which I've never seen) then it's possible that the variator could allow the inlet to rotate out of synch, BUT it would NEVER allow the valves to collide because if that were so then every time we hit 3K rpm then we'd have to replace the vales, with that style on variator solenoid though you can unplug it and check there is resistance between the 2 rivets, then you'll know it's working, then when it's running and connected, rev it up to 3500rpm and check for 12V accross it to prove it's working, but that sound is just too deep to be anything other than big ends or thrust bearings.

 

Also try running the engine with the Aux belt and balance belts off to ensure it's not anything driven by those causing it.

[xyy81t 0]

I agree, the sound is very similar to that of a bottom end knock and thinking about it, if the timing is set with the variator in the advanced position then over advancing would be impossible it would however be possible to over retard if the variator then returned to its natural position. However, I have never heard of a bottom end failing so suddenly and not knocking under load. I guess I'll have to strip the bottom end and see

[K9d 108]

When the bottom end went on my 2.0 it went from knocking to completely knackered in 10 minutes, but the engine sounded like a bag of nails so was unmistakable.

[Alfa156Melb 9]

Yep, sounds exactly the same as my motor when its big end when pear shaped.

[xyy81t 0]

yep Its deffo the bottom end checked the timing again tonight and its spot on and checked the compression too and getting 190psi on first three cylinders and 200 on the fourth with a dry test so no leaky valves there, will start stripping down the bottom of the engine at the weekend, hopefully a new set of shells will suffice although i'm painfully aware that all my testing may have damaged the crank, if so then i'll have to pick up a replacement from the local scrappy, i can't be doing with re-grinding it and finding fatter shells...we'll see