depami

Can anyone identify this noise?
Listening with a mechanics stethoscope, it is loud at driver side T-belt cover. Can’t really hear it anywhere else.
Timing belt, water pump, tension wheel were put on new in 2015 but car hasn’t been run until now.
Please help me find the source of this noise.
Thanks.





Cheers,

ZEUS+

I had a similar noise. It was the left/drivers side cam hub. https://rennlist.com/forums/928-foru...ine-knock.html

davek9

What does the T Belt tracking look like through the Vent holes?
Should be a a few mm from the front edge on both cams and not much wobble if any.

depami

I'll post video through vent holes tonight.
But, in the mean time, a bit more information.
There is a delay after start up until the sound begins.
The delay is longer on cold start than warm start.
As I ponder this, oil pressure comes to mind.
I'm not familiar with the cam chain tensioner but I'm guessing oil pressure increases tension over static spring tension.
Could this cause the shoe to "wobble" and produce such a sound?

Cheers,

depami

OK, it seems cold start takes a couple minutes for sound to be heard (my hearing isn't the best so maybe sooner) and worsens as engine warms up. Warm starts only take a few seconds for me to hear it. I can hear it on both sides but much louder on driver side. It certainly seems to be related to exhaust cams. But is it coming from belt into cams or from cam into belt? Can't hear it on cam cover "large areas" but very prominent where arrows point.
Where do I go next?
Pull belt and check belt and all "turning parts"?
Pull cam sprockets and check hubs?
Pull cam cover and check chain and tensioner?
Etc.?
Thanks for any and all advise.







Cheers,

depami

Oops!
Forgot vent hole images.





Cheers,

ZEUS+

If it is the cam hub(s), you don't want to keep running it. You said "It certainly seems to be related to exhaust cams." The gear and hub are on the exhaust cam. It was actually easy to diagnose, just a lot of worrying. Remove the dist. cap and see if the rotor is loose. Remove the rotor and see if the cam bolt is loose. Hopefully it's something else. Odd for both hubs to fail, but anything is possible. Mine was much louder, unless it's just the video.

Mrmerlin

it looks like someone has been prying on the cam pulley and bent the snout of the cam.
If the cam pulley wont slide off then use a puller and heat the hub of the pulley

depami

Thanks guys,

I swapped rotors and caps side to side and nothing was loose.
I'll lock the crank at 45, pull the belt and sprockets, inspect the hubs, and check cam runout with dial indicator.
Think it's worth pulling the cam cover(s) to get a better look at tensioner(s)?

Cheers,

Mrmerlin

Note it could also be possible the spider is bent instead of the cam it might be worth replacing the spider then run it to see if the cam pulley runs true

depami

Not sure this means anything but here they are:




Cheers,

depami

Should the belt be riding this far forward on the crank sprocket?
It's actually wearing into the front flange.
There seems to be spare clearance on the back side but there's no direct adjustment for this.
Is there something with the tensioner that could cause this? Could it have bad bushings or could shims be used to direct the belt for and aft?
You can see where it looks like the belt is wearing in some spots but not others.
I suppose this could be the source of the noise but even if not, I feel that it needs to be addressed.
I have a new belt on the way but am reluctant to put it on until I get to the bottom of this forward riding wear.
The old belt hasn't been removed yet but will be, along with the cam sprockets to inspect them and the spider hubs.
Then I suppose I'll be buying a PK32Vr. That or remove the cam covers again to time the cams.
What say all?
Thanks.













Cheers,

Mrmerlin

The belt will track on the front edge of the crank drive gear make sure your curved thrust washer is flat against the gear they get bent from prying on them replace the pivot bolt and bushings on the tensioner arm
verify you have the snap ring installed on the tensioner roller bearing shaft can’t overnight the bolt that holds it in the arm the belt should track close to the front edge of the roller and could have a slight overlap of the front edge
make sure the pivot bolt is not bent if you don’t replace it always replace the bushings I put dc111 on them so it won’t rust inside the arm bore

dimmer

I had a similar issue many years ago.
The new T-belt turned out to be bad.
If you take everything apart and find no issues with the parts or assembly, I would suggest replacing the T-belt ... they aren't very expensive.

depami

Thanks, I've got one on the way, should be here Monday.
Don't have the old one off yet but that should happen yet today or tomorrow.
Then I'll check all the rotating components the best I can and if nothing obvious, try the new belt.
The sound only becomes noticeable, at least to my failing ears, after warm up.
The only thing I can think of is the tensioner relaxing and allowing the belt to loosen slightly.
Don't think the tensioner would 'cause' the noise, but I suppose it could allow it to 'amplify'.
The only components that could be involved are the water pump, oil pump, tensioner wheel, and of course, belt.

Cheers,